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  • Singh, Sukhdeep
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science, SE-41296 Gothenburg, Sweden.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Heat-Affected-Zone Liquation Cracking in Welded Cast Haynes® 282®2019In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 29Article in journal (Refereed)
    Abstract [en]

    Varestraint weldability testing and Gleeble thermomechanical simulation of the newly developed cast form of Haynes® 282® were performed to understand how heat-affected-zone (HAZ) liquation cracking is influenced by different preweld heat treatments. In contrast to common understanding, cracking susceptibility did not improve with a higher degree of homogenization achieved at a higher heat-treatment temperature. Heat treatments with a 4 h dwell time at 1120 °C and 1160 °C exhibited low cracking sensitivity, whereas by increasing the temperature to 1190 °C, the cracking was exacerbated. Nanosecond ion mass spectrometry analysis was done to characterize B segregation at grain boundaries that the 1190 °C heat treatment indicated to be liberated from the dissolution of C–B rich precipitates

  • Ekergård, Boel
    et al.
    University West, Department of Engineering Science, Division of Industrial Engineering and Management, Electrical- and Mechanical Engineering.
    Leijon, Mats
    Uppsala University, Swedish Centre for Renewable Electric Energy Conversion, Department on Engineering Sciences, Uppsala, 751 21, Sweden; Chalmers University of Technology, Department of Electrical Engineering, Gothenburg, 412 96, Sweden .
    Longitudinal end effects in a linear wave power generator2020In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 13, no 2, article id 327Article in journal (Refereed)
    Abstract [en]

    Even though the magnetic circuit of a linear electric machine is very similar to a rotating electric machine, they diverge in one fundamental property. The linear generator is open in both ends, i.e., the magnetic circuit is non-symmetric. This paper investigates and discusses the drawbacks of this non-symmetric design in a linear permanent magnet generator, installed in a wave energy conversion system. A two-dimensional geometry has been utilized for the numerical calculations in a finite element method simulation tool. The results present an increased cogging force and significant core losses in the translator as consequences of the longitudinal ends in the machine. © 2020 by the authors.

  • Dahat, Shubham
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Welding Technology.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology.
    A Methodology to Parameterize Wire + Arc Additive Manufacturing: A Case Study for Wall Quality Analysis2020In: Journal of Manufacturing and Materials Processing, Vol. 4, no 1, article id 14Article in journal (Refereed)
    Abstract [en]

    The objective of this work was the development of a methodology to parametrize wire + arc additive manufacturing (WAAM), aiming dimension repeatability, and tolerances. Parametrization of WAAM is a difficult task, because multiple parameters are involved and parameters are inter-dependent on each other, making overall process complex. An approach to study WAAM would be through operational maps. The choice of current (Im) and travel speed (TS) for the desirable layer width (LW) determines a parametrization that leads to either more material or less material to be removed in post-operations, which is case study chosen for this work. The work development had four stages. First stage, named ‘mock design’, had the objective of visualizing the expected map and reduce further number of experiments. At the second stage, ‘pre-requisite for realistic operational map’, the objective was to determine the operating limits of TS and Im with the chosen consumables and equipment. Within the ‘realistic operational map’ stage, a design for the experiments was applied to cover a parametric area (working envelope) already defined in the previous stage and long and tall walls were additively manufactured. Actual values of LW (external and effective layer width) were measured and an actual operating envelope was reached. According to the geometry-oriented case study, a surface waviness index (SWindex) was defined, determined, and overlapped in the envelope. It was observed that the walls with parameters near the travel speed limits presented higher SWindex. This operational map was further validated (fourth stage) by selecting a target LW and finding corresponding three parametric set (covering the whole range of operational map) to produce walls on which geometry characterization was carried out. After geometry characterization, obtained LW was compared with the target LW (the maximum values were very tied, with deviations from +0.3 to 0.5 mm), with a SWindex deviation at the order of 0.05. Both results evidence high reproductivity of the process, validating the proposed methodology to parametrize WAAM.

  • Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Welding metallurgy and weldability of superalloys2020In: Metals, ISSN 2075-4701, Vol. 10, no 1, article id 143Article in journal (Refereed)
  • Ferreira Magalhães, Ana Catarina
    et al.
    University West, Department of Engineering Science, Division of Production Systems. University West, Department of Engineering Science, Division of Welding Technology.
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Production Systems.
    Bolmsjö, Gunnar
    Linnaeus University, Växjö, Sweden.
    Thermal dissipation effect on temperature-controlled friction stir welding: [Efeito da dissipação térmica inducida durante soldadura por friçcão linear sob controlo de temperatura]2019In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 24, article id e2428Article in journal (Refereed)
    Abstract [en]

    During Friction Stir Welding (FSW) of complex geometries, the thermal dissipation, induced by geometric features or the surrounding environment, may strongly affect the final weld quality. In order to guarantee a consistent weld quality for different conditions, in-process welding parameter adaptation is needed. This paper studies the effect of thermal dissipation, induced by the backing bar thermal conductivity, on the weld temperature and the temperature controller response to it. A new temperature sensor solution, the Tool-Workpiece Thermocouple (TWT) method, was applied to acquire online temperature measurements during welding. An FSW-robot equipped with temperature control, achieved by rotation speed adaptation, was used. AA7075-T6 lap joints were performed with and without temperature control. The cooling rate during welding was register plus macrographs and tensile tests were assessed. The controller demonstrated a fast response promoting the heat input necessary to maintain the set welding temperature. The results demonstrated that temperature control using the TWT method is suitable to achieve higher joint performance and provides a fast setup of optimal parameters for different environments. © 2019, Universidade Federal de Uberlandia. All rights reserved.

  • Ryding, Jennie
    et al.
    University West, Department of Social and Behavioural Studies, Division of Psychology, Pedagogy and Sociology.
    Sorbring, Emma
    University West, Department of Social and Behavioural Studies, Division of Psychology, Pedagogy and Sociology.
    Ny förståelse för forskningsbaserade modeller i familjebehandlande socialt arbete2020In: Barnbladet, ISSN 0349-1994, Vol. XLVI, no 1, p. 12-16Article in journal (Other academic)
    Abstract [sv]

    Evidensbaserad praktik (EBP) har sedan 2000-talet fått en ökad användningsgrad inom människorelaterade yrken, t ex inom verksamheter såsom elevhälsan och socialtjänsten, vars professioner uppmuntras till att arbeta evidensbaserat för att höja graden av kunskapsanvändning och kunskapsutvecklinginom fältet.I den här artikeln kommer vi att beskriva hur förståelsen,inställningen och kunskapen kring EBP och dess relaterade arbetssätt är i stort behov av att problematiseras, då dessa inte sällan bygger på förutfattade meningar och okunskap, vilket i sin tur har resulterat i ett för EBP oförtjänt rykte.

  • Devotta, Ashwin Moris
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Improved finite element modelingfor chip morphology prediction inmachining of C45E steel2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within the manufacturing of metallic components, machining plays an important role and is of vital significance to ensure process reliability. From a cutting tool design perspective, physics-based numerical modeling that can predict chip morphology is highly necessary to design tool macro geometry. The chip morphology describes the chip shape geometry and the chip curl geometry. Improved chip morphology prediction increases process reliability by improved chip breakability and effective chip evacuation.

    To this end, in this work, a platform is developed to compare a numerical model'schip morphology prediction with experimental results. The investigated cuttingprocesses are orthogonal cutting process and nose turning process. Numerical models that simulate the chip formation process are used to predict the chip morphology accompanied by machining experiments. Computed tomography isused to scan the chips obtained from machining experiments evaluating its ability to capture the chip morphology variation. For the nose turning process, chip curl parameters need to be calculated during the cutting process. Kharkevich model is utilized in this regard for calculating the 'chip in process' chip curl parameters. High-speed videography is used to measure the chip side-flow angle during thecutting process experiments enabling comparison with physics-based model predictions.

    With regards to chip shape predictability, the numerical models that simulate the chip formation process are improved by improving the flow stress models and evaluating advanced damage models. The workpiece material, C45E steel, arecharacterized using Gleeble thermo-mechanical simulator. The obtained flow stress is modeled using phenomenological flow stress models. Existing phenomenological flow stress models are modified to improve their accuracy. The fracture initiation strain component of damage models' influence on the prediction of transition from continuous chip to segmented chip is studied. The flow stress models and the damage models are implemented in the numerical models through FORTRAN subroutines. The prediction of continuous to segmented chip transitions are evaluated for varying rake angles and feed rate ata constant cutting velocity.

    The results from the numerical model evaluation platform show that the methodology provides the framework where an advance in numerical models is evaluated reliably from a 'chip morphology prediction capability' viewpoint forthe nose turning process. The numerical modeling results show that the chip curl variation for varying cutting conditions is predicted qualitatively. The flow stress curves obtained through Gleeble thermo-mechanical simulator show dynamic strain aging presence in specific temperature -strain rate ranges. The results of the phenomenological model modification show their ability to incorporate the dynamic strain aging influence. The modified phenomenological model improvesthe accuracy of the numerical models' prediction accuracy. The flow stress models combined with advanced damage model can predict the transition from continuous to segmented chip. Within damage model, the fracture initiation strain component is observed to influence the continuous chip to segmented chip transition and chip segmentation intensity for varying rake angle and feed rate and at a constant cutting velocity.

  • Hanning, Fabian
    et al.
    Chalmers Univ Technol, Dept Ind & Mat Sci, Gothenburg, Sweden.
    Khan, Abdul Khaliq
    Univ Manitoba, Dept Mech Engn, Winnipeg, MB R3T 5V6, Canada.
    Steffenburg-Nordenstroem, Joachim
    GKN Aerosp Sweden AB, S-46138 Trollhattan, Sweden.
    Ojo, Olanrewaju
    Univ Manitoba, Dept Mech Engn, Winnipeg, MB R3T 5V6, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Investigation of the Effect of Short Exposure in the Temperature Range of 750-950 degrees C on the Ductility of Haynes (R) 282 (R) by Advanced Microstructural Characterization2019In: Metals, E-ISSN 2075-4701, Vol. 9, no 12, article id 1357Article in journal (Refereed)
    Abstract [en]

    A Gleeble-based test method has been developed to study the change in the ductility signature of Haynes (R) 282 (R) during isothermal exposure from 5 s to 1800 s. A temperature range of 750 to 950 degrees C has been used to investigate the effect of age-hardening reactions. Microstructural constituents have been analyzed and quantified using scanning and transmission electron microscopy. Carbides present in the material are identified as primary MC-type TiC carbides, Mo-rich M6C secondary carbides, and Cr-rich M23C6 secondary carbides. Gamma prime (gamma’) precipitates are present in all the material conditions with particle sizes ranging from 2.5 nm to 58 nm. Isothermal exposure causes the growth of gamma’ and development of a grain boundary carbide network. A ductility minimum is observed at 800-850 degrees C. The fracture mode is found to be dependent on the stroke rate, where a transition toward intergranular fracture is observed for stroke rates below 0.055 mm/s. Intergranular fracture is characterized by microvoids present on grain facets, while ductility did not change during ongoing age-hardening reactions for intergranularly fractured Haynes (R) 282 (R).

  • Goel, Sneha
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Bourreau, Kévin
    University of Limoges, Specialty Materials, Limoges 87000, France.
    Olsson, Jonas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg 41296, Sweden.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Can Appropriate Thermal Post-Treatment Make Defect Content in as-Built Electron Beam Additively Manufactured Alloy 718 Irrelevant?2020In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, no 3, article id 536Article in journal (Refereed)
    Abstract [en]

    Electron beam melting (EBM) is gaining rapid popularity for production of complex customized parts. For strategic applications involving materials like superalloys (e.g., Alloy 718), post-treatments including hot isostatic pressing (HIPing) to eliminate defects, and solutionizing and aging to achieve the desired phase constitution are often practiced. The present study specifically explores the ability of the combination of the above post-treatments to render the as-built defect content in EBM Alloy 718 irrelevant. Results show that HIPing can reduce defect content from as high as 17% in as-built samples (intentionally generated employing increased processing speeds in this illustrative proof-of-concept study) to <0.3%, with the small amount of remnant defects being mainly associated with oxide inclusions. The subsequent solution and aging treatments are also found to yield virtually identical phase distribution and hardness values in samples with vastly varying as-built defect contents. This can have considerable implications in contributing to minimizing elaborate process optimization efforts as well as slightly enhancing production speeds to promote industrialization of EBM for applications that demand the above post-treatments.

  • Sadeghi, Esmaeil
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants: Part II - Effect of Environment and Outlook2019In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, no 8, p. 1789-1850Article in journal (Refereed)
    Abstract [en]

    High-temperature corrosion of critical components such as water walls and superheater tubes in biomass/waste-fired boilers is a major challenge. A dense and defect-free thermal spray coating has been shown to be promising to achieve a high electrical/thermal efficiency in power plants. The field of thermal spraying and quality of coatings have been progressively evolving; therefore, a critical assessment of our understanding of the efficacy of coatings in increasingly aggressive operating environments of the power plants can be highly educative. The effects of composition and microstructure on high-temperature corrosion behavior of the coatings were discussed in the first part of the review. The present paper that is the second part of the review covers the emerging research field of performance assessment of thermal spray coatings in harsh corrosion-prone environments and provides a comprehensive overview of the underlying high-temperature corrosion mechanisms that lead to the damage of exposed coatings. The application of contemporary analytical methods for better understanding of the behavior of corrosion-resistant coatings is also discussed. A discussion based on an exhaustive review of the literature provides an unbiased commentary on the advanced accomplishments and some outstanding issues in the field that warrant further research. An assessment of the current status of the field, the gaps in the scientific understanding, and the research needs for the expansion of thermal spray coatings for high-temperature corrosion applications is also provided. © 2019, The Author(s).

  • Sreekanth, Suhas
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Hurtig, Kjell
    University West, Department of Engineering Science, Division of Welding Technology.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Ghassemali, Ehsan
    Jönköping University.
    Effect of Direct Energy Deposition Process Parameters on Single-Track Deposits of Alloy 7182020In: Metals, E-ISSN 2075-4701, Vol. 10, no 1, p. 01-16, article id 96Article in journal (Refereed)
    Abstract [en]

    The effect of three important process parameters, namely laser power, scanning speed and laser stand-off distance on the deposit geometry, microstructure and segregation characteristics in direct energy deposited alloy 718 specimens has been studied. Laser power and laser stand-off distance were found to notably affect the width and depth of the deposit, while the scanning speed influenced the deposit height. An increase in specific energy conditions (between 0.5 J/mm2 and 1.0 J/mm2) increased the total area of deposit yielding varied grain morphologies and precipitation behaviors which were comprehensively analyzed. A deposit comprising three distinct zones, namely the top, middle and bottom regions, categorized based on the distinct microstructural features formed on account of variation in local solidification conditions. Nb-rich eutectics preferentially segregated in the top region of the deposit (5.4–9.6% area fraction, Af) which predominantly consisted of an equiaxed grain structure, as compared to the middle (1.5–5.7% Af) and the bottom regions (2.6–4.5% Af), where columnar dendritic morphology was observed. High scan speed was more effective in reducing the area fraction of Nb-rich phases in the top and middle regions of the deposit. The <100> crystallographic direction was observed to be the preferred growth direction of columnar grains while equiaxed grains had a random orientation.

  • Sund, Joakim
    University West, Department of Social and Behavioural Studies, Division for Educational Science and Languages.
    Words and Meaning in Gaming: 'World of Warcraft' and 'Counterstrike Global Offensive'2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Online gaming is a relatively modern phenomenon that is not older than 20 years. Most online players speak English in some form, either by talking or writing. The two games, 'World of Warcraft' and 'Counterstrike' have taken over the gaming-world and the gamers' language has found its way right into the dictionary.

    The aim of the study was to examine how meanings of language change or evolve in the context of online video game playing.

    In this study, two gameplay videos were transcribed and analysed both qualitatively and quantitatively. Gaming words were identified through calculating word frequency in terms of types and tokens, and these identified words were then analysed qualitatively.

    The result contains three categories: Contextual Meaning, New Meaning, and New Words. The concepts of Contextual, New meaning and New Words were compared to dictionary meanings to see whether new meanings were created in the context of the gaming world. Based on the result, the study suggests that game language can influence the overall usage of language in the future.

  • Johansson, Anna
    University West, Department of Social and Behavioural Studies, Division of Social Work and Social Pedagogy.
    Summering av sex års samverkansforskning för främjande av barns och ungas välfärd: Teman och utmaningar2019Report (Other academic)