首页期刊导航|Key engineering materials
期刊信息/Journal information
Key engineering materials
Trans Tech Publications Ltd.
Key engineering materials

Trans Tech Publications Ltd.

半月刊

1013-9826

Key engineering materials/Journal Key engineering materials
正式出版
收录年代

    On the Development of Viable Cruciform-Shaped Specimens: Towards Accurate Elevated Temperature Biaxial Testing of Lightweight Materials

    Fadi Abu-FarhaLou Hector Jr.Mohammed Nazzal
    p.93-101页
    查看更多>>摘要：This paper is focused on the development of viable cruciform-shaped specimen geometries where large biaxial plastic deformation can be achieved within their gauge areas. A custom-built balanced biaxial testing fixture is used to plastically deform a variety of carefully-designed AZ31B-H24 magnesium specimens until failure. Images recorded from a digital camera positioned to monitor deformation in the gauge area of each specimen are used to compute the strain fields with a digital image correlation (DIC) algorithm. The viability of each design is validated based on the extent of biaxiality of measured strains and its ability to promote plastic deformation within its gauge area up until failure. The study provides key insights into the influences of certain geometrical parameters on deformation-biaxiality in cruciform specimens.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    High Pressure Waterjets - An Innovative Means of Alpha Case Removal for Superplastically Formed Titanium Alloys

    A. ChillmanM. RamuluM. HashishA. Cantrell...
    p.103-111页
    查看更多>>摘要：Ultra high-pressure waterjets (WJ) have gained consideration as a viable alternative to conventional material removal and cleaning methods such as chemical milling, grit blasting, and grinding. Waterjets have often been considered for the stripping of unwanted coatings, but they also exhibit an inherent ability for the controlled milling of metallic materials. The waterjet material removal process poses a secondary benefit - the material erosion occurs due to the repetitive impact of droplets within the waterjet stream, which also serve to induce compressive residual stresses in the shallow sub-surface layers of the work piece. An experimental study was conducted to explore the removal of the alpha case layer on Superplastically Formed conventional and fine grain Ti-6A1-4V specimens. The resulting surface roughness parameters and completeness of alpha layer removal were characterized. Based on the experimental results, waterjet removal processes may serve as an alternate method for the post-processing of Superplastically Formed titanium alloys.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    A Theoretical Investigation into the Effect of Laser Parameters on the Surface Cleaning of Ti-6Al-4V

    A. DixitMike KeaveyAlan JocelynJerome Way...
    p.113-118页
    查看更多>>摘要：Chemical cleaning has been used for several decades as a surface preparation technique for diffusion bonding. Here we present a theoretical investigation that examines the effect of changes in the process parameters when a laser is used as an alternative to chemical cleaning for surface contaminant removal. Here a theoretical model is described that includes laser beam attenuation in the plasma plume and its effect on evaporation of the material. Using the model, a comprehensive analysis of the effect of different fluences and other parameters for a KrF Excimer laser is presented. Calculations were carried out for a range of peak fluxes from below the ablation threshold to fluxes of the order of 9 × 10~(12) W/m~2. The predicted effects on evaporation, melt depth and surface temperature are reported, illustrated by a number of surface topographic images from preliminary experiments. Finally, optimal parameters for cleaning according to the theoretical investigation are proposed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Superplastic Forming and Diffusion Bonding: Current Cost, Value and Future Trends

    Paul WilsonChristopher Couzins-ShortHoward ChestertonAlan Jocelyn...
    p.119-124页
    查看更多>>摘要：Superplastic Forming and Diffusion Bonding (SPF/DB) have provided some of the lightest, strongest, corrosion resistant, elegant and complex structures ever produced. Thus "At Boeing, SPF is now considered as a baseline design option for many large assemblies" (Dan Sanders, 2000). However, in an ever increasingly cost conscience world, will the process flourish or decline?Cost is the element most scrutinised by society, and is often considered more important than achieving a required specification or delivery of a project on time. In this paper an analysis of the global value of SPF and SPF/DB products will be provided by industrial sector and material type. The cost of the current technology, such as capital plant, consumable materials and labour overheads, will be compared to the current price of SPF products and the degree of 'market pressure' to reduce such costs will be assessed. Such pressures may arise from potential threats from competing technologies, fuel costs or environmental considerations.However, if lowering the 'carbon footprint' of the process, and its cost, could be achieved, together with the production of components and structures of improved weight to strength ratio, SPF technology could be elevated to the first, and principal, choice of designers worldwide.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Contact Sensors for Accurate Monitoring and Prediction of Sheet Deformation during Hydro/Pneumatic Forming Operations

    F. Abu-FarhaM. NazzalO. RawashdehR. Michael...
    p.125-132页
    查看更多>>摘要：In spite of the numerous advantages of hydro/pneumatic forming operations over the conventional mechanical ones, the inability to accurately monitor the progress, and determine the end point, of the process represents a major setback. Therefore, this effort presents a simple technique for providing a direct feedback on the sheet's advancement during the process by implanting contact sensors across the surface of the forming die at selected locations. The technique is shown to be instrumental in providing a means of control over the process particularly for constant pressure forming practices and thus eliminating the need for any trial-and-error runs. More importantly, the light is shed on how the technique can be utilized to validate and improve the constitutive and Finite Element (FE) models of the unique class of lightweight alloys often formed by hydro/pneumatic operations; a matter essentially needed for constant strain rate forming practices.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Friction Stir Processing (FSP) of As-Cast AA5083 for Grain Refinement and Superplasticity

    J.T. HayashiS.K. MenonJ.-Q. SuT.R. McNelley...
    p.135-140页
    查看更多>>摘要：Multi-pass FSP was conducted on continuously-cast (CC) AA5083 materials in the as-cast condition. Stir zone grains were refined to ～1.0 - 3.5μm in size and highly superplastic response was obtained during tension testing of the as-processed materials at 450℃ (>1200 pct. elongation at 10~(-1) s~(-1)). Current models of recrystallization do not predict adequately the highly refined grains and predominantly random textures that are observed in stir zones. Grain refinement during FSP is accompanied by refinement and redistribution of non-deforming constituents in the absence of particle fracture. The mechanics of the homogenization process remain to be established and requirements for redistribution mechanisms will be summarized. Comparison reveals that results from FSP of the as-cast material are superior to those attained in conventional processing.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Friction Stir Processing of Commercial Grade Marine Alloys to Enable Superplastic Forming

    Christopher B. SmithArun MohanRajiv S. MishraMurray Mahoney...
    p.141-151页
    查看更多>>摘要：The use of friction stir processing (FSP) on marine grade aluminum sheet has been investigated with the objective of locally enhancing the material properties. This can potentially allow low cost commercial grade aluminum to be used in superplastic forming applications or further enhance the formability to allow more complex geometries to be formed. FSP has been demonstrated to enable superplasticity (uniform elongations >250%) in 5083-H116 over a range of friction stir processing conditions.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Optimization of the Friction Stir Welding Process for Superplastic Forming and Improved Surface Texture for Titanium Aerospace Structures

    Daniel SandersPaul EdwardsM. RamuluGlenn Grant...
    p.153-167页
    查看更多>>摘要：In friction stir welding (FSW), the semi-circular shaped FSW pin tool feed marks that are left behind varied in depth and shape which are detrimental not only in fatigue performance but also in further processing such as superplastic forming (SPF). Experimental investigation was conducted to determine the effects of changes to the FSW process parameters on the surface roughness of the weld of fine grain 2 mm thick titanium alloy, Ti- 6A1-4V. In addition to optimizing the surface texture of the welds, the superplastic performance of the weld nugget was made to be equal to the superplasticity of the parent metal by altering the spindle speed and feed rate used during FSW to identify the quality in terms of cold weld or hot weld. FSW process conditions of spindle speed of 500 RPM and a feed rate of 150 mm/min was found to produce a uniform deformation in both weld and parent metal when the joint was superplastc formed.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Superplastic Behavior and Microstructure of Titanium (Ti-6Al-4V) Friction Stir Welds Made Under a Variety of Processing Conditions

    P. EdwardsM. RamuluD. Sanders
    p.169-176页
    查看更多>>摘要：Friction Stir Welding of Ti-6Al-4V was performed on 5 mm thickness plate in order to assess the affect of welding conditions on the resulting microstructure and superplastic forming behavior of the joints. A variety of welding conditions were tested and all welds were subsequently Superplastically formed. It was found that the weld parameters do influence the microstructure and degree of superplastic performance of the joints. Spindle speed was found to have the most dominant affect on the resulting microstructure and superplastic forming behavior. Low spindle speed welds lead to fine grained microstructures and highly superplastic welds, relative to the base material, while high spindle speed welds larger grained microstructures and less superplastic welds.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd

    Finite Element Modeling of Superplastic Forming of Tubular Shapes

    Mohammad A. NazzalFadi K. Abu Farha
    p.179-184页
    查看更多>>摘要：Most of the work done on superplastic forming is related to sheet metal forming. Very limited studies have been directed toward investigating the superplastic tube forming process. In this work, Finite Element (FE) simulations are carried out in order to simulate the superplastic tube forming process. The analysis is conducted for the superplastic magnesium alloy AZ31 at 400℃. The results clearly demonstrate that there is a significant difference between tube forming and sheet metal forming in terms of forming pressure profiles. In addition, the effects of tube radius, free forming length, and contact on the tube forming process are investigated.
      原文链接:
    • NETL
    • NSTL
    • Trans Tech Publications Ltd