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  • 251.
    Augustsson, Nathalie
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Löfström, Helena
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Evaluation of the virtual training softwares SeQualia and Vizendo2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The automotive industry is constantly developing and manufacturing industry is facing modernisation and need for increased efficiency which implies that the automotive industry is facing changes for assembly training. To minimise quality errors and save time computerbased training virtual training can be used to practice on product knowledge, variants and sequences. Currently in traditional training in automotive industries, the operators practice on psychical products. The purpose of this bachelor thesis is to obtain knowledge of the effects of virtual training with cycle times longer than five minutes by evaluate the virtual training methods at Scania in Södertälje, Sweden. To achieve the purpose of the thesis the objective is to create a basis of the advantages and disadvantages. Scania is part of the Volkswagen Group and is a world leading supplier in the automotive industry which develops custom made and high-quality products with short lead times. Scania’s core products are heavy trucks, buses and engines for marine and industrial applications. Scania has 46 000 employees in 100 countries. Today Scania use standardised work and Job Instructions Training tools for learning the assembling processes which could be time consuming, ineffective and resource-intensive. Therefore, Scania’s vision with virtual training is to shorten the learning time on-line by implementing virtual training to practice off-line. The main objectives are to reduce the time for training simultaneously as the product quality increases. To obtain reliable information to reach the purpose a qualitative approach has been used in the study. To obtain primary data the methods have been semi-structured interviews, observation and questionnaires that have been performed and literature studies have been used to collect secondary data to obtain a broad knowledge of the subject. Through this the bachelor thesis resulted in recommendations that will contribute to Scania’s decision of future work with virtual training. The recommendations have been based on the previous accomplished studies, results and obtained comments which together were connected in the discussion and by the recommendations the authors believe that Scania can use virtual training with success.   

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  • 252.
    Augustsson, Per
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Mansori, Farsad
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Skapande av dynamiskt modellnät för analys av lasters beteenden vid nätstörningar2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor’s thesis is carried out on behalf of Vattenfall Eldistribution AB in Trollhättan. This work aims to make modelling of power grids for simulations, of load behaviour during perturbations, in PSS/E more effective. Modelling will be made more effective by means of programming, using the programming language Python, and also by allowing certain assumptions to be made about the grid. The idea for this work arose from a certain case, during which Vattenfall was tasked with investigating why voltage levels near an industry would not recover after a short circuit, on the transmission line feeding the industry, was cleared. Investigations demanded simulations of the disturbance to be carried out in PSS/E, to describe what had happened. To enable simulation and to make it representative, the grid and its components must be adequately modelled. Svenska kraftnät has the data nessecary for such modelling, but it is inaccessible due to confidentiality. Due to the data being confidential extensive work with modelling was nessecary. Early simulations were based on the idea that some parts of the grid can be modelled using only simplified models, and with typical, or default, values. This thesis uses that hypothesis in the programming code. The low voltage after these perturbations were caused by motors, more specifically induction motors, drawing high currents from the grid during reacceleration when the voltage starts to recover after the perturbation. This high, and mostly reactive, current causes significant voltage drops across the lines and transformers, in turn causing other motors to draw more current and further lowering voltage. The programming code, called a script, developed during this work allows the user to quickly create dynamic model data to use when conducting simulations of the dynamic behaviour of this type of loads. Modelling of the generators is done quickly thanks to the assumption that generators are located far enough away that they are barely affected by the studied disturbance. They are, for this reason, modelled using typical values. Through a graphical interface, the user then select which loads to model. For each load model, the distribution across different types of loads is specified by the user. Finally, protection relays are modelled to enable current monitoring. The script has been tested by comparisons to a reference network model created by Vattenfall. The comparisons show minor deviation between the script and the reference. This could be because the script uses default values and models less components than the reference.

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  • 253.
    Augustsson, Svante
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Human and Robot Interaction basedon safety zones in a shared work environment2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The work explores the possibility to increase the automation along a production line by introducing robots without reducing the safety of the operator. The introduction of a robot to a workstation often demands a redesign of the workstation and traditionally the introduction of physical safety solutions that can limit the access to the work area and object on the production line. This work aims to find a general solution that can be used not only in the construction industry, but also in other types of industries to allow for an increased Human and Robot Interaction (HRI) without physical safety solution. A concept solution of a dynamic and flexible robot cell is presented to allow for HRI based on safety zones in a shared work environment. The concepts are based on one robot and the usage of a 3D camera system allowing for the design of virtual safety zones, used to control the HRI. When an operator approaches the robots work area and triggers a safety zone the robot stops its work and moves away from the operator. Based on the safety requirements and triggered zones the robot will continue to work in a new area or wait until the operator leaves the work area and then continue with the interrupted work task. This will allow the operator and the robot to work together, where the operator location controls the robots workspace. Testing and validation of the presented concept showed that the wanted functionality could be obtained. It also showed limitations to the equipment and the system used during tests and raised additional aspects of the safety for HRI. Of the detected limitations the most crucial when looking at up-time for the production line, is the camera system need of a relatively dust free environment, good and constant lighting. For the safety of the system the limitation lies in the size and placing of the safety zones in combination with the disturbance from  surrounding equipment. The presented concept has proven to work, and can be applied not only for the construction industry but for all industries with manufacturing alongside production lines with large components.

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  • 254.
    Augustsson, Svante
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Gustavsson Christiernin, Linn
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation Systems.
    Human and robot interaction based on safety zones in a shared work environment2014In: HRI '14: Proceedings of the 2014 ACM/IEEE international conference on Human-robot interaction, New York: Association for Computing Machinery (ACM), 2014, p. 118-119Conference paper (Refereed)
    Abstract [en]

    In this paper, early work on how to implement flexible safety zones is presented. In the case study an industrial robot cell emulates the environment at a wall construction site, with a robot performing nailing routines. Tests are performed with humans entering the safety zones of a SafetyEye system. The zone violation is detected, and new warning zones initiated. The robot retracts but continues its work tasks with reduced speed and within a safe distance of the human operator. Interaction is achieved through simultaneous work on the same work piece and the warning zones can be initiated and adjusted in a flexible way.

  • 255.
    Augustsson, Svante
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Olsson, Jonas
    University West, Department of Engineering Science, Division of Manufacturing Processes. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Gustavsson Christiernin, Linn
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    How to Transfer Information Between Collaborating Human Operators and Industrial Robots in an Assembly2014In: Proceedings the NordiCHI 2014: The 8th Nordic Conference on Human-Computer Interaction: Fun, Fast, Foundational, ACM Publications, 2014, p. 286-294Conference paper (Refereed)
    Abstract [en]

    Flexible human-robot industrial coproduction will be important in many small and middle-sized companies in the future. One of the major challenges in a flexible robot cell is how to transfer information between the human and the robot with help of existing and safety approved equipment. In this paper a case study will be presented where the first half focus on data transfer to the robot communicating the human's position and movements forcing the robot to respond to the triggers. The second half focuses on how to visualize information about the settings and assembly order to the human. The outcome was successful and flexible, efficient coproduction could be achieved but also a number of new challenges were found.

  • 256. Aulenbach, Donald B.
    et al.
    Clesceri, Nicholas L.
    Meyer, Michael A.
    Vasundevan, Chittibabu
    Beckwith, Eileen
    Joshi, Shrikant
    Removal of heavy metals in potw using alum or sodium aluminate for phosphorus removal1984In: Proceedings of Mid-Atlantic Industrial Waste Conference, 1984, p. 318-330Conference paper (Refereed)
    Abstract [en]

    The addition of alum or sodium aluminate at dosages which effectively remove phosphorus is beneficial in removing copper, chromium, and lead when present in wastewaters. Chromium removal is enhanced by sodium aluminate addition, but alum does not affect chromium removal. Both types of aluminum salts appear to increase the removal of lead, but the large variance in the data does not allow this to be confirmed by the t-tests. Of the remaining metals analyzed, no difference in removal was observed with and without aluminum salt addition for cadmium or antimony, nor was there any difference in TOC removal. Mercury was effectively removed to below the detection limit by primary sedimentation, so no further removal was achieved during secondary treatment when the alum/aluminate was added. Other metals were not present in amounts above detection limits.

  • 257. Aulenbach, Donald B.
    et al.
    Meyer, Michael A.
    Beckwith, Eileen
    Joshi, Shrikant
    Vasudevan, Chittibabu
    Clesceri, Nicholas L.
    Removal of Heavy Metals in Publicly Owned Treatment Works1987In: Environmental Progress, Vol. 6, no 2, p. 91-98Article in journal (Refereed)
    Abstract [en]

    Studies were conducted at three activated sludge treatment plants during normal operation. The heavy metals were measured in the influent to each plant, the primary sedimentation effluent where applicable, the discharge after activated sludge treatment and secondary sedimentation, and in one case after a final polishing filter. Both the soluble and the total portions were measured. Beryllium, nickel, and thallium were not found in detectable levels in any of the plant influents. Mercury was found in only trace amounts. The removals of the other metals varied considerably. No consistent conclusions can be made from the data; each metal, soluble or total fraction, and unit treatment operation must be interpreted individually. The only metal in the plant effluents consistently above the recommended limit was arsenic, and this barely above the limit, and the lead content from Fitchburg, despite 83% removal.

  • 258. Aulenbach, Donald B.
    et al.
    Meyer, Michael A.
    Vaseduvan, Chittibabu
    Beckwith, Eileen
    Greaves, Kathryn
    Joshi, Shrikant
    Cleseri, Nicholas L.
    Removal of several heavy metals in potw using aluminum salts for phosphorus removal1983In: Proceedings of the Industrial Wastes Symposia, 56th Annual WPCF Conference.; Atlanta, Ga, USA; ; Code 3809, 1983Conference paper (Refereed)
  • 259.
    Aw, Cheikh
    University West, Department of Engineering Science.
    Programming a robot arm using teaching method by using machine vision and sensor technology2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of robot has a major part in all kinds of industry (food, textile, automobile, agriculture, space and so on). With the increase of robot in industry, robot programming is also becoming more and more important, and more complex, therefor not accessible to anyone. The common way to program robot is by using programming languages, to communicate with the robot and its different element, and simulation, to observe the robot behaviour in a simulated environment before using a tangible one. Programming languages can be tedious, especially robot programming, which means that it can only be done by someone with the proper knowledge and education, making robot programming almost impossible to understand for non-robot programmers. To tackle this issue, a simpler programming method has been implemented during this thesis work, by combining machine vision and sensor technology. The idea is to track, using machine vision movement of a human arm, and use sensors, in this case a gyroscope, to register the orientation of the arm. The conclusion of this work shows us that the method investigated and developed, could allow a user, to manipulate an industrial robot, without knowing anything about robot or robot programming. Although, this method can be enhanced, by recording the movement done by the user, so that it can reproduce it for different work, by using an accelerometer tomove the robot at the same speed as the human hand. 

  • 260.
    Awasthi, Shikha
    et al.
    Material Science and Engineering, Indian Institute of Technology, Kanpur, Kanpur, India .
    Goel, Sneha
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Pandey, Chandra Prabha
    Babu Banarasi Das University, Department of Chemistry, Lucknow, India.
    Balani, Kantesh
    Material Science and Engineering, Indian Institute of Technology, Kanpur, Kanpur, India .
    Multi-Length Scale Tribology of Electrophoretically Deposited Nickel-Diamond Coatings2017In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 69, no 2, p. 227-235Article in journal (Refereed)
    Abstract [en]

    Electrophoretically deposited (EPD) nickel and its composite coatings are widely used to enhance the life span of continuous ingot casting molds in the steel, aerospace and automotive industries. This article reports the effect of different concentrations of diamond particles (2.5–10 g/L) on the wear mechanism of EPD Ni. The distribution of diamond particles in the Ni matrix was observed using Voronoi tessellation. Variation in COF was observed by a fretting wear test to be 0.51 ± 0.07 for Ni, which decreases to 0.35 ± 0.03 for the Ni-diamond coatings. The wear volume of the coatings with 7.5 g/L concentration of diamond was observed to be a minimum (0.051 ± 0.02 × 10−3 mm3) compared with other composite coatings. Further, the micro-scratch testing of the coatings also exhibited a reduced COF (0.03–0.12) for 7.5 g/L diamond concentration compared with Ni (0.08–0.13). Higher wear resistance of the diamond-added coatings (optimum 7.5 g/L concentration) is due to the balance between the dispersion strengthening mechanism and the enhancement of the load-bearing capacity due to the incorporation of diamond particles. Thus, these composites can be used for applications in automotive and aerospace industries. © 2016 The Minerals, Metals & Materials Society

  • 261.
    Axelsson, Daniel
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Olsson, Daniel
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Utvärdering av olika dynamiska lastmodeller i PSS/E2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor’s thesis has been performed for Vattenfall Eldistribution AB. The purpose of this work has been to create understanding of dynamic load models and clarify how they function and how they can be used. The aim has been to perform simulations on short circuits and motor starts for two different load models. A part of the work is also to describe the basic principles of the induction motor to create a connection between simulation and theory. The theory of the induction motor contains information about the electric induction that is the basic principle of the induction machine. It also contains the correlations between torque, speed, current and voltage and also a description of the equivalent electric circuit. The IMD program is a program connected to PSS/E and it has been used to create the model for the induction motor that has been used for the simulations. The simulations have been based on instructions from the advisor and instructions from the PSS/E manuals. Simulations have been run with two of the built-in load models in PSS/E, one general load model and one model for induction motors. Short circuits have been simulated on both models and motor starts on the induction motor model. Short circuits have been simulated with two different fault durations 0.15 and 0.4 seconds. Motor starts have been simulated with two different transformer sizes 1.5 and 3.0 MVA and three different values of the inertia time constant 0.7, 1.0 and 1.5 MWs/MVA. At short circuit the fault duration causes larger currents and longer recovery times for both load models. At motor start the size of the transformer, in MVA, and the inertia time constant affects the motors starting time. Larger transformer means shorter time because of lesser drop in voltage. A larger inertia time constant means longer time.  If only the size of the voltage drop is of interest and not the course of the event, the motors start admittance can be used instead.

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  • 262.
    Axelsson, Robin
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Wangerås, Simon
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Övertagande av huvudmannaskap för allmän plats: En studie av kommuner som behandlat frågan kring övertagande av huvudmannaskap för allmän plats i detaljplan2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The study's 13 municipalities who want or have treated the matter of the choice of the mandatorship for the public space in new and existing detail plans. In Boverkets spaning - Huvudmannaskap innebär svårigheter, they mentioned several problems were arising in detailed with individual mandatorship, for example, no specific reasons for setting up zoning with individual mandatorship, it appears that municipalities do not plan areas that obviously would otherwise be used as a public place. Injustice arises when property owners have to pay construction and maintenance of the road in a public place while they pay municipal taxes that finance public places. Problems in implementation was identified in plans with individual mandatorship. The thought out community unions does not tend work in practice.

    With these problems a thorough study of the problems municipalities had with individual principal responsibility of the plans have been completed, treating how it is supposed to implement a change from the individual to the municipal mandate for the public space.

    The purpose of the study is to examine these municipalities that dealt with the issue surrounding the principal responsibility for the public space in plans. Furthermore to investigate whether the municipality experienced problems with individual principal responsibility for the general location based on the information that Boverket mentions in the spaning - Huvudmannaskap innebär svårigheter. The aim is to examine how local authorities are performing a change from individual mandatorship to municipal mandate in new and existing plans.

    The study was conducted according to a cross-sectional design, which means that both a survey and interviews were used. To find out which municipalities we could use in our study we sent out a survey, 21 municipalities were selected from the answers and 13 of these municipalities were interviewed.

    The result shows that most municipalities want to make a change based on similar grounds. Municipalities have different ways of dealing with the transition from the individual to the municipal mandate in the plans but the most common way is to change the existing plan. In summary, we think it is positive that municipalities address the issue surrounding the principal responsibility. We believe that the majority of municipalities handle the problems properly and make decisions based on the right reasons.

  • 263.
    Ayaad, Abed-e
    University West, Department of Engineering Science, Division of Automation Systems.
    AGV solution in production lines2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project describes and discusses the technical issues and the benefits of using the auto-mated guided vehicles (AGVs) solution in production lines to take care of materials handling system in order to increase the flexibility and productivity of a manufacturing system.

    This work started with literature study on AGVs in general and gathering information about existing technologies from the previous and ongoing researches. This gathered knowledge has been used as a base to the practical work. The main aim of the practical work is to implement an AGV in the production line at PTC at University West. In order to per-form the implementation a guidance loop of magnetic tape has been designed. To achieve the goal of this work several tests and experiments have been done to evaluate the validation of the modeled AGV system.

  • 264.
    Aydin, Faruk
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Jasem, Anas
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Batterier som reservkraft i lågspänningsnät med solceller2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This bachelor’s thesis is written as a case study where the intended purpose is to reduce emissions of fossil fuels from a diesel generator and to ensure that Trollhättan Energi AB's customers receive an uninterrupted electricity supply during island operation. This is done by replacing diesel generators with chargeable batteries. 

    The identified problem occurs when Trollhättan Energi AB uses a diesel generator in a substation where solar cells are also connected, and the solar cells produce more power thanthe costumers consume. This surplus power from solar cells will result in a disconnection of the diesel generator due to reverse power protection.

    The battery capacity would need to be relatively large to cope with all the possible scenarios. For the use of battery only, the study limits the time intervals between sunrise and sunset to reduce the need for larger battery capacity. However, outside this time interval, an ordinary generator with environmental fuel HVO 100 is assumed to be used in parallel and therefore two different battery capacities were examined. Capacity for the batteries are 245 kWh and 490 kWh, respectively.

    The method is to find a charging level for the batteries that can adapt to different seasons. Since the power consumption is not the same in June as in February, the battery charging level is different for the different months. The results of the study show that with a battery capacity of 245 kWh, Trollhättan Energi AB must contact the solar cell owner during island operation to avoid interruptions. The battery capacity 490 kWh can handle island operation at all time intervals for the risk of back power throughout the year without having to contact the solar cell owner.

    Buying a 490 kWh battery costs approximately 400 kSEK / year over 15 years. It is expensive and not profitable to solve the problem with the reverse power. In the future, however, if the battery price is lowered and the number of solar cell systems increases, it may become more profitable. The easiest and cheapest solution today is to order the owners of the solar cell systems to switch of the power production and then use a diesel generator, as today. In Trollhättan, the number of solar cell installations is increasing, and this means that in the future it might be a more significant problem for Trollhättan Energi AB. If several customers install solar cells and a spontaneous interruption occurs, it will be more challenging to contact and organize a solar cell switch-off with all costumers. Therefore, buying a battery might be a solution in the future.

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  • 265.
    Aydin, Gökçe
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Valiente Bermejo, Maria Asunción
    University West, Department of Engineering Science, Division of Welding Technology.
    Högström, Mats
    University West, Department of Engineering Science, Division of Welding Technology.
    Şelte, Aydın
    Uddeholms AB, Hagfors (SWE).
    Oikonomou, Christos
    Uddeholms AB, Hagfors (SWE).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Influence of laser metal deposition process parameters on a precipitation hardening stainless steel2023In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 67, no 4, p. 1067-1080Article in journal (Refereed)
    Abstract [en]

    The combination of corrosion resistance and mechanical properties of martensitic precipitation hardening stainless steels (MPHSS) makes them well suited for demanding applications in aerospace, high-pressure gas bottles, or in injection molding of corrosive plastics. Directed energy deposition methods and specifically the laser metal deposition process with powder as feedstock (LMDp) have the potential to be applied in the production of such components. It is well-known that the geometrical features of the deposited beads such as aspect ratio and dilution are crucial for process efficiency and deposition quality. Therefore, this work aims at understanding the influence of the process parameters and the resulting microstructure of a MPHSS modified PH 13-8Mo alloy when using LMDp. Design of experiment (DoE) was used to plan and analyze the influence and interaction of the different LMDp process variables in the geometry of the deposits. It was found that height, width, and depth were statistically significantly influenced by speed, while height was also considerably influenced by the powder feeding rate. In terms of laser power, it was the most significant factor for the width and the depth, but it did not significantly affect the height of the beads. The results showed that the as-deposited microstructure of the modified PH 13-8Mo under the LMDp conditions investigated in this work consists of a martensitic matrix with some amount of primary δ ferrite. The presence of a low amount of retained austenite and aluminum-enriched inclusions was confirmed. This work enhances the fundamental process and material understanding of LMDp of the modified PH 13-8Mo alloy as a first stage in the fabrication of additively manufactured components.

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  • 266.
    Aydin, Gökçe
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Şelte, Aydın
    Uddeholms AB, Hagfors (SWE).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Valiente Bermejo, María Asunción
    University West, Department of Engineering Science, Division of Welding Technology.
    Towards Laser Metal Deposition of Modified PH 13-8Mo Powder2023In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 964, p. 85-90Article in journal (Refereed)
    Abstract [en]

    Modified PH 13-8Mo alloy exhibits a good combination of corrosion resistance and mechanical properties for demanding applications in aerospace, petrochemical, and tooling industries. Additive manufacturing, specifically the laser metal deposition process with powder as feedstock (LMDp), has the potential to be utilized in these industries. However, very limited knowledge on the LMDp of this alloy currently exists. The aim of this work was, therefore, to deposit a multi-track single layer of modified PH 13-8Mo alloy as a first step towards 3D geometries, and to analyze the resulting microstructure by using Optical Microscopy, Scanning Electron Microscopy, X-Ray Diffraction, Electron Backscatter Diffraction, and micro-hardness. It was found that the multitrack single layer was free from major defects. The microstructure was heterogeneous, and it consisted of a martensitic matrix and small amounts of δ ferrite, austenite, and AlN. The results of this research will be used to tailor the microstructure and properties of future 3D additively manufactured components.

  • 267.
    Azar, Amin S.
    et al.
    SINTEF Mat & Chem, Oslo, Norway.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Production Engineering.
    Nyhus, Bård
    SINTEF Mat & Chem, Oslo, Norway.
    Effect of crystal orientation and texture on fatigue crack evolution in high strength steel welds2015In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 77, p. 95-104Article in journal (Refereed)
    Abstract [en]

    In the present study, electron backscattered diffraction is used to analyze the fatigue crack evolution in a high strength steel weld that was loaded cyclically in the plastic regime. Three prominent regions of a fatigue crack are investigated separately: crack tip, crack trajectory and crack initiation. Taylor and Schmid factors are mapped with respect to the defined loading matrix. Possible effective mechanisms are proposed based on the local plasticity properties like lattice rotation and misorientation. The analyses of the crack tip and trajectory regions show that although the critical resolved shear stresses in some regions are low, small deformation resistance of these regions can compromise the dislocation immobility and cause local fracture. It is shown that if the crack grows transgranularly, at least one side of the crack may show low lattice rotation or strain equivalent values, which indicates the relaxation of elastic stresses after fracture. The crack initiation is determined to be dominantly controlled by transcrystalline mechanism of initiation that takes place under plastic loading conditions. It is also shown that the secondary < 123 >11 (1) over bar type of slip systems were the most activated under such loading conditions. (C) 2015 Elsevier Ltd. All rights reserved.

  • 268.
    Aziz, Hakar
    et al.
    University West, Department of Engineering Science.
    Linder, Jonatan
    University West, Department of Engineering Science.
    Visualization boards and their applications in manufacturing and daily management2022Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With digitalization becoming increasingly more important in the way that companies can increase their efficiency by allowing the employees to see the production in the way of visualization. This thesis explores how the design and implementation of digitalized visualization board in the form of the Mevisio platform can help Sansera streamline their production. The data collection was performed through daily communication with the workers and qualitative interviews. The results gathered from the communication and interviews showed that there was a lot of unnecessary information. The machine operators only cared about how much they had produced and how much they would and that it should be as simple as possible. Another thing gathered from the interviews was that it was easy to make errors when they used to visualize everything on whiteboards and paper. The conclusion was that with the help of a digitalized visualization board tailored for their needs they could more easily pay attention to the problems that arise and decrease the risk of human errors.

  • 269.
    Aziz, Jamal
    University West, Department of Engineering Science.
    Assessing the recycling of cathodes in Physical Vapor Deposition systems to promote circularity and sustainability2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Climate change, because of greenhouse gas (GHG) emissions from human activities, has become a critical issue as it is affecting our environment. According to the Paris Agreement, an international agreement on reducing GHG emissions and addressing climate change, it was agreed that global warming should be kept below 2°C above the preindustrial level and preferably at 1.5°C. To be able to reach this goal, countries and non-state entities, such as companies and individuals, are making efforts to reduce GHG emissions. In this respect, as with many other companies, Seco Tools AB has a goal to reduce 50% of its GHG emissions by 2030 and reach net zero emissions by 2050.

    This study was conducted with the aim of determining and understanding the impact of GHG emissions in physical vapor deposition (PVD) coating production. In addition, to potentially increase the use of materials and reduce GHG emissions, a study was done on the effect of recycling cathode (target) materials on the process, microstructure, and properties of TiAlN coating. The analysis was performed to determine how much CO2 emissions can be avoided by recycling cathode materials.

    The boundaries selected for the estimation of GHG emissions are the use of electrical energy, water, process gases, and cathode materials during the process. The present study shows that the PVD coating process emits about 13.76 kg CO2 to produce a standard batch of TiAlN coating. The shares of emissions from cathode materials, electrical energy, water, and process gases are 76%, 17%, 6%, and 1%, respectively.

    The effect of recycled materials on the process, microstructure, and properties of TiAlN coatings produced by cathodic arc deposition was investigated. The coatings were grown with varying chemical compositions from recycled cathodes on cemented carbide substrates at different substrate bias voltages (-25 V, -45 V, and -65 V). The coating thickness, adhesion strength, microstructure, macroparticle presence, phase formation, and residual stress of coatings were investigated and compared with those produced with virgin cathodes, and the results were found to be similar. The coatings showed excellent adhesion strength, and the thicknesses ranged from 1.9 to 3.2µm. The cross-sectional micrographs revealed that the coatings exhibit dense columnar microstructures and the presence of microparticles. Applying a higher bias voltage resulted in coatings with fewer microparticles and increased compressive residual stresses. Phase analysis by X-ray diffraction indicated that a single cubic phase was formed in the coatings. 

    The analysis of the impact of cathode recycling on GHG emissions reduction revealed that a proper recycling procedure can potentially reduce 9.70 kgCO2 per batch.

  • 270.
    Babu, Bijish
    et al.
    Mechanics of Sold Materials, Luleå University of Technology, SE-971 87, Luleå, Sweden.
    Charles Murgau, Corinne
    University West, Department of Engineering Science, Avdelningen för svetsteknologi (SV).
    Lindgren, Lars-Erik
    Mechanics of Sold Materials, Luleå University of Technology, SE-971 87, Luleå, Sweden.
    Physically Based Constitutive Model of Ti-6Al-4V for Arbitrary Phase CompositionArticle in journal (Other academic)
    Abstract [en]

    The main challenge in producing aerospace components using Ti-6Al-4V alloy is to employ the optimum process window of deformation rate and temperature in order to achieve desired material properties. Understanding the microstructure property relationship qualitatively is not enough to achieve this goal. Developing advanced material models to be used in manufacturing process simulation is the key to iteratively computeand optimize the process. The focus in this work is on physically based flow stress models coupled with microstructure evolution models. Such a model can be used to simulate processes involving complex and cyclic thermo-mechanical loading

  • 271.
    Babu, Challa
    et al.
    Department of EEE, Siddartha Institute of Science and Technology, Puttur, AP (IND).
    Immanuel, A.
    Department of EEE, Audisankara College of Engineering and Technology, Gudur, AP (IND).
    Jyotheeswara Reddy, K.
    School of EEE, REVA University, Bangalore, Karnataka (IND).
    Kumar, K.
    Department of EEE, SV College of Engineering, Tirupathi, AP (IND).
    Ramasamy, Sudha
    University West, Department of Engineering Science, Division of Production Systems.
    Venkateswarlu, S.
    School of Electrical Engineering, VIT University, Vellore (IND).
    Performance analysis of flat plate hybrid PV/thermal configurations2022In: AIP Conference Proceedings, American Institute of Physics (AIP), 2022, Vol. 2461, article id 060007Conference paper (Refereed)
    Abstract [en]

    In the recent times many hybrid renewable energy sources are developed. In that, hybrid PV/Thermal gains the more attention than other hybrid sources. In the present work, made a performance analysis of different PV/Thermal configurations. The flat plate configurations have the more feasibility for the domestic applications than the concentrated type. In this paper, liquid, air, nano fluid, phase change material and Thermoelectric generator type configurations are presented. The performance analysis of all configurations done with energy output generation and efficiency of the system. 

  • 272.
    Babu, Challa
    et al.
    Audisankara college of engineering and technology, Department of electrical and electronics engineering, Gudur, A.P, India (IND).
    Kumar, D. Dinesh
    Audisankara college of engineering and technology, Department of electrical and electronics engineering, Gudur, A.P, India (IND).
    Kumar, K
    SV College of Engineering, Tirupathi, AP, India (IND).
    Reddy, K Jyotheeshwara
    Sree Vidayanikethan Engineering College, Tirupathi, A.P., India (IND).
    Ramasamy, Sudha
    University West, Department of Engineering Science, Division of Production Systems.
    Power Monitoring and Control System for Medium Voltage Smart Grid Using IoT2020In: IOP Conference Series: Materials Science and Engineering, IOP Publishing , 2020, Vol. 906, article id 12007Conference paper (Refereed)
    Abstract [en]

    This paper presents a power monitoring and control system for a medium voltage smart grid system. The smart grid interconnects the power sources between solar PV panel and 220V distribution network. This system consisting major components of inverters, measuring meters, solar charge controllers, relays, Arduino NANO and Raspberry Pi. The Current, power and energy readings are duly recorded. The Internet of Things (IoT) plays the vital role in the data communication between the sensors and electric power system. The voltage and current sensor data is used for the protection of power system network. In the traditional systems only the communication is uni-directional. The reliability of power supply is increased by used the bi directional network communication medium such as IoT. The tabulated results of voltage levels between 203.5V up to 212.8V shows the feasibility and effectiveness of proposed design. The proposed IoT model demonstrated the bidirectional communication from the sensors to the control unit and vice versa.

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  • 273.
    Bachmann, Gabriel
    et al.
    University West, Department of Engineering Science.
    Göbel, Niklas
    University West, Department of Engineering Science.
    Evaluation of requirements for measurement technology in mobile hydrogen applications including associated infrastructure with the aim of creating recommendations for measuring devices2022Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this master thesis is to point out where pressure and temperature measuring devices can be implemented in the hydrogen production, supply chain, storage system, refuelling station and in a hydrogen vehicle. For this reason, a basic knowledge for hydrogen as a chemical element and energy carrier in a vehicle has to be gained. Moreover, production methods, storage systems and the supply chain of hydrogen are described.

    It has been shown that in order to ensure safe and stable processes it is indispensable to measure pressure and temperature in the entire hydrogen chain from the production right through to the energy conversion in a vehicle. On the basis of these results, the requirements and type approval processes of measuring devices in mobile hydrogen applications including associated refuelling stations are analysedto ensure a safe and reliable market entry for manufacturers. Special attention will be paid to possible challenges while measuring state sizes of hydrogen.

    It has turned out that the European main standard EC79/2009 that regulates requirements and type approvals of components in mobile hydrogen applications will be repealed in July 2022. To find an adequate alternate standard, the American regulation HGV 3.1 is analysed in regards to commonalities and differences to EC79/2009. The result of the comparison is that in terms of type approvals for components in compressed gaseous mobile hydrogen applications HGV 3.1 scopes most of the relevant contents of EC79/2009 and can therefore be used as an alternative. However, when it comes to components for liquid hydrogen contact in mobile hydrogen applications there are no alternatives to the European standard. For this reason, until the gap is closed by a new international standard, manufacturers for components with liquid hydrogen contact have to refer to certain requirements of EC79/2009 but approve products according to valid regulations like HGV 3.1.

    Finally, the analysis of requirements and type approvals for components used in refuelling stations according to ISO 19880-1 showed that close arrangements between customer and manufacturer is indispensable to ensure a smooth process.

  • 274.
    Back, Cornelia
    et al.
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Gustafsson, Julia
    University West, Department of Engineering Science, Division of Computer, Electrical and Surveying Engineering.
    Kartläggning av Stockholms, Göteborgs och Malmös hantering av miljonprogramsområden: ur kommunernas och de kommunala bostadsbolagens perspektiv2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The million programme is a building era that took place between the years 1965 to 1974 when a politic decision was made to build a million new residences in Sweden, to correct the housing shortage. It´s now been more than 40 years since these residences were built and the need to renovate is a necessity, which makes this programme a very current subject. The purpose of this study is to map the three largest city´s handling of the need for renovation. The main question of this study is how the buildings of the million programme is being handled today. Meanwhile a series of other questions have been answered in this study; the difference between laws now and then, how the million programme areas looks in the different cities and how they are treated in the layout plans, what the need for renovation might lead to, and if there is any profit in restoring the buildings.It is a qualitative study as it is a situation in a few cities that are being studied, but through a survey this study gets a quantitative mixture as well. A survey was dispatched to the three municipalities and their communal real estate companies.Malmo, Gothenburg and Stockholm are both similar and different regarding planning and visions. Both Gothenburg and Stockholm placed their million programmes outside of the city´s core, whilst Malmo´s was located close to the centre of the city. They all have visions in their layout plans to create a more unified and connected city through increased integration and better communication between the city areas.There was a wave of renovation in the eighties and nineties because of the ROT-deduction and many projects concerning the million programme are still ongoing to this day. Facade renovation is common in all three cities and, to a certain degree, restoration of balconies and windows. Gothenburg has invested a lot in energy efficient measures and in Stockholm it has become increasingly more common with energy saving interventions like adding increased isolation. The image of the million programme´s constructions is "concrete ghettos", but the most common houses consists of three storeys with apartment size 3 rok.The Swedish legislation are of great importance during the renovation as there now are requirements on energy efficiency amongst other things, but also during the wave of renovation in the eighties and nineties when the demand of discretion was enforced in PBL 1987. The foundation in the million programme houses is satisfactory and they are functionally built which makes a renovation more cost-efficient than it would be to tear it down and build new buildings. The problem then does not reside in the need for renovation, as most houses needs restoration after so many years, but in the sheer number of buildings that would require a renovation.

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  • 275.
    Backelin, Christoffer
    University West, Department of Engineering Science, Division of Mechanical Engineering and Natural Sciences.
    Experimental study of trepanning process with nickel-base superalloy sheet, using CO2 laser.2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis experimentally investigates the defect generated at the start and stop zone when trepanning, using CO 2 laser and the nickel-base superalloy Hastelloy X. The project has been performed at Siemens Industrial Turbomachinery AB (SIT) in Trollhättan. Experiments which investigates the effect of altering entrance radius, exit radius (withdrawal) and nozzle distance have been performed. Samples were created by using a Trumpf 2D-laser machine and they were prepared for evaluation by grinding, polishing and etching. The Sample were then evaluated and measured by using an optic microscope. Experiments have been planned according to the method, design of experiments (DOE).

    By using the programme Minitab, regression analysis and empirical models were created which describes the effect of the tested parameters. The results show that it is possible to decrease the start and stop defects by altering of the process parameters.

  • 276.
    Backersgård, Oscar
    et al.
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Gustavsson, Christoffer
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    Undersökning av Trimbles etableringsmetoder vid fri station: en jämförelsestudie av integrerad etablering och etablering med kända punkter2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the comparison between two different methods of establishment of free station for the purpose of geodetic surveying. The methods are the traditional method,with known control points with already established coordinates, and the integrated method,that uses GNSS-technology. In the beginning of the thesis there is some theoretical background and explanation of the technology and methods to help with understanding the later parts. The study focuses only on the accuracy of the different methods, and not the time that each method takes to establish. This was decided because the main interest was to see which method was the most accurate, and not the most efficient time wise.

    The method using known points is based on using points that have already established coordinates, and by measuring the distances and angles between these and the total station a position for the total station can be calculated. The other method is based on GNSS, and also uses the total station. This method instead uses new points, known as backsights, that are placed out during the establishment. The thesis also focuses on the sources of error that can occur during work with these methods, and how these sources impact the different methods. A look into the geodetic control network is also made and discussed throughout the thesis.In the end the completed results from all of the establishments are compiled and summarized, and a comparison and analysis are made on these results. These results are later discussed and the strengths and weaknesses of each method is weighed up.

    The results of this study has shown that the best quality of the establishment is reached by using the integrated with at least five backsights. The sources of errors that were discovered for each method are studied more closely, in correlation to the prerequisites of the study. The study also shows that some of the known control points that were used during the establishments were of bad quality and in need of a control and some adjustments, to ensure that future work around these points won’t be a problem.

    In the conclusion of the study the result shows that the use of the integrated method withat least five backsights is the preferred method of establishment. The quality of the establishment with the integrated method was 0,002 m and 0,004 m for the north and east coordinates, while the result of the traditional method was 0,004 and 0,013 for the north and east coordinates.

  • 277.
    Bader, Mirjam
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Nuur, Ilham
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    En logistikstudie med fokus på faktorer inför implementering av produktionsflödessimulering: Siemens Industrial Turbomachinery AB2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During a ten-week period, in the spring term of 2020, a thesis project was carried out with the aim of creating an understanding of how production flow simulation can be used as a sustainable activity to plan production and achieve more efficient planning at Siemens Industrial Turbomachinery AB in Trollhättan. The aim of the study was to examine the differences between planned production times in the enterprise resource planning system and the reported production time and to propose a flow simulation model that can be reused to achieve a more balanced production flow.

    The problem situation that formed the basis of the study was that there is uncertainty as to whether the reported time corresponds to the times planned in the enterprise resource planning system. The company has also lifted aspects such as long waiting times, high buffer and storage levels between operations, long transport distances and a large number of work in progress (WIP). With a more accurate production planning, these problem areas can be highlighted and with time, reduce waiting times and WIP.

    The data that formed the basis for the thesis work was provided by the company and production times and logistical aspects were calculated and analyzes. After the analyzes, results showed that there are differences between the planned and the reported production times. Thus, it can be concluded that regular follow-up of the reported data should be initiated at the company to improve understanding of why there are discrepancies between planned and reported times, and to work towards reducing the gap between planned and reporting production times. The results also showed more trends regarding production times and logistics aspects, such as increased production times during the year, a bottleneck in production was discovered and how much of the total lead time that is value-creating in the internal process was highlighted.

    Based on the results that focused on outlining the production flow, a conceptual simulation model was built that visualizes the production, which is a starting point for further development and use of production flow simulations. It was concluded that the data collection aspects and its analysis were of large importance for preparation of building the model. It is of great value to have good insight into the production flow of the company and the conclusion stresses the importance of a detailed study of the production flow and to understand the production data before deciding on whether a simulation model should be built and the scoop of that model.

  • 278. Badgujar, A. C.
    et al.
    Dhage, S. R.
    Joshi, Shrikant V.
    Process parameter impact on properties of sputtered large-area Mo bilayers for CIGS thin film solar cell applications2015In: Thin Solid Films, Vol. 589, p. 79-84Article in journal (Refereed)
    Abstract [en]

    Copper indium gallium selenide (CIGS) has emerged as a promising candidate for thin film solar cells, with efficiencies approaching those of silicon-based solar cells. To achieve optimum performance in CIGS solar cells, uniform, conductive, stress-free, well-adherent, reflective, crystalline molybdenum (Mo) thin films with preferred orientation (110) are desirable as a back contact on large area glass substrates. The present study focuses on cylindrical rotating DC magnetron sputtered bilayer Mo thin films on 300 mm × 300 mm soda lime glass (SLG) substrates. Key sputtering variables, namely power and Ar gas flow rates, were optimized to achieve best structural, electrical and optical properties. The Mo films were comprehensively characterized and found to possess high degree of thickness uniformity over large area. Best crystallinity, reflectance and sheet resistance was obtained at high sputtering powers and low argon gas flow rates, while mechanical properties like adhesion and residual stress were found to be best at low sputtering power and high argon gas flow rate, thereby indicating a need to arrive at a suitable trade-off during processing. © 2015 Elsevier B.V.

  • 279.
    Badgujar, Amol C.
    et al.
    Centre for Solar Energy Materials, ARCI, Hyderabad, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Dhage, Sanjay R.
    Mechanical and Aerospace Engineering Department, University of California, Los Angeles, USA .
    Process Parameter Impact on Selective Laser Ablation of Bilayer Molybdenum Thin Films for CIGS Solar Cell Applications2018In: Materials focus, ISSN 2169-429X, no 4, p. 556-562Article in journal (Refereed)
    Abstract [en]

    Cu(In,Ga)Se2 or CIGS absorber layers are a promising candidate for thin film solar cells, with efficiency exceeding 22% having already been demonstrated at the cell level and their commercialization been ramped up. Scribing by selective ablation to achieve monolithic integration is an essential step in CIGS module making to divide a large area cell into a series of inter-connected smaller cells. P1 scribing or electrical isolation of back contact is an essential part of the monolithic integration. Laser-induced scribing of Molybdenum (Mo) back contact of a CIGS solar cell is highly sensitive to process parameters like laser power, pulse duration, and pulse repetition frequency. The above parameters control the scribe width, heat affected zone and process residue directly or indirectly, thereby affecting electrical isolation and module performance. Influence of laser process parameters on scribing of a bilayer Mo thin film back contact has been investigated and is being reported. The scribes obtained employing various laser conditions were characterized for electrical isolation and analyzed by optical microscopy followed by profilometry. High-quality scribing, with a scribe width of 53 μm over a length of 300 mm, was achieved on a bilayer Mo thin film sputtered on a Soda lime glass substrate.

  • 280.
    Baga, Moustafa
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Demeter, Janos
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Undersökning av hårdhet på pulverbäddtillverkad superlegering 247 LC2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Alloy 247 LC is a material that is used in manufacturing for making gas turbine blades and is made of nickel. Due to that the material in the blade has a high strength at high temperatures and a melting point higher than 1200 °C, is the blade can be used in the warmest/hottest sections of jet engines and turbines. The efficaciousness of the motors depends on the temperatures, and the higher temperature the more efficiency. This induces a cut/saving of fuel. Nowadays the blades are made of casting which brings a big effort in both time, labor, and material. To make the production of Alloy 247 LC more effective the research is in progress and focuses on how the product can be performed with different methods. One of these methods is called additive manufacturing which is also called 3D print. This method includes laser powder bed fusion (L-PBF) and implies laser-based melting in powder bed. Laser powder bed fusion is a process that simplifies the production of very complex shapes of blades which can be problematic during the manufacturing in casting. The most important characteristics of Alloy 247 LC is the strength and hardness. Hence, it is important that these features are preserved also during laser powder bed fusion. The purpose of this study is to measure the hardness at Alloy 247 LC which is manufactured through laser powder bed fusion (L-PBF) in additive manufacturing and subsequently compare the result of hardness values with the given hardness values that the casting has. This to investigate if these features are preserved through laser powder bed fusion (L-PBF) due to that the most important characteristics of Alloy 247 LC are strength and severity. We used 36 test cubes with the dimensions of 15x15x15 mm. The cubes were produced with/through laser powder bed fusion with varying process parameters on power and speed to and arrive at the most suitable for the hardness of the material. The cubes were divided into three pieces each which implicated that we had 108 pieces for the test. Thereafter the result from the hardness values was compared with the hardness values from the casting. To get a deeper understanding of the results of hardness values, all of the pieces from the test were analyzed with the help of optical microscope. Further four pieces from the test were chosen and also observed in a scanning electron microscope in order to examine the microstructure. The conclusion in the study was that laser powder bed fusion (L-PBF) can be a suitable method if used with the right process parameters.

  • 281.
    Baghdadchi, Amir
    University West, Department of Engineering Science, Division of Welding Technology.
    Directed Energy Deposition Additive Manufacturing and Welding of Duplex Stainless Steel using Laser Beam2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Duplex stainless steels (DSSs), with a ferritic-austenitic microstructure, are used in a wide range of applications thanks to their high corrosion resistance and good mechanical properties. However, efficient and successful production and joining of DSS require precise control of processes and an in-depth understanding of the relations between composition, processing thermal cycles, resulting microstructures and properties. In this study welding and direct energy deposition of DSS using a laser beam, resulting weld and component microstructures, and properties are explored.

    In the first part a lean FDX 27 DSS, showing the transformation-induced plasticity (TRIP) effect, was autogenously laser welded and laser reheated using pure argon or pure nitrogen as shielding gas. The weld metal austenite fraction was 22% for argon-shielding and 39% for nitrogen-shielding in the as-welded conditions. Less nitrides were found with nitrogen-shielding compared to argon-shielding. Laser reheating did not significantly affect nitride content or austenite fraction for argon-shielding. However, laser reheating of the nitrogen shielded weld removed nitrides and increased the austenite fraction to 57% illustrating the effectiveness of this approach.

    Phase fraction analysis is important for DSS since the balance between ferrite and austenite affects the properties. For TRIP steels the risk of austenite-to-martensite transformation during sample preparation also has to be considered. Ferrite, austenite and martensite were identified and quantified using light optical microscopy (LOM) and electron backscatter diffraction (EBSD) analysis. It was found that mechanical polishing produced up to 26% strain-induced martensite, while no martensite was observed after electrolytic polishing.

    In the second part a systematic four-stage methodology was applied to develop procedures for additive manufacturing of standard 22% Cr DSS components employing direct energy deposition using a laser beam and wire feedstock (DED-LB/w) combined with the hot wire technology. In the four stages, single-bead passes, a single-bead wall, a block, and finally a cylinder with an inner diameter of 160 mm, thickness of 30 mm, and height of 140 mm were produced. Implementing this methodology with a stepwise increase in the deposited volume and geometrical complexity can successfully be used when developing additive manufacturing procedures for significantly sized metallic components. The as-deposited microstructure was inhomogeneous and repetitive including highly ferritic regions with nitrides and regions with high fractions of austenite. Heat treatment for 1 hour at 1100°C homogenized the microstructure, dissolved the nitrides, and almost balanced the ferrite and austenite phase fractions. Strength, ductility, and toughness were at a high level for the cylinder, comparable to those of wrought type 2205 steel, both as-deposited and after heat treatment. The pitting corrosion resistance revealed that microstructural differences, including ferrite-to-austenite ratio, alloying element distribution in ferrite and austenite , and the presence of nitrides, affected the corrosion resistance of DED-LB/w DSS. It was also shown that alongside the decomposition of ferrite into Fe-rich (α) and Cr-rich (αʹ) phases, clustering of Ni, Mn, and Si atoms are contributing to the 475°C -embrittlement of DSS manufactured by DED-LB/w.

    This study has illustrated that a laser beam can successfully be used as heat source in processing of DSS both for welding and additive manufacturing. However, challenges like nitrogen loss, low austenite fractions and nitride formation have to be handled by precise process control and/or heat treatment.

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  • 282.
    Baghdadchi, Amir
    University West, Department of Engineering Science, Division of Welding Technology.
    Laser Welding and Additive Manufacturing of Duplex Stainless Steels: Properties and Microstructure Characterization2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Duplex stainless steels (DSS), with a ferritic-austenitic microstructure, are used ina wide range of applications thanks to their high corrosion resistance and excellent mechanical properties. However, efficient and successful production and joining of DSS require precise control of processes and an in-depth understanding o frelations between composition, processing thermal cycles, resulting microstructures and properties. In this study laser welding, laser reheating, and laser additive manufacturing using Laser Metal Deposition with Wire (LMDw) ofDSS and resulting weld and component microstructures and properties are explored.

    In the first part a lean FDX 27 duplex stainless steel, showing the transformation induced plasticity (TRIP) effect, was autogenously laser welded and laser reheated using pure argon or pure nitrogen as shielding gas. The weld metal austenite fraction was 22% for argon-shielding and 39% for nitrogen-shielding in as-welded conditions. Less nitrides were found with nitrogen-shielding compared to argonshielding. Laser reheating did not significantly affect nitride content or austenite fraction for argon-shielding. However, laser reheating of the nitrogen shieldedweld removed nitrides and increased the austenite fraction to 57% illustrating the effectiveness of this approach.

    Phase fraction analysis is important for DSS since the balance between ferrite and austenite affects properties. For TRIP steels the possibility of austenite tomartensite transformation during sample preparation also has to be considered. Phases in the laser welded and reheated FDX 27 DSS were identified and quantified using light optical microscopy (LOM) and electron backscatter diffraction (EBSD) analysis. An optimized Beraha color etching procedure was developed for identification of martensite by LOM. A novel step-by-step EBSD methodology was also introduced, which successfully identified and quantified martensite as well as ferrite and austenite. It was found that mechanical polishing produced up to 26% strain-induced martensite, while no martensite was observed after electrolytic polishing.In the second part a systematic four-stage methodology was applied to develop procedures for additive manufacturing of standard 22% Cr duplex stainless steel components using LMDw combined with the hot wire technology. In the four stages, single-bead passes, a single-bead wall, a block, and finally a cylinder with an inner diameter of 160 mm, thickness of 30 mm, and height of 140 mm were produced. The as-deposited microstructure was inhomogeneous and repetitive including highly ferritic regions with nitrides and regions with high fractions ofaustenite. Heat treatment for 1 hour at 1100 ̊C homogenized the microstructure, removed nitrides, and produced an austenite fraction of about 50%. Strength, ductility, and toughness were at a high level for the cylinder, comparable to those of wrought type 2205 steel, both as-deposited and after heat treatment. The highest strength was achieved for the as-deposited condition with a yield strength of 765 MPa and a tensile strength of 865 MPa, while the highest elongation of 35% was found after heat treatment. Epitaxial growth of ferrite during solidification, giving elongated grains along the build direction, resulted in anisotropy of toughness properties. The highest impact toughness energies were measured for specimens with the notch perpendicular to the build direction after heat treatment with close to 300 J at -10oC. It was concluded that implementing a systematic methodology with a stepwise increase in the deposited volume and geometrical complexity can successfully be used when developing additive manufacturing procedures for significantly sized metallic components.

    This study has illustrated that a laser beam can successfully be used as heat source in processing of duplex stainless steel both for welding and additive manufacturing. However, challenges like nitrogen loss, low austenite fractions and nitride formation have to be handled by precise process control and/or heat treatment.

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  • 283.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Cary, Claire
    Department of Materials Science and Engineering, The Ohio State University, Columbus (USA).
    Sridhar, Narasi
    Department of Materials Science and Engineering, The Ohio State University, Columbus (USA).
    Valiente Bermejo, María Asunción
    University West, Department of Engineering Science, Division of Welding Technology.
    Fink, Carolin
    Department of Materials Science and Engineering, The Ohio State University, Columbus (USA).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Corrosion resistance and microstructure analysis of additively manufactured 22% chromium duplex stainless steel by laser metal deposition with wire2023In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 26, p. 6741-6756Article in journal (Refereed)
    Abstract [en]

    Microstructure characteristics and pitting corrosion of a duplex stainless steel (DSS) manufactured by laser metal deposition with wire (LMDw) were studied. The layer-by-layer LMDw process resulted in a mixed microstructure of predominantly ferrite with 2% austenite and chromium-rich nitrides, and reheated regions with ~33% austenite. The high cooling rate of LMDw restricted the distribution of Cr, Mo, and Ni, in ferrite and austenite, while N diffuses from ferrite to austenite. Subsequent heat treatment at 1100 C for 1 h resulted in homogenized microstructure, dissolution of nitrides, and balanced ferrite/austenite ratio. It also led to the redistribution of Cr and Mo to ferrite, and Ni and N to austenite. At room temperature, cyclic potentiodynamic polarization measurements in 1.0 M NaCl solution showed no significant differences in corrosion resistance between the as-deposited and heat-treated samples, despite the differences in terms of ferrite to austenite ratio and elemental distribution. Critical pitting temperature (CPT) was the lowest (60 C) for the predominantly ferritic microstructure with finely dispersed chromium-rich nitrides; while reheated area with ~33% austenite in as-deposited condition achieved higher critical temperature comparable to what was obtained after heat treatment (73 and 68 C, respectively). At temperatures above the CPT, selective dissolution of the ferrite after deposition was observed due to depletion of N, while after heat treatment, austenite preferentially dissolved due to Cr and Mo concentrating in ferrite. In summary, results demonstrate how microstructural differences in terms of ferrite-to-austenite ratio, distribution of corrosion-resistant elements, and presence of nitrides affect corrosion resistance of LMDw DSS.

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  • 284.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hosseini, Vahid
    University West, Department of Engineering Science, Division of Welding Technology.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Welding Technology.
    Karlsson, Leif
    University West, Department of Engineering Science, Division of Welding Technology.
    Promoting austenite formation in laser welding of duplex stainless steel-impact of shielding gas and laser reheating2021In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 65, p. 499-511Article in journal (Refereed)
    Abstract [en]

    Avoiding low austenite fractions and nitride formation are major challenges in laser welding of duplex stainless steels (DSS). The present research aims at investigating efficient means of promoting austenite formation during autogenous laser welding of DSS without sacrificing productivity. In this study, effects of shielding gas and laser reheating were investigated in welding of 1.5-mm-thick FDX 27 (UNS S82031) DSS. Four conditions were investigated: Ar-shielded welding, N2-shielded welding, Ar-shielded welding followed by Ar-shielded laser reheating, and N2-shielded welding followed by N2-shielded laser reheating. Optical microscopy, thermodynamic calculations, and Gleeble heat treatment were performed to study the evolution of microstructure and chemical composition. The austenite fraction was 22% for Ar-shielded and 39% for N2-shielded as-welded conditions. Interestingly, laser reheating did not significantly affect the austenite fraction for Ar shielding, while the austenite fraction increased to 57% for N2-shielding. The amount of nitrides was lower in N2-shielded samples compared to in Ar-shielded samples. The same trends were also observed in the heat-affected zone. The nitrogen content of weld metals, evaluated from calculated equilibrium phase diagrams and austenite fractions after Gleeble equilibrating heat treatments at 1100 °C, was 0.16% for N2-shielded and 0.11% for Ar-shielded welds, confirming the importance of nitrogen for promoting the austenite formation during welding and especially reheating. Finally, it is recommended that combining welding with pure nitrogen as shielding gas and a laser reheating pass can significantly improve austenite formation and reduce nitride formation in DSS laser welds. © 2020, The Author(s).

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  • 285.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hosseini, Vahid
    University West, Department of Engineering Science, Division of Welding Technology.
    Karlsson, Leif
    University West, Department of Engineering Science, Research Enviroment Production Technology West. University West, Department of Engineering Science, Division of Welding Technology.
    Identification and quantification of martensite in ferritic-austenitic stainless steels and welds2021In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 15, p. 3610-3621Article in journal (Refereed)
    Abstract [en]

    This paper aims at the phase identification and quantification in transformation induced plasticity duplex stainless steel (TDSS) base and weld metal containing ferrite, austenite, and martensite. Light optical microscopy (LOM) and electron backscatter diffraction (EBSD) analysis were employed to analyze phases. Samples were either mechanically or electrolytically polished to study the effect of the preparation technique. Mechanical polishing produced up to 26% strain-induced martensite. Electrolytic polishing with 150 g citric acid, 300 g distilled water, 600 mL H3PO4, and 450 mL H2SO4 resulted in martensite free surfaces, providing high-quality samples for EBSD analysis. Martensite identification was challenging both with LOM, due to the similar etching response of ferrite and martensite, and with EBSD, due to the similar lattice structures of ferrite and martensite. An optimized Beraha color etching procedure was developed that etched martensite distinctively. A novel step-by-step EBSD methodology was also introduced considering grain size and orientation, which successfully identified and quantified martensite as well as ferrite and austenite in the studied TDSS. Although here applied to a TDSS, the presented EBSD methodology is general and can, in combination with knowledge of the metallurgy of the specific material and with suitable adaption, be applied to a multitude of multiphase materials. It is also general in the sense that it can be used for base material and weld metals as well as additive manufactured materials.

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    JMR&T
  • 286.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hosseini, Vahid
    University West, Department of Engineering Science, Division of Welding Technology.
    Valiente Bermejo, María Asunción
    University West, Department of Engineering Science, Division of Welding Technology.
    Axelsson, Björn
    Alfa Laval Tumba AB, Tumba (SWE).
    Harati, Ebrahim
    University West, Department of Engineering Science, Division of Welding Technology. ITW Welding AB,Partille (SWE).
    Högström, Mats
    University West, Department of Engineering Science, Division of Welding Technology.
    Karlsson, Leif
    University West, Department of Engineering Science, Research Enviroment Production Technology West. University West, Department of Engineering Science, Division of Welding Technology.
    Wire laser metal deposition additive manufacturing of duplex stainless steel components -Development of a systematic methodology2021In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 14, no 23, article id 7170Article in journal (Refereed)
    Abstract [en]

    A systematic four-stage methodology was developed and applied to the Laser Metal Deposition with Wire (LMDw) of a duplex stainless steel (DSS) cylinder > 20 kg. In the four stages, single-bead passes, a single-bead wall, a block, and finally a cylinder were produced. This stepwise approach allowed the development of LMDw process parameters and control systems while the volume of deposited material and the geometrical complexity of components increased. The as-deposited microstructure was inhomogeneous and repetitive, consisting of highly ferritic regions with nitrides and regions with high fractions of austenite. However, there were no cracks or lack of fusion defects; there were only some small pores, and strength and toughness were comparable to those of the corresponding steel grade. A heat treatment for 1 h at 1100 degrees (C) was performed to homogenize the microstructure, remove nitrides, and balance the ferrite and austenite fractions compensating for nitrogen loss occurring during LMDw. The heat treatment increased toughness and ductility and decreased strength, but these still matched steel properties. It was concluded that implementing a systematic methodology with a stepwise increase in the deposited volume and geometrical complexity is a cost-effective way of developing additive manufacturing procedures for the production of significantly sized metallic components.

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    Materials
  • 287.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hosseini, Vahid
    University West, Department of Engineering Science, Division of Welding Technology.
    Valiente Bermejo, María Asunción
    University West, Department of Engineering Science, Division of Welding Technology.
    Axelsson, Björn
    Alfa Laval Tumba AB, Tumba (SWE).
    Harati, Ebrahim
    University West, Department of Engineering Science, Division of Welding Technology. ITW Welding AB, Partille (SWE).
    Högström, Mats
    University West, Department of Engineering Science, Division of Welding Technology.
    Karlsson, Leif
    University West, Department of Engineering Science, Division of Welding Technology.
    Wire laser metal deposition of 22% Cr duplex stainless steel: as-deposited and heat-treated microstructure and mechanical properties2022In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 57, no 21, p. 9556-9575Article in journal (Refereed)
    Abstract [en]

    Duplex stainless steel (DSS) blocks with dimensions of 150 × 70x30 mm3 were fabricated by Laser Metal Deposition with Wire (LMDw). Implementation of a programmable logic control system and the hot-wire technology provided a stable and consistent process producing high-quality and virtually defect-free deposits. Microstructure and mechanical properties were studied for as-deposited (AD) material and when heat-treated (HT) for 1 h at 1100 °C. The AD microstructure was inhomogeneous with highly ferritic areas with nitrides and austenitic regions with fine secondary austenite occurring in a periodic manner. Heat treatment produced a homogenized microstructure, free from nitrides and fine secondary austenite, with balanced ferrite and austenite fractions. Although some nitrogen was lost during LMDw, heat treatment or reheating by subsequent passes in AD allowed the formation of about 50% austenite. Mechanical properties fulfilled common requirements on strength and toughness in both as-deposited and heat-treated conditions achieving the highest strength in AD condition and best toughness and ductility in HT condition. Epitaxial ferrite growth, giving elongated grains along the build direction, resulted in somewhat higher toughness in both AD and HT conditions when cracks propagated perpendicular to the build direction. It was concluded that high-quality components can be produced by LMDw and that deposits can be used in either AD or HT conditions. The findings of this research provide valuable input for the fabrication of high-performance DSS AM components

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  • 288.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Movahedi, Mojtaba
    Department of Materials Science and Engineering, Sharif University of Technology, Tehran (IRN).
    Consumable pin-friction stir spot welding of Al-Mg-Si alloy via pre-created hole and refilling: Microstructure evolution, defects, and shear/tensile failure load2023In: Proceedings of the Institution of mechanical engineers. Part C, journal of mechanical engineering science, ISSN 0954-4062, E-ISSN 2041-2983, Vol. 237, no 17Article in journal (Refereed)
    Abstract [en]

    Since Al-Mg-Si alloys are widely used in the transportation industry, it is important to produce a sound and robust weld between the sheets of these alloys. The focus of this work is on the tensile-shear and cross-tension strengths of the consumable pin-friction stir spot welds (CP-FSSWs) without an exit-hole between the Al-6061 aluminum sheets. Before welding, a hole was created at the joint region in the base sheets and then, it was filled using a rotating consumable pin. The tensile-shear, cross-tension, and microhardness tests were employed to evaluate the mechanical properties of the spot welds. The results showed that the pre-created hole was entirely filled during the welding process. While a complete bond was formed between the consumable pin and the lateral surface of the hole, there were three distinct regions at the interface of the pin and the bottom of the hole: complete bond, kissing bond, and defects. Enhancement of the tool rotational speed decreased the area of the complete bond in the weld compared to the other regions. A linear relationship existed between the bonding area and weld failure load in the cross-tension test. The proposed relationship approved the impact of the swirly region at the interface of the base sheets on the weld strength. While in the cross-tension test, the weld failure load decreased from ∼2800 to ∼1950 N, it improved from ∼10,500 to ∼12,000 N in the tensile-shear test with enhancement of the tool rotational speed from 700 to 2000 rpm. The hardness measurements demonstrated that there was no common heat affected zone softening after CP-FSSW.  

  • 289.
    Baghdadchi, Amir
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Patel, Vivek
    University West, Department of Engineering Science, Division of Welding Technology.
    Li, Wenya
    State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an, 710072, Shaanxi (CHN).
    Yang, Xiawei
    State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an, 710072, Shaanxi (CHN).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Ductilization and grain refinement of AA7075-T651 alloy via stationary shoulder friction stir processing2023In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 27, p. 5360-5367Article in journal (Refereed)
    Abstract [en]

    This study investigates the microstructural evolution, mechanical properties, and fracture behavior of AA7075-T651 aluminium alloy subjected to stationary shoulder friction stir processing (SSFSP). SSFSP samples were produced at three different rotational speeds in a range of 600–1000 rpm. The results reveal that SSFSP leads to a uniform grain refinement within the Stir Zone (SZ), reducing the grain size to approximately 2–3 μm from the initial 15 μm in the base material (BM) irrespective of the probe rotational speeds. After SSFSP, the elongation increased by over 50 % at the cost of 10 % reduction in the ultimate tensile strength for all samples. It was worth to note that variations in tool rotational speed exhibited minimal influence on the microstructure and mechanical properties, offering wide range of probe rotational speeds. This could be attributed to the use of non-rotating shoulder with prob dominated microstructure in the SZ. Fractographic analysis confirmed the ductile nature of fractures, revealing development of fine dimples due to grain refinement. This work underscores the effectiveness of SSFSP in achieving significant grain refinement followed by drastic increase in ductility, which offers valuable insights for using stationary shoulder at wider range of rotational speed.

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  • 290.
    Bahbou, M. Fouzi
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    A study of the adhesion strength of plasma sprayed coatings2007Doctoral thesis, comprehensive summary (Other academic)
  • 291.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Choquet, Isabelle
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Clement, Uta
    Numerical and experimental study of Ni-particle impact on a ti-surfaceIn: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016Article in journal (Refereed)
  • 292.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Choquet, Isabelle
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Numerical and Experimental Study of Ni-Particle Impact On A Ti-Surface2007In: Proceedings of the International Thermal Spray Conference: May 2007, Beijing, China, ASM International , 2007, p. 219-224Conference paper (Refereed)
  • 293.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    On-Line Measurement of Plasma-Sprayed Ni-Particles during Impact on a Ti-Surface: influence of Surface Oxidation2007In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 16, no 4, p. 506-511Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to analyze the impact of plasma-sprayed Ni5%Al particles on polished and grit-blasted Ti6Al4V samples under oxidized and nonoxidized conditions. For this purpose, measurements of thermal radiation and velocity of individual plasma-sprayed particles were carried out. From the thermal radiation at impact, splat diameter during flattening and temperature evolution during cooling were evaluated. Characteristic parameters related to the quality of contact between the splat and the substrate were retrieved. The flattening speed was introduced to characterize wetting, while the cooling rate was used to characterize solidification. The idea was to get a signature of particle impact for a given surface roughness and oxidation state by identifying parameters which strongly affect the splat behavior. Sieved Ni5%Al powder in a narrow range (+65 −75 μm) was sprayed on four sets of titanium alloy surfaces, consisting of polished and grit-blasted samples, one set had a nonoxidized surface and the other one was oxidized in an oven at 600 °C for two hours. Resulting splats after impact were characterized by scanning electron microscopy, the splats on oxidized surface showed pores in their core and detached fingers at the periphery. The cooling rate and flattening degree significantly increased on the oxidized smooth surface compared to the nonoxidized one. This trend was not found in grit-blasted surfaces, which implies that impact phenomena are different on grit-blasted surfaces than on smooth surfaces thus further work is needed.

  • 294.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    On-Line measurement of plasma-sprayed ni-particles during impact on a ti-surface: influence of surface oxidation2007In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 16, no 6, p. 506-511Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to analyze the impact of plasma-sprayed Ni5%Al particles on polished and grit-blasted Ti6Al4V samples under oxidized and nonoxidized conditions. For this purpose, measurements of thermal radiation and velocity of individual plasma-sprayed particles were carried out. From the thermal radiation at impact, splat diameter during flattening and temperature evolution during cooling were evaluated. Characteristic parameters related to the quality of contact between the splat and the substrate were retrieved. The flattening speed was introduced to characterize wetting, while the cooling rate was used to characterize solidification. The idea was to get a signature of particle impact for a given surface roughness and oxidation state by identifying parameters which strongly affect the splat behavior. Sieved Ni5%Al powder in a narrow range (+65 −75 μm) was sprayed on four sets of titanium alloy surfaces, consisting of polished and grit-blasted samples, one set had a nonoxidized surface and the other one was oxidized in an oven at 600 °C for two hours. Resulting splats after impact were characterized by scanning electron microscopy, the splats on oxidized surface showed pores in their core and detached fingers at the periphery. The cooling rate and flattening degree significantly increased on the oxidized smooth surface compared to the nonoxidized one. This trend was not found in grit-blasted surfaces, which implies that impact phenomena are different on grit-blasted surfaces than on smooth surfaces thus further work is needed.

  • 295.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Relationship between surface topgraphy parameters and adhesion strength for plasma spraying2005In: ITSC 2005: Thermal Spray connects: Explore its surfacing potential!, The Material Information Society , 2005, p. 1027-1031Conference paper (Refereed)
    Abstract [en]

    To achieve sufficient adhesion strength within thermal spraying, the surface to be coated has to be modified. Grit blasting is the most common way to generate a clean and roughened surface. The bonding mechanism between the grit-blasted substrate and the coating is assumed to be due to mechanical anchoring, why an optimal surface roughness is essential. The surface roughness is usually evaluated using Ra which cannot fully characterize the complex nature of the chaotic substrate topography. This study was performed in order to evaluate if Ra can be replaced by other surface characteristic parameters such us R.q, Rpk, Rpv, Rk…with higher correlation to adhesion strength. Average roughness was measured by a perthometer and with white light interferometry to get 3D images of the surface topography. Disc shaped substrate samples of Ti6Al4V (AMS 4928) were grit blasted with aluminium oxide grit and plasma sprayed with a Ni5%Al coating. Adhesion strength was determined according to the ASTM C633 standard. The correlation between a number of different surface-parameters and adhesion strength were evaluated and compared with Ra.

  • 296.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Two-step grit blasting for enhanced adhesion of thermal spray coatings2004In: Surface modification technologies XVIII: proceedings of the eighteenth international conference on surface modification technologies held in Dijon, France November 15-17, 2004, 2004, p. 23-27Conference paper (Refereed)
  • 297.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Barbezat, G.
    Sulzer Metco, Wohlen, Switzerland .
    A parameter study of the Protal® Process to optimise the adhesion of Ni5Al Coatings2004In: Thermal Spray 2004 : Advances in technology and applications: Proceedings of the International Thermal Spray Conference 10-12 May 2004, Osaka, Japan Thermal Spray 2004, 2004, p. 898-902Conference paper (Refereed)
    Abstract [en]

    The Protal process combines surface preparation using a laser and thermal spraying in one production step. The laser preparation is based on a photomechanical reaction induced by the interaction between a laser of high instantaneous power and a polluted surface. The mechanism of bonding and the coating-substrate interface are then changed in comparison with grit blasting resulting in a significantly reduced substrate roughness. This study is aimed at finding the optimal Protal process parameters for the coating adhesion of a Ni5%Al sprayed on Ti6Al4V and IN718 alloys. The parameters investigated are laser beam intensity, the time delay between the laser impact and the spray impact, powder feed rate, substrate roughness and temperature. A test plan including these parameters is analysed by means of a fractional factorial design of experiment method. The adhesions of the coatings are measured using the ASTM C633 standard test. Data are analysed by a multiple linear regression model using a least squares fit. In addition, the coating/substrate interface is examined by optical and electron scanning microscopy (SEM) techniques as well as by Auger electron spectroscopy. Substrate roughness, substrate temperature and laser intensity are all shown to have a negative correlation with adhesion strength within the investigated range. Areas of diffusion are noticed at the coating/substrate interface.

  • 298.
    Bahbou, M. Fouzi
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Nylén, Per
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Wigren, J.
    Volvo Aero, Trollhättan.
    Effect of grit blasting and spraying angle on the adhesion strength of a plasma-sprayed coating2004In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 13, no 4, p. 508-514Article in journal (Refereed)
  • 299.
    Bahtiri, Besnik
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Olsson, Philip
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Automatisering av lågvolymsproduktion: en fallstudie2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A common perception is that it can be difficult to reach a profit margin when automating low volume production. To reach a profit margin, it is required to have a high utilisation rate while still producing profitable products. Vänersborgs Svets & Mekaniska Verkstad manufactures a lot of different low volume products and has recently invested in a robot welding machine. Vänersborgs Svets & Mekaniska Verkstad wants to explore if it will be cost effective to automate four of their low volume products. The robot welding machine has yet to be delivered, hence all calculations will be theoretical.

    The results show that the total cost for the chosen products will be lower if automated, compared to their current method. The cost per part has also been reduced.

    Thus, it is possible for Vänersborgs Svets & Mekaniska Verkstad to increase their cost efficiency by automating the chosen products. The low utilisation rate makes it possible for the company to expand by entering one or more high volume contracts, alternatively entering low volume contracts where the OEM is responsible for the fixture- and programming costs. Vänersborgs Svets & Mekaniska Verkstad should explore the possibility of automating other parts of their products as well.

  • 300.
    Baiamonte, Lidia
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. LIMS, INSTM Reference Laboratory for Engineering of Surface reatments, Department of Chemical Engineering Materials Environment, Sapienza University of Rome, Rome, ITA.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Mulone, Antonio
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg.
    Klement, Uta
    Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Carbide-laden coatings deposited using a hand-held high-velocity air-fuel (HVAF) spray gun2021In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, article id 126725Article in journal (Refereed)
    Abstract [en]

    Driven by sustainability and cost considerations, there is growing interest in power generation utilizing renewable sources, especially biomass and waste. While premature degradation of power plant components due to corrosion is well-known, erosion can be a dominant damage mechanism in plants that use “pure” biomass with less corrosive elements like Cl, K, etc. Circulating fluidized bed (CFB) parts are prone to erosion-driven damage and demand periodic re-protection or replacement. In response to the above, this preliminary study evaluates a selection of complex carbide-based coatings to enhance protection against erosion to prolong service life of boiler components. Recognizing on-site coating requirements of real boiler applications, a specific focus is on evaluating performance of a hand-held high-velocity air-fuel (HVAF) spray gun and compare it with the current state-of-the-art high-velocity oxy-fuel (HVOF) deposition. Coatings developed by the above routes have been characterized with microstructural analyses, and their performance evaluated and ranked in an air-jet erosion rig at various impact angles.

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