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  • 1.
    Abrahamsen, Alexandra
    University West, Department of Engineering Science.
    Data Science for In-process Chatter Classification2022Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Milling is one of the most crucial processes in machining. Every industry demands a stable milling process for a smoother finish and material cost reduction. Chatter is a vibrating phenomenon which affects the workpiece's quality, its dimensional accuracy, and tool life. It is required to classify the chatter phenomenon to devise an effective chatter prevention strategy.

    Several classification strategies are being used, including frequency and time-related strategies. Since the chattering phenomenon is a frequency-based phenomenon so a frequency-based feature set can be of vital importance. However, frequency-based strategies have a problem of noise. The noise problem can be addressed by combining frequency and time-domain methods.

    Thus, a hybrid approach based on the frequency and time-based feature set is developed and used in conjunction with k-means-based unsupervised learning to come up with a practical but reliable classifier. The proposed classifier algorithm offers good performance, clearly distinguishing between chatter and stable conditions.

    Based on the chatter classification in this work, it is possible to identify thresholds for chattering detection. It is essential to mention that the thresholds obtained from this work will only be useful for the machine and tool used in the experiments and will not be of use for other machines and need more investigation. 

  • 2.
    Al-Lami, Noor
    University West, Department of Engineering Science.
    Solid-state additive friction-stir manufacturing technology for composite manufacturing2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An experiment study was conducted to locally improve the properties of Al6082-T6 alloy by adding hard particles reinforcement using Friction Stir Processing. Aluminum and its alloys are the most used as a substrate material in the fabrication of Aluminum surface composites because of their lightweight. Thus, aluminum alloy is widely preferred in generating surface composite that is used in sports, marine, aerospace, aircraft, automobile, electronics, railway, etc. Industry requirements ask for good-cost materials with very high properties and light weight. To meet the market requirements, this study has been conducted to investigate the development of the microhardness of Aluminum matrix composites after treating by Friction Stir Processing. From an economic perspective, it is important to enhance the property of the materials by treating the surface instead of the core of the materials. Thus, FSP consid ered in this study as a one of the green fabrication process because it can be done without fume or toxic gases during processing.

    The basic principle of the Friction Stir Process is to use a rotating tool that provides the friction between the tool and the workpiece material producing heating, to produce the wanted plastic deformation. This project aimed to fabricate composites with different reinforcements. The reinforcements used were diamond, cubic Boron Nitride and Graphene. Friction Stir Process was carried out at the tool rotating speed of 1000, 1200 and 1500 rpm and traversing speed of 2, 3 and 5 mm/s. Effects of the number of Friction Stir Process passes were investigated. The samples were all mounted, ground, polished, and analyzed by SEM and optical microscope devices. Microhardness was recorded across the Friction Stir Process region using DU-RAMIN-40 AC1 device with applied load 20, 50, 100 gf.

    It was concluded that a good refinement of the particles size can be achieved in the processed zones for all types of reinforcement. Increasing the number of stirring passes produced well distribution of reinforcement particles and reduced the agglomeration. While increasing rotation speed during processing of graphene reinforcement led to generate more heat, subsequence more agglomeration would be produced. Finally, the results showed that by incorporating diamond reinforcement using single FSP-pass increase the microhardness by about 20% while using double FSP-pass it was found that there was no significant improvement in the microhardness of the composite. A good improvement was also achieved by incorporating the cBN reinforcement where the improvement in the microhardness was also about 20% using single FSP-pass. Increasing rotating speed in FSPed GNP reinforcement leads to generate more heat which leads to more agglomeration or clustering of the reinforcement particles

  • 3.
    Anderberg, Staffan
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Production Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Pejryd, Lars
    3Production Technology Centre, Innovatum AB.
    A survey of metal working companies’ readiness for process planning performance measurements2009In: IEEE International Conference on Industrial Engineering and Engineering Management, IEEM 8-11 sep, 2009, Hong-Kong, 2009, p. 1910-1914Conference paper (Refereed)
    Abstract [en]

    The paper presents an investigation regarding the potential and the readiness for implementing performance indicators and performance measurement systems of the process planning work for metal working companies. The paper is based on a questionnaire survey distributed to process planners in the Swedish metal working industry. The main outcome of the investigation is a foundation for understanding the implementation of performance measures of the process planning work for CNC machining. The survey revealed a few strengths and short comings in the studied companies.

  • 4.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Review of Weldability of Precipitation Hardening Ni- and Fe-Ni-Based Superalloys2018In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications / [ed] Ott, E., Liu, X., Andersson, J., Bi, Z., Bockenstedt, K., Dempster, I., Groh, J., Heck, K., Jablonski, P., Kaplan, M., Nagahama, D. and Sudbrack, C., Springer, 2018, p. 899-916Conference paper (Refereed)
    Abstract [en]

    Fabrication and welding of structural components for the hot section of aero-engines continues to be of high importance to the manufacturing industry of aero-engines. This paper discusses and reviews the literature on hot cracking and strain age cracking, cracking phenomena that can occur during welding or subsequent heat treatment of precipitation hardened Ni- and Fe-Ni-based superalloys. The influence of chemical composition in terms of i.e. hardening elements and impurities, microstructure of base material and weld zone, together with welding processes and corresponding parameters and heat input are discussed and related to the cracking susceptibility of different nickel based superalloys.

  • 5.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Weldability of Ni-based Superalloys2014In: 8th International Symposium on Superalloy 718 and Derivatives: Conference Proceedings / [ed] Ott, E., Banik, A., Andersson, J., Dempster, I., Gabb, T., Groh, J., Heck, K., Helmink, R., Liu, X. & Wusatowska-Sarnek, A., John Wiley & Sons, 2014, p. 249-262Conference paper (Refereed)
  • 6.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Raza, Shahzad
    Department of Materials Science and Engineering, Royal Institute of Technology.
    Eliasson, Anders
    KTH, Department of Materials Science and Engineering, Royal Institute of Technology.
    Surreddi, Kumar Babu
    Chalmers University of Technology, Department of Materials and Manufacturing Technology.
    Solidification of Alloy 718, ATI 718Plus and Waspaloy2014In: 8th International Symposium on Superalloy 718 and Derivatives: Conference Proceedings / [ed] Ott, E., Banik, A., Andersson, J., Dempster, I., Gabb, T., Groh, J., Heck, K., Helmink, R., Liu, X. & Wusatowska-Sarnek, A, John Wiley & Sons, 2014, p. 181-192Conference paper (Refereed)
  • 7.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes. Department of Materials Technology, Volvo Aero Corporation, Trollha¨ttan, Sweden and Chalmers University of Technology, Gothenburg, Sweden.
    Sjöberg, G.
    Department of Materials Technology, Volvo Aero Corporation, Trollha¨ttan, Sweden and Chalmers University of Technology, Gothenburg, Sweden.
    Repair welding of wrought superalloys: Alloy 718, Allvac 718Plus and Waspaloy2012In: Science and Technology of Welding and Joining, ISSN 1362-1718, Vol. 17, no 1, p. 49-59Article in journal (Refereed)
    Abstract [en]

    The ability to weld repair three precipitation hardening superalloys, i.e. Alloy 718, Allvac 718Plus and Waspaloy, with gas tungsten arc welding, is compared in this study. Four different solution heat treatment conditions for each material were examined: Alloy 718 and Allvac 718Plus heat treated at 954uC–1 h, 982uC–1 h, 954uC–15 h and 1020uC–1 h and Waspaloy for 4 h at 996uC, 1010uC, 1040uC and at 1080uC. By metallography, the total number of cracks was evaluated in both the heat affected zone and the fusion zone, which made it possible to consistently rate the repair weldability of these three materials. Alloy 718 was significantly the best one, with Allvac 718Plus slightly better than Waspaloy. As expected, the solution heat treatment conditions only affected the heat affected zone cracking behaviour.

  • 8.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Sjöberg, G.
    Brederholm, A.
    Hänninen, H.
    Solidification Cracking of Alloy Allvac 718Plus and Alloy 718 at Transvarestraint Testing2010In: EPD Congress 2008: Proceedings of Sessions and Symposia Sponsored by the Extraction and Processing Division (EPD) / [ed] Stanley M. Howard, Wiley-Blackwell, 2010, p. 157-169Conference paper (Refereed)
  • 9.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Sjöberg, G.
    Chaturvedi, M.
    Hot Ductility Study of Haynes 282 Superalloy2010In: Superalloy 718 and Derivatives: Proceedings of the 7th International Symposium on Superalloy 718 and Derivatives / [ed] E. A. Ott, J. R. Groh, A. Banik, I. Dempster, T. P. Gabb, R. Helmink, X. Liu, A. Mitchell, G. P. Sjöberg and A. Wusatowska-Sarnek, The Minerals, Metals, and Materials Society, 2010, p. 539-554Conference paper (Refereed)
  • 10.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Sjöberg, G.
    Hatami, S.
    Notch Sensitivity and Intergranular Crack Growth in the Allvac 718Plus Superalloy2007In: XVIII International Symposium on Air Breathing Engines (ISABE): Beijing, China, 2-7 September 2007, 2007, p. n.1293-Conference paper (Refereed)
  • 11.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes. Volvo Aero Corporation, Trollhättan, Sweden och Chalmers University of Technology, Gothenburg, Sweden.
    Sjöberg, G.
    Volvo Aero Corporation, Trollhättan, Sweden och Chalmers University of Technology, Gothenburg, Sweden.
    Hänninen, H.
    Aalto University School of Science and Technology, Espoo, Finland.
    Metallurgical Response of Electron Beam Welded Allvac® 718Plus™2011In: Hot Cracking Phenomena in Welds III / [ed] Lippold, J., Böllinghaus, T. and Cross C. E., Springer Berlin/Heidelberg, 2011, p. 415-428Conference paper (Refereed)
    Abstract [en]

    Electron beam welding of forged Allvac 718Plus superalloy has been carried out without any visible cracks in weld cross-sections. Healed cracks in the heat affected zone were, however, seen in most cross-sections with the healing as well as the cracking believed to be due to the constitutional liquation of the δ-phase. The δ-phase undergoes constitutional liquation in the Heat Affected Zone (HAZ) and consequently decreases the ductility of the material and renders cracks in the HAZ but due to the large amount of eutectic liquid produced at the same time the healing of the opened cracks takes place.

  • 12.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes. Volvo Aero Corporation, Materials Technology Department, Trollhättan, Sweden och Chalmers University of Technology, Department of Materials and Manufacturing Technology, Göteborg,Sweden.
    Sjöberg, G.
    Volvo Aero Corporation, Materials Technology Department, Trollhättan, Sweden och Chalmers University of Technology, Department of Materials and Manufacturing Technology, Göteborg, Sweden.
    Larsson, J.
    Chalmers University of Technology, Department of Materials and Manufacturing Technology, Göteborg,Sweden.
    Investigation of Homogenization and its Influence on the Repair Welding of Cast Allvac 718Plus(®)2010In: Superalloy 718 and Derivatives: Proceedings of the 7th International Symposium on Superalloy 718 and Derivatives / [ed] E. A. Ott, J. R. Groh, A. Banik, I. Dempster, T. P. Gabb, R. Helmink, X. Liu, A. Mitchell, G. P. Sjöberg, and A. Wusatowska-Sarnek, The Minerals, Metals, and Materials Society, 2010, p. 439-454Conference paper (Refereed)
  • 13.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Sjöberg, G.
    Viskari, L.
    Brederholm, A.
    Hänninen, H.
    Knee, C.
    Hot Cracking of Allvac 718Plus, Alloy 718 and Waspaloy at Varestraint Testing2008In: 4th International Symposium on Aerospace Materials and Manufacturing Processes: Advances in Processing and Repair of Aerospace Materials 2008 / [ed] M. Jahazi, M. Elboujdaini and P. Patnaik, Montreal: Canadian Institute of Mining, Metallurgy and Petroleum, 2008, p. 401-413Conference paper (Refereed)
    Abstract [en]

    Varestraint testing together with DSC and SEM-EDX analyses have been performed as means of investigating the hot cracking susceptibility of Allvac 718Plus, alloy 718 and Waspaloy. The solidification sequences in Allvac 718Plus and alloy 718 were very similar to each other starting by an initial solidification of the gamma phase, gamma/MC reaction at around 1260°C and then finally ending the sequence by gamma/Laves eutectic reaction at around 1150°C. Waspaloy had the same solidification sequence, except no Laves phase formation takes place, and solidification started at a somewhat higher temperature as compared to alloy 718 and the solidification sequence ends by a gamma/MC reaction at around 1245°C. The total amount of hot cracking in Waspaloy was shown to be much less than that in alloy 718 and in Allvac 718Plus which is believed to be related to the presence of the Laves eutectic in the latter two alloys with corresponding larger solidification ranges. Hot cracking of 718Plus is slightly less than in 718.

  • 14.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes. Department of Materials Technology, GKN Aerospace Engine Systems, Trollhättan, Sweden och Department of Materials and Manufacturing Technology, Chalmers University of Technology, Gothenburg, Sweden.
    Sjöberg, G.
    Department of Materials Technology, GKN Aerospace Engine Systems, Trollhättan, Sweden och Department of Materials and Manufacturing Technology, Chalmers University of Technology, Gothenburg, Sweden.
    Viskari, L.
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Chaturvedi, M. C.
    Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, MB, Canada.
    Effect of Different Solution Heat Treatments on the Hot Ductility of Superalloys: Part 3 - Waspaloy2013In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847, Vol. 29, no 1, p. 43-53Article in journal (Refereed)
    Abstract [en]

    The susceptibility to heat affected zone cracking of Waspaloy has been investigated in terms of its hot ductility, measured as the reduction of area (RA). Gleeble testing with on-heating as well as on-cooling test cycles was carried out to illuminate the influence of different 4 h solution heat treatments between 996 and 1080°C. A ductility maximum of between 80 and 90%RA was found at 1050–1100°C for all conditions in the on-heating tests. Although the different heat treatment conditions showed similar macrohardness, the particle size and distribution of the γ′ and M23C6 phases differed, which significantly affected the on-heating ductility in the lower temperature test region. The ductile to brittle transition was initiated at 1100°C in the on-heating testing with indications of grain boundary liquation at the higher test temperatures. Ductility recovery, as measured in the on-cooling tests from 1240°C, was very limited with <30%RA for all conditions and test temperatures except for the 1080°C/4 h treatment, which exhibited 60%RA at 980°C.

  • 15.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes. Department of Materials Technology, Volvo Aero Corporation, Trollhättan, Sweden and Department of Materials and Manufacturing Technology, Chalmers University of Technology, Gothenburg, Sweden.
    Sjöberg, G.
    Department of Materials Technology, Volvo Aero Corporation, Trollhättan, Sweden and Department of Materials and Manufacturing Technology, Chalmers University of Technology, Gothenburg, Sweden.
    Viskari, L.
    Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden.
    Chaturvedi, M.C.
    Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, MB, Canada.
    Effect of different solution heat treatments on hot ductility of superalloys: Part 2 – Allvac 718Plus2012In: Materials Science and Technology, ISSN 0267-0836, Vol. 28, no 6, p. 733-741Article in journal (Refereed)
    Abstract [en]

    The hot ductility of Allvac 718Plus for different solution heat treatments (954°C–15 h, 954°C–1 h, 982°C–1 h and 1050°C–3 h+954°C–1 h) has been investigated using Gleeble testing. Substantial variations in the microstructure among the heat treatments affected the Gleeble test hot ductility only to a very limited extent. Constitutional liquation of the NbC phase was found to be the main cause for the poor ductility at high testing temperatures in the on-heating cycle as well as at the lower temperatures on-cooling. Grain boundary δ phase was seen to assist the constitutional liquation of the NbC phase. Based on established evaluation criteria for Gleeble ductility testing, a ranked indicator for weldability is suggested.

  • 16.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes. Department of Materials Technology at Volvo Aero Corporation, Trollhättan, and Chalmers University of Technology, Gothenburg, Sweden.
    Sjöberg, G.
    Department of Materials Technology at Volvo Aero Corporation, Trollhättan, and Chalmers University of Technology, Gothenburg, Sweden.
    Viskari, L.
    Department of Microscopy and Microanalysis at Chalmers University of Technology, 41296 Gothenburg, Sweden.
    Chaturvedi, M.C.
    Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 Canada.
    Effect of solution heat treatments on superalloys: Part 1 – alloy 7182012In: Materials Science and Technology, ISSN 0267-0836, Vol. 28, no 5, p. 609-619Article in journal (Refereed)
    Abstract [en]

    The hot ductility as measured by Gleeble testing of Alloy 718 at four different solution heat treatments (954°C/15 h, 954°C/1 h, 982°C/1 h and 1050°C/3 h+954°C/1 h) has been investigated. It is concluded that constitutional liquation of NbC assisted by δ phase takes place and deteriorates the ductility. Parameters established by analysing the ductility dependence on temperature indicate a reduced weldability of the material in the coarse grain size state (ASTM 3) while indicating an increased weldability when containing a large amount of δ phase due to a grain boundary pinning effect. The accumulation of trace elements during grain growth at the highest temperature is believed to be the cause for the observed reduced on-cooling ductility.

  • 17.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Vikström, Fredrik
    GKN Aerospace Engine Systems.
    Pettersson, Bengt
    GKN Aerospace Engine Systems.
    HIP-Densification of Alloy 718 and ATI 718Plus2014In: 8th International Symposium on Superalloy 718 and Derivatives: Conference Proceedings / [ed] Ott, E., Banik, A., Andersson, J., Dempster, I., Gabb, T., Groh, J., Heck, K., Helmink, R., Liu, X. & Wusatowska-Sarnek, A., John Wiley & Sons, 2014, p. 425-436Conference paper (Refereed)
  • 18.
    Asala, G.
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Ojo, Olanrewaju
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Microstructure Dependence of Dynamic Impact Behaviour of ATI 718plus® Superalloy2018In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications / [ed] Ott, E., Liu, X., Andersson, J., Bi, Z., Bockenstedt, K., Dempster, I., Groh, J., Heck, K., Jablonski, P., Kaplan, M., Nagahama, D. and Sudbrack, C., Springer, 2018, p. 369-378Conference paper (Refereed)
    Abstract [en]

    ATI 718Plus® is a γ′-strengthened nickel-based superalloy developed to substitute the widely used Alloy 718 in aero-engine applications. This newer superalloy is a candidate material for aero-engine turbine structures, with the requirement to withstand impact loading occurring at high strain rates during turbine blade out events. Furthermore, the understanding of the high strain rate response of ATI 718Plus® is important in optimising its machinability during cutting operations. To predict and model the behaviour of ATI 718Plus® during these events and in other dynamic impact applications, proper understanding of the high strain rate behaviour of the alloy is important, but not presently available. Therefore, in this work, the influence of microstructural condition and strain rates on dynamic impact behaviour of ATI 718Plus®, using a modified version of direct impact Hopkinson bar, is investigated. It is observed that the age-hardened alloy exhibits a significantly reduced strain hardening and strain rate hardening capabilities compared to the solution heat treated microstructure. Furthermore, microstructural examination of the deformed samples shows that the formation of adiabatic shear bands, which usually serve as damage nucleation site, is substantially suppressed in the solution heat treated microstructure, while the aged microstructure exhibits high propensity to form localised shear bands.

  • 19.
    Asala, G.
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Khan, A. K.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Mechanical Engineering. University West, Department of Engineering Science, Division of Welding Technology.
    Ojo, O. A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Microstructural Analyses of ATI 718Plus® Produced by Wire-ARC Additive Manufacturing Process2017In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, no 9, p. 4211-4228Article in journal (Refereed)
    Abstract [en]

    A detailed microstructural study of ATI 718Plus superalloy produced by the wire-arc additive manufacturing (WAAM) process was performed through the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe micro-analysis (EPMA), and electron backscatter diffraction (EBSD). Extensive formation of eutectic solidification microconstituents including Laves and MC-type carbide phases, induced by micro-segregation, are observed in the build of the alloy in the as-deposited condition. Notwithstanding the significant segregation of niobium (Nb), which has been reported to promote the formation of the delta-phase in ATI 718Plus, only eta-phase particles are observed in the deposit. Excessive precipitation of eta-phase particles is found to be linked to Laves phase particles that are partially dissolved in the deposit after post-deposition heat treatment (PDHT). The EBSD analysis shows a high textured build in the aOE (c) 100 > directions with only a few misoriented grains at the substrate-deposit boundary and the top of the deposit. Investigation on the hardness of the build of the alloy, in the as-deposited condition, showed a softened zone about 2 mm wide at the deposited metal heat affected zone (DMHAZ), which has not been previously reported and potentially damaging to the mechanical properties. An extensive analysis with the use of both microstructural characterization tools and theoretical calculations shows that the DMHAZ has the lowest volume fraction of strengthening precipitates (gamma’ and gamma aEuro(3)) in terms of their number density, which therefore induces the observed softness. Delayed re-precipitation kinetics and the extent of the precipitation of gamma’ and gamma aEuro(3) in the DMHAZ which is related to the diffusion of segregated solute elements from the interdendritic regions are attributed to this phenomenon. The microstructural analyses discussed in this work are vital to adequate understanding of properties of ATI 718Plus produced by the additive manufacturing process technique.

  • 20.
    Asala, Gbenga
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Ojo, Olanrewaj A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Hot corrosion behaviour of wire-arc additive manufactured Ni-based superalloy ATI 718Plus®2019In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 158, article id 108086Article in journal (Refereed)
    Abstract [en]

    The hot corrosion behaviour of wire-arc additive manufactured and wrought ATI 718Plus® are studied. ATI 718Plus® produced by the additive manufacturing process, in the as-processed condition, exhibits a significantly lower hot corrosion resistance in comparison to the wrought alloy. Analytical electron microscopy and spectroscopy techniques, with corroboration by thermodynamic calculations, are used to identify the underlying cause of the poor hot corrosion resistance. Based on the understanding accrued from the analyses, post-processing heat treatments are used to improve the hot corrosion resistance, which is valuably pertinent to the application of ATI 718Plus® produced by additive manufacturing in hot corrosive environments. © 2019 Elsevier Ltd

  • 21.
    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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  • 22.
    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
  • 23.
    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
  • 24.
    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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  • 25.
    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)
  • 26.
    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)
  • 27.
    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)
  • 28.
    Bandyopadhyay, Robi
    University West, Department of Technology.
    Modelling of the flame spraying process2003Report (Other (popular science, discussion, etc.))
  • 29.
    Barick, Prasenjit
    et al.
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Chakravarty, Dibyendu
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Saha, Bhaskar Prasad
    International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Nitra, Rahul
    Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721302 West Bengal, India.
    Joshi, Shrikant
    University West, Department of Engineering Science, Research Enviroment Production Technology West. International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur Post, Hyderabad, 500005 Telangana, India.
    Effect of pressure and temperature on densification, microstructure and mechanical properties of spark plasma sintered silicon carbide processed with β-silicon carbide nanopowder and sintering additives2016In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 42, no 3, p. 3836-3848Article in journal (Refereed)
    Abstract [en]

    The effects of applied pressure and temperature during spark plasma sintering (SPS) of additive-containing nanocrystalline silicon carbide on its densification, microstructure, and mechanical properties have been investigated. Both relative density and grain size are found to increase with temperature. Furthermore, with increase in pressure at constant temperature, the relative density improves significantly, whereas the grain size decreases. Reasonably high relative density (~96%) is achieved on carrying out SPS at 1300 °C under applied pressure of 75 MPa for 5 min, with a maximum of ~97.7% at 1500 °C under 50 MPa for 5 min. TEM studies have shown the presence of an amorphous phase at grain boundaries and triple points, which confirms the formation of liquid phase during sintering and its significant contribution to densification of SiC at relatively lower temperatures (≤1400 °C). The relative density decreases on raising the SPS temperature beyond 1500 °C, probably due to pores caused by vaporization of the liquid phase. Whereas β-SiC is observed in the microstructures for SPS carried out at temperatures ≤1500 °C, α-SiC evolves and its volume fraction increases with further increase in SPS temperatures. Both hardness and Young׳s modulus increase with increase in relative density, whereas indentation fracture toughness appears to be higher in case of two-phase microstructure containing α and β-SiC.

  • 30.
    Bates, William P.
    et al.
    Department of Engineering Science, University West, Trollhättan (SWE).
    Patel, Vivek
    University West, Department of Engineering Science, Division of Welding Technology.
    Rana, Harikrishna
    Department of Engineering, University of Palermo, Palermo (ITA).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Production Systems. Friction Welding Process Section, TWI Ltd., Cambridge (GBR).
    Igestrand, Mattias
    University West, Department of Engineering Science, Division of Welding Technology.
    Fratini, Livan
    Department of Engineering, University of Palermo, Palermo (ITA).
    Properties Augmentation of Cast Hypereutectic Al-Si Alloy Through Friction Stir Processing2022In: Metals and Materials International, ISSN 1598-9623, E-ISSN 2005-4149Article in journal (Refereed)
    Abstract [en]

    The present endeavour is to augment mechanical attributes via friction stir processing (FSP) in hypereutectic aluminium-silicon castings by the means of microstructural modifications and defects reduction. Wherein, the study proceeds with mainly two approaches namely, alteration in tool revolution (TR) and the number of FSP passes. The prepared specimens were evaluated investigating volume fraction of porosities, microstructural characterizations and microhardness. Therefrom, the specimen with highest number of passes delivered most uniform properties resulting from the reduction in casting porosities and refined silicon particle uniform distribution throughout friction stir processed zone. This endeavour may be considered as a footstep towards more industrial readied material transformation.

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    Springer
  • 31.
    Beno, Thomas
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Isaksson, Marina
    Pejryd, Lars
    University West, Department of Engineering Science, Division of Production Engineering.
    Investigation of Machining Greek Ascaloy with Minimal Quantity Lubrication Sustainable/Cleaner Manufacturing2008In: LCE 2008: 15th CIRP International Conference on Life Cycle Engineering: Conference Proceedings, Sidney, 17-19 March, 2008Conference paper (Refereed)
  • 32.
    Beno, Tomas
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Isaksson, Marina
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Pejryd, Lars
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Investigation of Minimal Quantity Cooling Lubrication in Turning of Inconel 7182007In: Proceedings of the 3rd International Conference on Tribology in Manufacturing Processes: ICTMP 2007, Yokohama, Japan 24-26 September, 2007, p. 281-286Conference paper (Other academic)
  • 33.
    Bolelli, G.
    et al.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Berger, L. -M
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, D-01277 Dresden, Germany.
    Börner, T.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Koivuluoto, H.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, FI-33720 Tampere, Finland.
    Lusvarghi, L.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Lyphout, Christophe
    University West, Department of Engineering Science, Division of Production Engineering.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Production Engineering.
    Matikainen, V.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, FI-33720 Tampere, Finland.
    Nylén, Per
    University West, Department of Engineering Science, Division of Production Engineering.
    Sassatelli, P.
    University of Modena and Reggio Emilia, Dipartimento di Ingegneria “Enzo Ferrari”, Via Pietro Vivarelli 10/1, I-41125 Modena (MO), Italy.
    Trache, R.
    Fraunhofer-Institut für Werkstoff- und Strahltechnik (IWS), Winterbergstr. 28, D-01277 Dresden, Germany.
    Vuoristo, P.
    Tampere University of Technology, Department of Materials Science, Korkeakoulunkatu 6, FI-33720 Tampere, Finland.
    Tribology of HVOF- and HVAF-sprayed WC-10Co4Cr hardmetal coatings: A comparative assessment2015In: Surface and Coatings Technology, ISSN 0257-8972, Vol. 265, p. 125-144Article in journal (Refereed)
    Abstract [en]

    his paper provides a comprehensive assessment of the sliding and abrasive wear behaviour of WC–10Co4Cr hardmetal coatings, representative of the existing state-of-the-art. A commercial feedstock powder with two different particle size distributions was sprayed onto carbon steel substrates using two HVOF and two HVAF spray processes.Mild wear rates of < 10-7 mm3/(Nm) and friction coefficients of ≈ 0.5 were obtained for all samples in ball-on-disk sliding wear tests at room temperature against Al2O3 counterparts. WC–10Co4Cr coatings definitely outperform a reference electrolytic hard chromium coating under these test conditions. Their wear mechanisms include extrusion and removal of the binder matrix, with the formation of a wavy surface morphology, and brittle cracking. The balance of such phenomena is closely related to intra-lamellar features, and rather independent of those properties (e.g. indentation fracture toughness, elastic modulus) which mainly reflect large-scale inter-lamellar cohesion, as quantitatively confirmed by a principal component analysis. Intra-lamellar dissolution of WC into the matrix indeed increases the incidence of brittle cracking, resulting in slightly higher wear rates. At 400 °C, some of the hardmetal coatings fail because of the superposition between tensile residual stresses and thermal expansion mismatch stresses (due to the difference between the thermal expansion coefficients of the steel substrate and of the hardmetal coating). Those which do not fail, on account of lower residual stresses, exhibit higher wear rates than at room temperature, due to oxidation of the WC grains.The resistance of the coatings against abrasive wear, assessed by dry sand–rubber wheel testing, is related to inter-lamellar cohesion, as proven by a principal component analysis of the collected dataset. Therefore, coatings deposited from coarse feedstock powders suffer higher wear loss than those obtained from fine powders, as brittle inter-lamellar detachment is caused by their weaker interparticle cohesion, witnessed by their systematically lower fracture toughness as well.

  • 34.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Surface crack detection in welds using thermography2013In: NDT & E international, ISSN 0963-8695, E-ISSN 1879-1174, Vol. 57, p. 69-73Article in journal (Refereed)
    Abstract [en]

    Thermography is today used within non-destructive testing for detecting several different types of defects. The possibility for using thermography for detecting surface cracks in welded metal plates has here been investigated. During testing the weld is illuminated using a high power infrared light source. Due to surface cracks acting like black bodies, they will absorb more energy than the surrounding metal and can be identified as a warmer area when imaged using an infrared camera. Notches as well as real longitudinal cold cracks in a weld are investigated using the presented method. The results show that thermography is promising as a method for detection cracks open to the surface.

  • 35.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Production Systems.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production Systems.
    Analysis algorithm for surface crack detection by thermography with UV light excitation2016In: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Kaczmarek, M. & Bujnowski, A., Gdańsk, Poland: Publishing Gdańsk University of Technology , 2016, p. 160-165Conference paper (Refereed)
    Abstract [en]

    Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.

  • 36.
    Charles, Corinne
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Modelling Microstructure Evolution in Weld Deposited Titanium2007In: NAFEMS Contact Nordic Countries, 2007, NAFEMS Nordic seminar; 4 (Oslo): 2007.03.20-21, 2007Conference paper (Other academic)
  • 37.
    Charles, Corinne
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Järvstråt, Niklas
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Development of a Microstructure Model for Metal Deposition of Titanium Alloy Ti-6Al-4V2007In: Ti-2007 : science and technology : proceedings of the 11th World Conference on Titanium (JIMIC 5): held at Kyoto International Conference Center, Kyoto, Japan, 3 - 7 June 2007, 2007, p. 1201-1205Conference paper (Refereed)
  • 38.
    Charles, Corinne
    et al.
    University West, Department of Engineering Science, Division of Production Engineering.
    Järvstråt, Niklas
    University West, Department of Engineering Science, Division of Production Engineering.
    Modelling Ti-6Al-4V microstructure by evolution laws implemented as finite element subroutines:: Application to TIG metal deposition2008In: 8 th International Conference on Trends in welding research,: Pine Mountain, Georgia, June 2-6, 2008Conference paper (Other academic)
  • 39.
    Choquet, Isabelle
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Björklund, Stefan
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Johansson, Jimmy
    Volvo Aero Corporation, Trollhättan.
    Wigren, Jan
    Volvo Aero Corporation, Trollhättan.
    Clogging and lump formation during atmospheric plasma spraying with powder injection downstream the plasma gun2007In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 16, no 4, p. 512-523Article in journal (Refereed)
    Abstract [en]

    This study aimed to numerically and experimentally investigate lump formation during atmospheric plasma spraying with powder injection downstream the plasma gun exit. A first set of investigations was focused on the location and orientation of the powder port injector. It turned out impossible to keep the coating quality while avoiding lumps by simply moving the powder injector. A new geometry of the powder port ring holder was designed and optimized to prevent nozzle clogging, and lump formation using a gas screen. This solution was successfully tested for applications with Ni-5wt.%Al and ZrO2-7wt.%Y2O3 powders used in production. The possible secondary effect of plasma jet shrouding by the gas screen, and its consequence on powder particles prior to impact was also studied.

  • 40.
    Cruz-Crespo, Amado
    et al.
    Universidad Central "Marta Abreu" de Las Villas, Universidade Federal de Uberlandia.
    Gonzalez, Lorenzo Perdomo
    Anim Hlth & Vet Labs Agcy, VLA Lasswade Vet Labs Agcy Lasswade, King Abdulaziz University.
    Rafael, Quintana
    Universidad Central "Marta Abreu" de Las Villas.
    Scotti, Americo
    University West, Department of Engineering Science, Division of Welding Technology. Universidade Federal de Uberlandia University West - Sweden Fed Univ Uberlandia UFU.
    Flux for Hardfacing by Submerged Arc Welding from Ferrochrome-manganese and Slag from the Simultaneous Reduction of Chromite and Pyrolusite2019In: Soldagem & Inspeção, ISSN 0104-9224, E-ISSN 1980-6973, Vol. 24, article id e2424Article in journal (Refereed)
    Abstract [en]

    The obtaining of a flux for hardfacing by Submerged Arc Welding (SAW), using ferrochrome-manganese and slag obtained from the simultaneous carbothermal reduction of chromite and pyrolusite is addressed. The ferrochrome-manganese and the slag were obtained, conceiving that both products satisfy the requirements of the components (alloy system and matrix) of an agglomerated flux for hardfacing. The fusion-reduction process to obtain the alloy and the slag was carried out in a direct current electric arc furnace. The pouring was carried out into water to facilitate the separation and grinding of the cast products. An experimental flux was manufactured, using the obtained alloy and slag. Deposits were obtained by SAW, which were characterized in terms of: chemical composition, microstructure and hardness. It was concluded that the flux obtained from ferrochrome-manganese and slag from the simultaneous carbothermal reduction of chromite and pyrolusite, allows to deposit an appropriate metal for work under abrasion conditions, characterized by significant carbon and chromium contents and a martensitic microstructure predominantly, with hardness of 63 HRc.

  • 41. Davies, P.
    et al.
    Pederson, Robert
    University West, Department of Engineering Science, Division of Welding Technology. University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Institute of Structural Materials, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom.
    Coleman, M.
    Institute of Structural Materials, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom.
    Birosca, S.
    Institute of Structural Materials, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea SA1 8EN, United Kingdom.
    The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air2016In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 117, p. 51-67Article in journal (Refereed)
    Abstract [en]

    Ductility regression is the main concern in using Ti-834 titanium alloy at temperatures above 500 °C for aerospace applications. The reduction of ductility in titanium alloys at high temperatures is strongly correlated to the exposure time. In the current study the effect of prolonged exposure at 500 °C on the tensile ductility of two differently processed Ti-834 alloys was investigated. In order to simulate actual Ti-834 processing routes, forged and centrifugally cast materials were used. The tensile tests were conducted on various specimens exposed at 500 °C for 100, 200 and 500 h to observe microstructure feature changes. Moreover, the effect of microstructure, microtexture, α-case, α2 and silicide precipitate coarsening during high temperature exposure was studied thoroughly. The cast alloy was found to have a minimum ductility and failed at 1.8% strain after exposure at 500 °C/500 h when the α-case layer was retained during testing, whilst, the ductility of the forged alloy was unaffected. The effects of individual microstructural parameters on the ductility regression in Ti-834 alloy were quantified. The results showed that 7.1% strain differences between the cast and forged alloy are related to microstructural variations including; morphology, lath widths, grain size and shape, grain orientations and microtexture. A total of 9.6% strain loss was observed in centrifugally cast Ti-834 after aging at 500°C/500 h and quantified as follow; 3.6% due to α-case formation during high temperature exposure, 0.2% due to α2-precipitates coarsening, 4.4% due to further silicide formation and coarsening, 1.4% due to additional microstructure changes during high temperature exposure. Furthermore, silicide coarsening on α/β phase boundaries caused large void formation around the precipitates. A theoretical model supported by experimental observations for silicide precipitation in fully colony and duplex microstructures was established. The element partitioning during exposure caused Al and Ti depletion in the vicinity of the β phase in the lamellae, i.e., αs area. This resulted in lowering the strength of the alloy and facilitated the formation of Ti3(SiZr)2 precipitates. The Al depletion and nano-scale partitioning observed at the αs/β boundaries resulted in easy crack initiation and promoted propagation in the centrifugally cast colony microstructure and reduced the basal slip τcrss. Furthermore, silicides were not formed in αp (high Al, Ti and low Zr areas) in the forged duplex microstructure that promoted superior mechanical performance and ductility over the cast alloy.

    Graphical abstract

  • 42.
    Draxler, Joar
    et al.
    Luleå University of Technology, Luleå, 97187, Sweden.
    Edberg, Jonas
    Luleå University of Technology, Luleå, 97187, Sweden.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Lindgren, Lars -Erik
    Luleå University of Technology, Luleå, 97187, Sweden.
    Modeling and simulation of weld solidification cracking part I: A pore-based crack criterion2019In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 5, p. 1489-1502Article in journal (Refereed)
    Abstract [en]

    Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair and, if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model for computing the pressure and the thickness of the grain boundary liquid film, which are required to evaluate the crack criterion in paper 1. The third and final paper describes the application of the model to Varestraint tests of alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown. © 2019, The Author(s).

  • 43.
    Draxler, Joar
    et al.
    Luleå University of Technology, Luleå, 97187, Sweden.
    Edberg, Jonas
    Luleå University of Technology, Luleå, 97187, Sweden.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Lindgren, Lars -Erik
    Luleå University of Technology, Luleå, 97187, Sweden.
    Modeling and simulation of weld solidification cracking part II: A model for estimation of grain boundary liquid pressure in a columnar dendritic microstructure2019In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 5, p. 1503-1519Article in journal (Refereed)
    Abstract [en]

    Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair, and if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model for computing the pressure and the thickness of the grain boundary liquid film, which are required to evaluate the crack criterion in paper 1. The third and final paper describes the application of the model to Varestraint tests of Alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown. © 2019, The Author(s).

  • 44.
    Draxler, Joar
    et al.
    Luleå University of Technology, Luleå, 97187, Sweden.
    Edberg, Jonas
    Luleå University of Technology, Luleå, 97187, Sweden.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Lindgren, Lars-Erik
    Luleå University of Technology, Luleå, 97187, Sweden.
    Modeling and simulation of weld solidification cracking part III: Simulation of solidification cracking in Varestraint tests of alloy 7182019In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 63, no 6, p. 1883-1901Article in journal (Refereed)
    Abstract [en]

    Several advanced alloy systems are susceptible to weld solidification cracking. One example is nickel-based superalloys, which are commonly used in critical applications such as aerospace engines and nuclear power plants. Weld solidification cracking is often expensive to repair, and if not repaired, can lead to catastrophic failure. This study, presented in three papers, presents an approach for simulating weld solidification cracking applicable to large-scale components. The results from finite element simulation of welding are post-processed and combined with models of metallurgy, as well as the behavior of the liquid film between the grain boundaries, in order to estimate the risk of crack initiation. The first paper in this study describes the crack criterion for crack initiation in a grain boundary liquid film. The second paper describes the model required to compute the pressure and thickness of the liquid film required in the crack criterion. The third and final paper describes the application of the model to Varestraint tests of alloy 718. The derived model can fairly well predict crack locations, crack orientations, and crack widths for the Varestraint tests. The importance of liquid permeability and strain localization for the predicted crack susceptibility in Varestraint tests is shown. © 2019, The Author(s).

  • 45.
    Draxler, Joar
    et al.
    University West, Department of Engineering Science, Division of Welding Technology.
    Åkerström, P.
    Lulea University of Technology, 97187 Luleå, Sweden.
    Edberg, J.
    Lulea University of Technology, 97187 Luleå, Sweden.
    Lindgren, L. -E
    Lulea University of Technology, 97187 Luleå, Sweden.
    Singh, S.
    Chalmers University of Technology, 41296 Goteborg, Sweden .
    Raza, Tahira
    University West, Department of Engineering Science, Division of Welding Technology.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    A numerical model for simulating the effect of strain rate on eutectic band thickness2020In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 64, p. 1635-1658Article in journal (Refereed)
    Abstract [en]

    Large tensile strains acting on the solidifying weld metal can cause the formation of eutectic bands along grain boundaries. These eutectic bands can lead to severe liquation in the partially melted zone of a subsequent overlapping weld. This can increase the risk of heat-affected zone liquation cracking. In this paper, we present a solidification model for modeling eutectic bands. The model is based on solute convection in grain boundary liquid films induced by tensile strains. The proposed model was used to study the influence of strain rate on the thickness of eutectic bands in Alloy 718. It was found that when the magnitude of the strain rate is 10 times larger than that of the solidification rate, the calculated eutectic band thickness is about 200 to 500% larger (depending on the solidification rate) as compared to when the strain rate is zero. In the paper, we also discuss how eutectic bands may form from hot cracks. © 2020, The Author(s).

  • 46.
    Ericsson, Mikael
    et al.
    University West, Department of Technology, Mathematics and Computer Science, Division for Mechanical Engineering.
    Bolmsjö, Gunnar
    University West, Department of Engineering Science, Division of Automation Systems.
    Nylén, Per
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Three-dimensional simulation of robot path and heat transfer of a TIG-welded part with complex geometry2002In: 11th International Conferences on Computer Technology in Welding: Colombus, Ohio December 6-7, 2001, 2002, p. 309-316Conference paper (Other academic)
    Abstract [en]

    The application of commercial software (OLP) packages for robot simulation, and programming, use interactive computer graphics, provide powerful tools for creating welding paths off-line. By the use of such software, problems of robot reach, accessibility, collision and timing can be eliminated during the planning stage. This paper describes how such software can be integrated with a numerical model that predicts temperature-time histories in the solid material. The objective of this integration is to develop a tool for the engineer where robot trajectories and process parameters can be optimized on parts with complex geometry. Such a tool would decrease the number of weld trials, increase productivity and reduce costs. Assumptions and principles behind the modeling techniques are presented together with experimental evaluation of the correlation between modeled and measured temperatures.

  • 47.
    Eriksson, Erik
    et al.
    Department of Physics, Chalmers University of Technology, Gothenburg (SWE).
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Hörnqvist Colliander, M.
    Department of Physics, Chalmers University of Technology, Gothenburg (SWE).
    The Effect of Grain Boundary Carbides on Dynamic Recrystallization During Hot Compression of Ni-Based Superalloy Haynes 282 TM2021In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940Article in journal (Refereed)
    Abstract [en]

    In alloys where carbides are the main grain boundary phase, the role of carbides during hot working is not known. Here, we address the effect of grain boundary carbides on the dynamic recrystallization during hot compression of Ni-base superalloy Haynes 282. When excluding variations from experimental factors neither stress evolution nor final microstructure indicated that carbides exerted a significant influence on the dynamic recrystallization. The carbide solvus temperature is not a critical limit during thermomechanical processes.

    Download full text (pdf)
    Springer
  • 48.
    Evervall, Jesper
    University West, Department of Engineering Science.
    Friction stir welding of dissimilar aluminium alloys (AA5083-AA6082): Microstructure and mechanical properties evaluation2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To meet the demand for building light construction in moving vehicles or bridge construction, it is necessary to reduce the material usage and, or, material weight to reduce the environmental footprint, resulting in lower weight. A solution is to use Aluminium (Al) due to its excellent strength to weight ratio and properties such as high corrosion resistance. In construction, different classes of Al are used based on their variations of advantages. A challenge with this type of construction is when the Al classes are required to be welded together. To weld them together by fusion welding is complex compared to the welding of Steel. However, welding Al by Friction Stir Welding (FSW) it is possible to achieve a defect-free weld. Defects such as voids and cracks can be avoided. Both welding of non-heat treatable or heat treatable Al materials can be done by using FSW because the Al will not be melted but stay in the solid state.

    The main aim was to achieve a defect-free weld of the dissimilar heat-treatable Al AA6082 and non-heat-treatable AA5083 by Friction Stir Welding (FSW), which is a more challenging than welding the same Al grades together. In addition, also get a better understanding of how the material placement effect the material mixing, hardness and how process parameters effect the weld quality and mixing. By altering the parameters rotational speed (1000-1300 rpm), downward force (3,5 kN-5,5 kN), welding speed (2,5 - 5 mm/s), and tool offset into Advancing Side (AS) (0- 2 mm). 

    The samples were produced at PTC (Production Technology Centre), Trollhättan with an ABB six-axis robot with an FSW module. The tool had a convex shoulder (12 mm) with two scrolls and a crown pin (5 mm). Slower rotational speed (1200 rpm) and higher downward force (> 5 kN) gave the result of a defect-free weld with AA6082 placed at AS. The material placement strongly effects the material flow by the domination of AS material in the Thermo-Mechanically Affected Zone (TMAZ)-AS and Stir Zone (SZ) for both material placement, which was identified by the Vickers hardness test and Energy Dispersive Spectroscopy (EDS) analysis. Further, the weld was visible in the TMAZ/SZ after etching with Flick's reagent for 3 min.

    Lighter areas were dominated by AA6082 and darker areas were dominated by AA5083. A higher hardness was seen in the areas dominated by AA5083 compared to the areas dominated by AA6082. The AA5083 needed a higher heat input to be welded compared to AA6082. Therefore, when AA5083 was placed at AS, it resulted in more problems with insufficient material mix and/or lack of heat input. The offsetting of the tool into AA5083 resulted in tunnel defects. To get a defect-free weld with AA5083 at AS, a larger shoulder diameter is recommended to increase the material mix and heat input.

  • 49.
    Fahlström, Karl
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Laser welding of boron steels for light-weight vehicle applications2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Laser beam welding has gained a significant interest during the last two decades. The suitability of the process for high volume production has the possibility to give a strong advantage compared to several other welding methods. However, it is important to have the process in full control since various quality issues may otherwise occur. During laser welding of boron steels quality issues such as imperfections, changes in local and global geometry as well as strength reduction can occur. The aspects that need to be considered are strongly depending on alloy content, process parameters etc. These problems that can occur could be fatal for the construction and the lowest level of occurrence is wanted, independent of industry.

    The focus of this study has been to investigate the properties of laser welded boron steel. The study includes laser welding of boron alloyed steels with strengths of 1500 MPa and a recently introduced 1900 MPa grade. Focus has been to investigate weldability and the occurrence of cracks, porosity and strength reducing microstructure that can occur during laser welding, as well as distortion studies for tolerances in geometry. The results show that both conventional and 1900 MPa boron alloyed steel are suitable for laser welding.

    Due to the martensitic structure of welds the material tends to behave brittle. Cracking and porosity do not seem to be an issue limiting the use of these steels. For tolerances in geometry for larger structures tests has been done simulating laser welding of A-pillars and B-pillars. Measurements have been done with Vernier caliper as well as a more advanced optical method capturing the movements during the welding sequence. Results from the tests done on Ushaped beams indicates that depending on the geometry of the structure and heat input distortions can be controlled to give distortions from 1 to 8 mm, at a welding length of 700 mm. This means that important geometry points can be distorted several millimeters if the laser welding process not is controlled.

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    fulltext
  • 50.
    Fahlström, Karl
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. Swerea KIMAB, Joining Technology, Kista, Sweden .
    Andersson, Oscar
    Volvo Cars, Torslanda; XPRES, KTH Royal Institute of Technology.
    Todal, Urban
    Volvo Cars, Torslanda.
    Melander, Arne
    Swerea KIMAB, Joining Technology, Kista; XPRES, KTH Royal Institute of Technology, Stockholm.
    Minimization of distortions during laser welding of ultra-high strength steel2014In: ICALEO 2014 Congress proceedings, 2014, p. 1-10Conference paper (Refereed)
    Abstract [en]

    Ultra high strength steels are frequently used within the automotive industry for several components. Welding of these components is traditionally done by resistance spot welding, but to get further productivity and increased strength, laser welding has been introduced in the past decades. Fusion welding is known to cause distortions due to built-in stresses in the material. The distortions result in geometrical issues during assembly which become the origin of low joint quality due to gaps and misfits.

    U-beam structures of boron steel simulating B-pillars have been welded with laser along the flanges. Welding parameters and clamping have been varied to create different welding sequences and heat input generating a range of distortion levels. The distortions have been recorded dynamically with an optical measurement system during welding. In addition, final distortions have been measured by a digital Vernier caliper. The combined measurements give the possibility to evaluate development, occurrence and magnitude of distortions with high accuracy. Furthermore, section cuts have been analyzed to assess joint geometry and metallurgy.

    The results shows that final distortions appear in the range of 0-8 mm. Distortions occur mainly transversely and vertically along the profile. Variations in heat input show clear correlation with the magnitude of distortions and level of joint quality. A higher heat input in general generates a higher level of distortion with the same clamping conditions. Section cuts show that weld width and penetration are significantly affected by welding heat input.

    The present study identifies parameters which significantly influence the magnitude and distribution of distortions. Also, effective measures to minimize distortions and maintain or improve joint quality have been proposed.

    Finally, transient FE simulations have been presented which show the behavior of the profiles during the welding and unclamping process.

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