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  • 1.
    Abou Nada, Fahed
    et al.
    Lund University, Department of Physics, Division of Combustion Physics, Box 118, Lund, Swede.
    Lantz, Andreas
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Larfeldt, Jenny
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Markocsan, Nicolaie
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Alden, Marcus
    Lund University, Department of Physics, Division of Combustion Physics, Box 118, Lund, Swede.
    Richter, Mattias
    Lund University, Department of Physics, Division of Combustion Physics, Box 118, Lund, Swede.
    Remote temperature sensing on and beneath atmospheric plasma sprayed thermal barrier coatings using thermographic phosphors2016In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 302, p. 359-367Article in journal (Refereed)
    Abstract [en]

    Investigations on remote temperature sensing of yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) at the surface and at the bond-coat/top-coat interface were carried out. Using Y2O3:Eu thermographic phosphor as an embedded temperature sensing layer, sub-surface temperature probing through 300 mu m of atmospheric plasma sprayed YSZ is demonstrated. The Y2O3:Eu thermographic phosphor displays a temperature sensitivity ranging between 400 degrees C up to a maximum of 900 degrees C when utilizing the luminescence originating from the 611 nm emission band. Dysprosium stabilized zirconia (10 wt.% DySZ), a TBC material, is also investigated and established as a temperature sensor from 400 degrees C up to a temperature of 1000 degrees C using both the intensity decay time and emission intensity ratio methods. In addition, the luminescence of presumed optically inactive YSZ materials was spectroscopically investigated in terms of optical interferences caused by impurities. A validation temperature probing measurement through 300 mu m of YSZ top-coat was successfully performed in a SGT-800 Siemens burner running at six different operating conditions in an atmospheric combustion rig. (C) 2016 Elsevier B.V. All rights reserved.

  • 2.
    Adli, E.
    et al.
    University of Oslo, Oslo, Norway.
    Gjersdal, H.
    University of Oslo, Oslo, Norway.
    Røhne, O.M.
    University of Oslo, Oslo, Norway.
    Dorholt, O.
    University of Oslo, Oslo, Norway.
    Bang, D.M.
    University of Oslo, Oslo, Norway.
    Thomas, D,
    ESS ERIC, Lund, Sweden.
    Shea, T.
    ESS ERIC, Lund, Sweden.
    Andersson, R.
    ESS ERIC, Lund, Sweden.
    Ibison, M.G.
    University of Liverpool and Cockcroft Institute, Daresbury, UK.
    Welsch, C.P
    University of Liverpool and Cockcroft Institute, Daresbury, UK.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. University West, Department of Engineering Science, Research Enviroment Production Technology West.
    The Ess Target Proton Beam Imaging Systemas In-Kind Contribution2017In: Proceedings of IPAC2017, Copenhagen, Denmark, 2017, p. 3422-3425Conference paper (Refereed)
  • 3.
    Agic, Adnan
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Analysis of entry phase in intermittent machining2018Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cutting forces and vibrations are essential parameters in the assessment of a cutting process. As the energy consumption in the machining process is directly affected by the magnitude of the cutting forces it is of vital importance to design cutting edges and select process conditions that will maintain high tool performance through reduced energy consumption. The vibrations are often the cause of poor results in terms of accuracy, low reliability due to sudden failures and bad environmental conditions caused by noise. The goal of this work is to find out how the cutting edge and cutting conditions affect the entry conditions of the machining operation. This is done utilizing experimental methods and appropriate theoretical approaches applied to the cutting forces and vibrations. The research was carried out through three main studies beginning with a force build-up analysis of the cutting edge entry into the workpiece in intermittent turning. This was followed by a second study, concentrated on modelling of the entry phase which has been explored through experiments and theory developed in the first study. The third part was focused on the influence of the radial depth of cut upon the entry of cutting edge into the workpiece in a face milling application. The methodology for the identification of unfavourable cutting conditions is also explained herein. Important insights into the force build-up process help addressing the correlation between the cutting geometries and the rise time of the cutting force. The influence of the nose radius for a given cutting tool and workpiece configuration during the initial entry is revealed. The critical angle i.e. the position of the face milling cutter that results in unfavourable entry conditions has been explained emphasizing the importance of the selection of cutting conditions. Finally, the theoretical methods utilized for the evaluation of the role of cutting edge geometry within entry phase dynamics has been explored. This has revealed the trends that are of interest for selection of cutting conditions and cutting edge design.

  • 4.
    Agic, Adnan
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Seco Tools, Fagersta, Sweden.
    Eynian, Mahdi
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Hägglund, S.
    Seco Tools, Fagersta, Sweden.
    Ståhl, Jan-Eric
    Lund University, Production and Materials Engineering, Lund, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Influence of radial depth of cut on dynamics of face milling application2016In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-9Conference paper (Refereed)
    Abstract [en]

    The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavourable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. The radial depth of cut in combination with milling cutter geometry might under some circumstances give unfavourable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon originates from the geometrical features that affect the rise time of the cutting edge engagement into work piece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult to cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the work piece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behaviour is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.

  • 5.
    Agic, Adnan
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Eynian, Mahdi
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Hägglund, S.
    Seco Tools, Fagersta, Sweden.
    Ståhl, J-E
    Lund University ,Production and Materials Engineering, Lund Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Influence of radial depth of cut on entry conditions and dynamics in face milling application2017In: Journal of Superhard Materials, ISSN 1063-4576, Vol. 39, no 4, p. 259-270Article in journal (Refereed)
    Abstract [en]

    The choice of milling cutter geometry and appropriate cutting data for certain milling application is of vital importance for successful machining results. Unfavorable selection of cutting conditions might give rise to high load impacts that cause severe cutting edge damage. Under some circumstances the radial depth of cut in combination with milling cutter geometry might give unfavorable entry conditions in terms of cutting forces and vibration amplitudes. This phenomenon is originated from the geometrical features that affect the rise time of the cutting edge engagement into workpiece at different radial depths of cut. As the radial depth of cut is often an important parameter, particularly when machining difficult-to-cut materials, it is important to explore the driving mechanism behind vibrations generation. In this study, acceleration of the workpiece is measured for different radial depths of cut and cutting edge geometries. The influence of the radial depth of cut on the dynamical behavior is evaluated in time and frequency domains. The results for different radial depths of cut and cutting geometries are quantified using the root mean square value of acceleration. The outcome of this research study can be used both for the better cutting data recommendations and improved tool design.

  • 6.
    Agic, Adnan
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Seco Tools, Fagersta, Sweden.
    Eynian, Mahdi
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Ståhl, J. -E
    Lund University, Production and Materials Engineering, Lund, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Dynamic effects on cutting forces with highly positive versus highly negative cutting edge geometries2019In: International Journal on Interactive Design and Manufacturing, ISSN 1955-2513, E-ISSN 1955-2505Article in journal (Refereed)
    Abstract [en]

    Understanding the influence of the cutting edge geometry on the development of cutting forces during the milling process is of high importance in order to predict the mechanical loads on the cutting edge as well as the dynamic behavior on the milling tool. The work conducted in this study involves the force development over the entire engagement of a flute in milling, from peak force during the entry phase until the exit phase. The results show a significant difference in the behavior of the cutting process for a highly positive versus a highly negative cutting edge geometry. The negative edge geometry gives rise to larger force magnitudes and very similar developments of the tangential and radial cutting force. The positive cutting edge geometry produces considerably different developments of the tangential and radial cutting force. In case of positive cutting edge geometry, the radial cutting force increases while the uncut chip thickness decreases directly after the entry phase; reaching the peak value after a certain delay. The radial force fluctuation is significantly higher for the positive cutting edge geometry. The understanding of such behavior is important for modelling of the milling process, the design of the cutting edge and the interactive design of digital applications for the selection of the cutting parameters.

  • 7.
    Agic, Adnan
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. Seco Tools, Fagersta, Sweden.
    Eynian, Mahdi
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Ståhl, J. -E
    Lund University, Production and Materials Engineering, Lund, Sweden.
    Beno, Tomas
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Experimental analysis of cutting edge effects on vibrations in end milling2019In: CIRP - Journal of Manufacturing Science and Technology, ISSN 1755-5817, E-ISSN 1878-0016, Vol. 24, p. 66-74Article in journal (Refereed)
    Abstract [en]

    The ability to minimize vibrations in milling by the selection of cutting edge geometry and appropriate cutting conditions is an important asset in the optimization of the cutting process. This paper presents a measurement method and a signal processing technique to characterize and quantify the magnitude of the vibrations in an end milling application. Developed methods are then used to investigate the effects of various cutting edge geometries on vibrations in end milling. The experiments are carried out with five cutting edge geometries that are frequently used in machining industry for a wide range of milling applications. The results show that a modest protection chamfer combined with a relatively high rake angle has, for the most of cutting conditions, a reducing effect on vibration magnitudes. Furthermore, dynamics of a highly positive versus a highly negative cutting geometry is explored in time domain and its dependency on cutting conditions is presented. The results give concrete indications about the most optimal cutting edge geometry and cutting conditions in terms of dynamic behavior of the tool.

  • 8.
    Ahmadpour, A.
    et al.
    Amirkabir University of Technology, Department of Mechanical Engineering, Tehran, Iran.
    Noori Rahim Abadi, Seyyed Mohammad Ali
    University West, Department of Engineering Science, Division of Welding Technology.
    Thermal-hydraulic performance evaluation of gas-liquid multiphase flows in a vertical sinusoidal wavy channel in the presence/absence of phase change2019In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 138, p. 677-689Article in journal (Refereed)
    Abstract [en]

    Turbulent gas-liquid multiphase flows with and without phase change in a vertical wavy channel are addressed. The multiphase flow field is resolved using the volume of fluid method (VOF), and the flow equations are discretized and numerically solved by the well-known finite volume method. As a multiphase system without mass transfer, air/water flow is considered. It is shown that numerical simulation is well capable of predicting the various multiphase flow regimes ranging from slug to bubbly flows inside wavy channels. Moreover, accurate predictions of overall pressure drop are provided by numerical solutions for various air and water flow rates and the phase shift angle between wavy channel walls. Additionally, condensing flows of refrigerant R134a are simulated inside wavy channels. It is found that for almost all the cases considered in the present study, the convective heat transfer coefficient is higher in wavy channels in respect to straight channels. However, a significant pressure drop penalty is observed especially for high mass fluxes across wavy channels. Therefore, the use of the wavy channels for the enhancement of condensing heat transfer is only advisable for low mass fluxes with the phase shift angle of 180°. © 2019 Elsevier Ltd

  • 9. Ajay, A.
    et al.
    Raja, V. S.
    Sivakumar, G.
    Joshi, Shrikant V.
    Hot corrosion behavior of solution precursor and atmospheric plasma sprayed thermal barrier coatings2015In: Corrosion Science, Vol. 98, p. 271-279Article in journal (Refereed)
    Abstract [en]

    Hot corrosion behavior of solution precursor plasma spray (SPPS) thermal barrier coating (TBC) in molten salt mixtures of 90wt.% Na<inf>2</inf>SO<inf>4</inf>+5wt.% V<inf>2</inf>O<inf>5</inf>+5wt.% NaCl and 50wt.% Na<inf>2</inf>SO<inf>4</inf>+50wt.% V<inf>2</inf>O<inf>5</inf> at 900°C is compared vis-à-vis atmospheric plasma spray (APS) coating. APS TBCs show better hot corrosion resistance than SPPS TBCs in both the salt mixtures. The vertical cracks in SPPS coatings, meant for strain tolerance and high thermal cycling life, serve as channels for transporting salts across the coating to bond coat/top coat interface and accelerate failure. © 2015 Elsevier Ltd.

  • 10.
    Algenaid, Wael
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Ganvir, Ashish
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Calinas, Rosa Filomena
    Innovnano materials, Coimbra, Portugal.
    Varghese, Johny
    University of Hyderabad, Hyderabad, India.
    Rajulapati, Koteswararao V.
    University of Hyderabad, Hyderabad, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Influence of microstructure on the erosion behaviour of suspension plasma sprayed thermal barrier coatings2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 375, p. 86-99Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) are applied on the surface of hot parts of gas turbine engines to increase the turbine efficiency by providing thermal insulation and to protect the engine parts from the harsh environment. Typical degradation of TBCs can be attributed to bond coat oxidation, thermal stress etc. In addition to this, erosion can also lead to partial or complete removal of the TBCs especially when the engine operates under erosive environment such as flying over desert area, near active volcanic or offshore ocean environment. Suspension Plasma Spraying (SPS) is a promising technique for TBC applications by virtue of its ability to produce a strain-tolerant porous-columnar microstructure that combines the benefits of both electron beam physical vapor deposited (EB-PVD) as well as atmospheric plasma sprayed (APS) coatings. This work investigates the influence of various coating microstructures produced by SPS on their erosion behavior. Six different coatings with varied microstructures produced using different suspensions with distinct characteristics were studied and their erosion resistance was compared. Results showed significant influence of SPS TBCs microstructures on the erosion resistance. Furthermore, the erosion resistance of SPS TBCs showed a close correlation between fracture toughness and the erosion rate, higher fracture toughness favours superior erosion resistance. © 2019 Elsevier B.V.

  • 11.
    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.
    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.

  • 12.
    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.
    Pejryd, Lars
    University West, Department of Engineering Science, Division of Production Engineering.
    Energy and Cost Efficiency in CNC Machining from a Process Planning Perspective2011In: 9th Global Conference on Sustainable Manufacturing: Sustainable Manufacturing –Shaping Global Value Creation / [ed] Günther Seliger, 2011, p. 383-389Conference paper (Refereed)
    Abstract [en]

    The role of process planning as an enabler for cost efficient and environmentally benign CNC machining is investigated in the paper. Specific energy is used as the principal indicator of energy efficient machining and different methods to calculate and estimate this is exemplified and discussed. The interrelation between process planning decisions and production outcome is sketched and process capability can be considered as one factor of green machining. A correlation between total machining cost and total energy use was shown for an experimental case. However, to generalise conclusions, the importance of having reliable data during process planning to make effective decisions should not be underestimated.

  • 13.
    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
    University West, Department of Engineering Science, Division of Production Engineering.
    Process planning for cnc machining of swedish subcontractors: A web survey2014In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 17, p. 732-737Article in journal (Refereed)
    Abstract [en]

    Process planning of CNC machining is critical to ensure cost, time and quality parameters of manufacturing operations. At the heart of process planning is, typically the process planner, who must make a multitude of decisions regarding machines, cutting strategies, tools and process parameters etc. Today there are a number of different tools and methods available to aid the process planner. This paper explores today’s industrial use of some of these aids and outlinespotential underlying reasons for the current state. The empirical data is based on a questionnaire survey of Swedish CNC machining sub-contractors. The main conclusion is that despite a long history of development of various aids (CAD/CAM, PLM standards etc.) there is still a large proportion of the industry, which has not yet adopted these aids. By the responding companies 32% do not use any CAM system and only 2% use a PLM system. On the other side of the spectrum is a group of 25% that uses CAM in 75% or more of their planned products. The learning from this survey can be used to better understand the industrial needs and focus research and development efforts.

  • 14.
    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.

  • 15.
    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., Hoboken, NJ, USA: John Wiley & Sons, 2014, p. 249-262Conference paper (Refereed)
  • 16.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Jacobsson, J.
    Brederholm, A.
    Hänninen, H.
    Improved understanding of Varestraint Testing: Nickel-based superalloys2016In: Cracking Phenomena in Welds IV / [ed] Boellinghaus, T., Lippold, J. C. and Cross, C. E., Springer Publishing Company, 2016Conference paper (Refereed)
    Abstract [en]

    Information about the book:

    This is the fourth volume in the well-established series of compendiums devoted to the subject of weld hot cracking. It contains the papers presented at the 4th International Cracking Workshop held in Berlin in April 2014. In the context of this workshop, the term “cracking” refers to hot cracking in the classical and previous sense, but also to cold cracking, stress-corrosion cracking and elevated temp. solid-state cracking.  A variety of different cracking subjects are discussed, including test standards, crack prediction, weldability determination, crack mitigation, stress states, numerical modelling, and cracking mechanisms.  Likewise, many different alloys were investigated such as aluminum alloys, copper-aluminum dissimilar metal, austenitic stainless steel, nickel base alloys, duplex stainless steel, creep resistant steel, and high strength steel.

  • 17.
    Andersson, Joel
    et al.
    University West, Department of Engineering Science, Division of Manufacturing Processes.
    Jacobsson, J.
    Lundin, C.
    A Historical perspective on Varestraint testing and the importance of testing parameters2016In: Cracking Phenomena in Welds IV / [ed] Boellinghaus, T., Lippold, J. C. and Cross, C. E., Springer Publishing Company, 2016Conference paper (Refereed)
  • 18.
    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, Hoboken, NJ, USA: John Wiley & Sons, 2014, p. 181-192Conference paper (Refereed)
  • 19.
    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.

  • 20.
    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)
  • 21.
    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)
  • 22.
    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)
  • 23.
    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.

  • 24.
    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)
  • 25.
    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.

  • 26.
    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.

  • 27.
    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.

  • 28.
    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.

  • 29.
    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., Hoboken, NJ, USA: John Wiley & Sons, 2014, p. 425-436Conference paper (Refereed)
  • 30.
    Andersson, Oscar
    et al.
    KTH Royal Institute of Technology, Department of Production Engineering and XPRES, Stockholm, Sweden.
    Fahlström, Karl
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Melander, Arne
    KTH Royal Institute of Technology, Department of Production Engineering and XPRES, Stockholm, Sweden.
    Experiments and efficient simulations of distortions of laser beam–welded thin-sheet close beam steel structures2019In: Proceedings of the Institution of mechanical engineers. Part B, journal of engineering manufacture, ISSN 0954-4054, E-ISSN 2041-2975, Vol. 233, no 3, p. 787-796Article in journal (Refereed)
    Abstract [en]

    In this article, geometrical distortions of steel structures due to laser beam welding were analyzed. Two 700-mm-long U-beam structures were welded in overlap configurations: a double U-beam structure and a U-beam/flat structure. The structures were in different material combinations from mild steel to ultrahigh-strength steel welded with different process parameters. Different measures of distortions of the U-beam structures were evaluated after cooling. Significant factors of the welding process and the geometry of the structures were identified. Furthermore, welding distortions were modeled using two predictive finite element simulation models. The previously known shrinkage method and a newly developed time-efficient simulation method were evaluated. The new model describes the effects of expansion and shrinkage of the weld zone during welding and material plasticity at elevated temperatures. The new simulation method has reasonable computation times for industrial applications and improved agreement with experiments compared to the often used so-called shrinkage method. © 2018, IMechE 2018.

  • 31.
    Aranke, Omkar
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Effect of spray parameters on micro-structure and lifetime of suspension plasma sprayed thermal barrier coat-ings2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fabrication of Thermal Barrier Coatings (TBCs) with higher lifetime and relatively cheaper processes is of particular interest for gas turbine applications. Suspension Plasma Spray (SPS) is capable of producing coatings with porous columnar structure, and it is also a much cheaper process compared to the conventionally used Electron Beam Physical Vapour Dep-osition (EB-PVD). Although TBCs fabricated using SPS have lower thermal conductivity as compared to other commonly used processes, they are still not commercialized due to their poor lifetime expectancy.

    Lifetime of TBCs is highly influenced by the top coat microstructure. The objective of this work was to study and evaluate the top coat microstructure produced using axial SPS with different process parameters. 8 wt. % Yttria Stabilized Zirconia (YSZ) suspension with 25 % solid load in ethanol was used to spray the top coat. The bond coat was deposited on Has-telloy-X substrates using a NiCoCrAlY powder by High Velocity Air Fuel (HVAF) spray with same process parameters. Influence of the microstructure on lifetime of the coatings was of particular interest in this work. The coating microstructure was analysed using Scanning Electron Microscope (SEM) and it was observed that axial SPS is capable of producing TBCs with varied top coat microstructure from highly porous to densely packed columnar microstructure. The lifetime of the coatings was determined by Thermal Cyclic Fatigue (TCF) testing and Burner Rig Testing (BRT). Porosity and Thermal conductivity of the coat-ings was determined by Image Analysis and Laser Flash Analysis (LFA) respectively.

    From the results obtained, it can be concluded that axial SPS could be a promising method of producing TBCs with low thermal conductivity & high lifetime for high temperature gas turbine applications.

  • 32.
    Aranke, Omkar
    et al.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Gupta, Mohit Kumar
    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.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Kjellman, Björn
    GKN Aerospace Sweden AB, Trollhättan, Sweden.
    Microstructural Evolution and Sintering of Suspension Plasma-Sprayed Columnar Thermal Barrier Coatings2019In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, no 1-2, p. 198-211Article in journal (Refereed)
    Abstract [en]

    Suspension plasma spray (SPS) is capable of producing coatings with porous columnar structure, and it is also a much cheaper process compared to the conventionally used electron beam physical vapor deposition (EB-PVD). Although TBCs with a columnar microstructure that are fabricated using SPS have typically lower thermal conductivity than EB-PVD, they are used sparingly in the aerospace industry due to their lower fracture toughness and limited lifetime expectancy. Lifetime of TBCs is highly influenced by the topcoat microstructure. The objective of this work was to study the TBCs produced using axial SPS with different process parameters. Influence of the microstructure on lifetime of the coatings was of particular interest, and it was determined by thermal cyclic fatigue testing. The effect of sintering on microstructure of the coatings exposed to high temperatures was also investigated. Porosity measurements were taken using image analysis technique, and thermal conductivity of the coatings was determined by laser flash analysis. The results show that axial SPS is a promising method of producing TBCs having various microstructures with good lifetime. Changes in microstructure of topcoat due to sintering were seen evidently in porous coatings, whereas dense topcoats showed good resistance against sintering.

  • 33. Archana, M. S.
    et al.
    Srikanth, Vvss
    Joshi, Shrikant. V.
    Joardar, J.
    Influence of applied pressure during field-assisted sintering of Ti(C,N)-WC-FeAl based nanocomposite2015In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 41, no 2, p. 1986-1993Article in journal (Refereed)
    Abstract [en]

    Ti(C,N)-WC-FeAl based nanocomposites are processed by field-assisted sintering at 1500 degrees C. The phase and microstructural evolution during the process under the influence of different applied pressures of 30, 50 and 100 MPa are studied using x-ray diffraction and scanning electron microscopy. Lattice parameters of (Ti,W)(C,N) solid solution and binder phases after sintering are found to vary with applied pressure. The nanocomposite grains are observed to possess a core-rim microstructure. Microstructural variations in terms of type, size and fraction of "corerim" structure as a function of applied pressure are investigated. The hardness and indentation fracture toughness values are in the range of 17.6-18.4 GPa and 5.9-6.8 MPa root m, respectively. These values are comparable with those reported for Ti(C,N)-based composites with metal binder. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

  • 34.
    Arsenault, B.
    et al.
    Industrial Materials Institute, NRC, Boucherville, Que., Canada.
    Gougeon, P.
    University West, Department of Technology, Mathematics and Computer Science.
    Verdier, M.
    Université de Technologie Belfort-Montbéliard, Laboratoire d'Etudes et des Recherches sur les Materiaux les Procedes et les Surfaces (LERMPS).
    Duquesnay, D. L.
    Royal Military College of Canada, Department of Mechanical Engineering.
    Aluminum protective coatings - Fatigue and bond strength properties with respect to surface preparation techniques: Laser ablation, shot peening and grit blasting2006In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 45, no 1, p. 49-58Article in journal (Refereed)
    Abstract [en]

    Aluminum coatings can provide galvanic cathodic protection for several metals and alloys. In order to be a suitable protective solution on structural components, the mechanical integrity must be preserved. In particular, the fatigue properties are a challenge for thermal spray protective coatings on mechanical structures. To address the issue of the fatigue integrity of 7075 aluminum alloy with an arc sprayed protective coating, different surface preparations prior to arc spraying were considered. In the present work, a feasibility study was performed using laser ablation as a surface preparation technique before or during arc spraying of coatings through collaboration between the LERMPS laboratory in France, the National Research Council of Canada and the Royal Military College of Canada. Both fatigue and adhesive properties of aluminum coatings were evaluated in relation to substrate surface preparation techniques including laser ablation (PROTAL® process), grit blasting and shot peening. Results indicate that a combination of key conditions including using nitrogen as the arc spray gas, shot peening and proper laser energy density for ablation provides high fatigue resistance of metallic coated 7075 alloy substrates. Specimens prepared under these conditions show a similar fatigue resistance to uncoated substrates. © Canadian Institute of Mining, Metallurgy and Petroleum.

  • 35.
    Asala, G.
    et al.
    University of Manitoba, Winnipeg, R3T 5V6, Canada .
    Andersson, Joel
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Ojo, Olanrewaj A.
    University of Manitoba, Winnipeg, R3T 5V6, Canada .
    Precipitation behavior of gamma′ precipitates in the fusion zone of TIG welded ATI 718Plus®2016In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 87, no 9-12, p. 2721-2729Article in journal (Refereed)
    Abstract [en]

    The precipitation behavior of the main strengthening phase, γ′ precipitates, in ATI 718Plus® superalloy after Tungsten Inert Gas (TIG) welding and postweld heat treatments has been studied. In contrast to electron beam welding, where no γ′ precipitates are reported to form in the as-welded condition, analytical transmission electron microscopy study in this work revealed the formation of γ′ precipitates after the TIG welding, albeit in a non-uniform distribution manner. This is attributable to a more extensive elemental microsegregation that occurred into the interdendritic liquid and slower cooling rate during the TIG welding, which also induced the formation of interdendritic Nb-rich Laves phase particles and MC-type carbides. Theoretical calculations were performed to study the influence of Nb microsegregation, on both the kinetics and extent of γ′ precipitation, and the results agree with experimental observations. It is found that the precipitation kinetics, and not the extent of γ′ precipitate formation in the fusion zone, during postweld heat treatments is affected by the micro-segregation of Nb that produced Laves phase particles during the weld solidification.

  • 36.
    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.

  • 37.
    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.

  • 38.
    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, O. A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    A study of the dynamic impact behaviour of IN 718 and ATI 718Plus® superalloys2019In: Philosophical Magazine, ISSN 1478-6435, E-ISSN 1478-6443, Vol. 99, no 4, p. 419-437Article in journal (Refereed)
    Abstract [en]

    The dynamic impact response of IN 718 and ATI 718Plus®, in both the solution heat treated and age-hardened conditions, were investigated at different deformation temperatures and strain rates using a direct impact Hopkinson pressure bar. Analyses of the results provide a vital but previously not reported information that the ATI 718Plus® offers a higher resistance to damage during high strain rate ballistic impact deformation compared to the most widely used Iron-nickel based superalloy, Inconel 718. ATI 718Plus® showed higher strain hardening and strain rate sensitivity, in both heat treatment conditions, than IN 718. The difference in the deformation behaviour of both alloys, in the annealed condition, is attributable to the compositional modification in ATI 718Plus® which has been reported to lower its stacking fault energy and increases the tendency for deformation twinning. However, in the age-hardened condition, the difference is believed to be related to the disparity in the operative strengthening mechanism, of the precipitates present in both alloys. Furthermore, a higher susceptibility to strain location and the formation of adiabatic shear band, in aged IN 718, is attributable to the stronger temperature-softening characteristics observed in the alloy and to the limited strain hardening tendency under dynamic impact loading. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

  • 39.
    Asala, Gbenga
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, R3T 5V6, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Ojo, Olanrewaj A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, R3T 5V6, Canada.
    Analysis and constitutive modelling of high strain rate deformation behaviour of wire-arc additive-manufactured ATI 718Plus superalloy2019In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 3, no 1-4, p. 1419-1431Article in journal (Refereed)
    Abstract [en]

    A fundamental prerequisite for obtaining realistic finite element simulation of machining processes, which has become a key machinability assessment for metals and alloys, is the establishment of a reliable material model. To obtain the constitutive model for wire-arc additive-manufactured ATI 718Plus, Hopkinson pressure bar is used to characterise the flow stress of the alloy over a wide range of temperatures and strain rates. Experiment results show that the deformation behaviours of as-deposited ATI 718Plus superalloy are influenced by the applied strain rate, test temperature and strain. Post-deformation microstructures show localised deformation within the deposit, which is attributable to the heterogeneous distribution of the strengthening precipitates in as-deposited ATI 718Plus. Furthermore, cracks are observed to be preferentially initiated at the brittle eutectic solidification constituents within the localised band. Constitutive models, based on the strain-compensated Arrhenius-type model and the modified Johnson-Cook model, are developed for the deposit based on experimental data. Standard statistical parameters, correlation coefficient (R), root-mean-square error (RMSE) and average absolute relative error (AARE) are used to assess the reliability of the models. The results show that the modified Johnson-Cook model has better reliability in predicting the dynamic flow stress of wire-arc-deposited ATI 718Plus superalloy. © 2019, Springer-Verlag London Ltd., part of Springer Nature.

  • 40.
    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

  • 41.
    Asala, Gbenga
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, R3T 5V6, Canada.
    Andersson, Joel
    University West, Department of Engineering Science, Division of Welding Technology.
    Ojo, Olanrewaj A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, R3T 5V6, Canada.
    Improved dynamic impact behaviour of wire-arc additive manufactured ATI 718Plus®2018In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 738, p. 111-124Article in journal (Refereed)
    Abstract [en]

    The dynamic response and impact resistance of wire-arc additive manufactured (AMed) and wrought ATI 718Plus in different heat treatment conditions are characterised by using a direct impact Hopkinson pressure bar system. In addition, microstructural analyses of the alloys, before and after impact, are characterised by using advanced microscopy techniques, including scanning electron and transmission electron microscopies. The experimental results show that the impact resistance of the AMed alloy in the as-processed condition is inferior to that of the wrought alloy. The lower impact resistance is attributed to the presence of eutectic solidification constituents in the interdendritic regions and to the inhomogeneous distribution of the strengthening precipitates in the deposit. After the application of the recommended heat treatment for ATI 718Plus, excessive formation of η-phase particles are observed in the microstructure in addition to Laves phase particles. Since the recommended heat treatment for ATI 718Plus is not sufficient to eliminate the deleterious phases and optimise the properties of the alloy, a novel heat treatment procedure is proposed. Dynamic impact study of the AMed alloy after the application of the proposed approach shows that the alloy exhibits a dynamic response and impact resistance comparable to those of the wrought alloy. Furthermore, under high impact momentum, both the wrought and the AMed alloys fail due to the adiabatic shear band. A transmission electron microscopy analysis of the deformed alloys suggests the dissolution of the γ’ precipitates in the shear band as well as in the adjacent regions to the shear band. Increase in the rate of dissolution of the precipitates due to strain-assisted diffusion coupled with an increase in the adiabatic temperature during deformation, are likely causes of the dissolution of the precipitates in the shear band regions. © 2018 Elsevier B.V.

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

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

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

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

  • 44. Aulenbach, Donald B.
    et al.
    Meyer, Michael A.
    Vaseduvan, Chittibabu
    Beckwith, Eileen
    Greaves, Kathryn
    Joshi, Shrikant
    Cleseri, Nicholas L.
    Removal of several heavy metals in potw using aluminum salts for phosphorus removal1983In: Proceedings of the Industrial Wastes Symposia, 56th Annual WPCF Conference.; Atlanta, Ga, USA; ; Code 3809, 1983Conference paper (Refereed)
  • 45.
    Awasthi, Shikha
    et al.
    Material Science and Engineering, Indian Institute of Technology, Kanpur, Kanpur, India .
    Goel, Sneha
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Pandey, Chandra Prabha
    Babu Banarasi Das University, Department of Chemistry, Lucknow, India.
    Balani, Kantesh
    Material Science and Engineering, Indian Institute of Technology, Kanpur, Kanpur, India .
    Multi-Length Scale Tribology of Electrophoretically Deposited Nickel-Diamond Coatings2017In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 69, no 2, p. 227-235Article in journal (Refereed)
    Abstract [en]

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

  • 46.
    Azar, Amin S.
    et al.
    SINTEF Mat & Chem, Oslo, Norway.
    Svensson, Lars-Erik
    University West, Department of Engineering Science, Division of Production Engineering.
    Nyhus, Bård
    SINTEF Mat & Chem, Oslo, Norway.
    Effect of crystal orientation and texture on fatigue crack evolution in high strength steel welds2015In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 77, p. 95-104Article in journal (Refereed)
    Abstract [en]

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

  • 47.
    Babu, Bijish
    et al.
    Mechanics of Sold Materials, Luleå University of Technology, SE-971 87, Luleå, Sweden.
    Charles Murgau, Corinne
    University West, Department of Engineering Science, Avdelningen för svetsteknologi (SV).
    Lindgren, Lars-Erik
    Mechanics of Sold Materials, Luleå University of Technology, SE-971 87, Luleå, Sweden.
    Physically Based Constitutive Model of Ti-6Al-4V for Arbitrary Phase CompositionArticle in journal (Other academic)
    Abstract [en]

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

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

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

  • 49.
    Badgujar, Amol C.
    et al.
    Centre for Solar Energy Materials, ARCI, Hyderabad, India.
    Joshi, Shrikant V.
    University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing.
    Dhage, Sanjay R.
    Mechanical and Aerospace Engineering Department, University of California, Los Angeles, USA .
    Process Parameter Impact on Selective Laser Ablation of Bilayer Molybdenum Thin Films for CIGS Solar Cell Applications2018In: Materials focus, ISSN 2169-429X, no 4, p. 556-562Article in journal (Refereed)
    Abstract [en]

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

  • 50.
    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)
1234567 1 - 50 of 724
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