Papers by Keyword: Tensile Properties

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Authors: Gui Rong Li, Yu Tao Zhao, Hong Ming Wang, Gang Chen
Abstract: (Al3Ti)p/6351 composites were in situ synthesized via direct melt reaction between 6351 wrought aluminum alloy and K2TiF6 at 720°C. OM, SEM and EDS are utilized to analyze the microstructure and components of composites. The fusing agents of CaF2 and LiCl are mixed with K2TiF6 to lower the temperature of initial in situ reaction. The volume fraction of Al3Ti is 3%.The size of Al3Ti is in the range of 2~4μm, which is much lowered than that fabricated by conventional process. Due to the calcium element from CaF2 the size of Mg2Si phases are decreased to 1~2μm.The microns of independent silicon phases are also observed in the squeezed section. The grain size of α-Al is fined to 30~40μm, which is due to the disperse effect of Al3Ti. The tensile, yield properties and elongation are at room temperature are 365MPa, 320MPa and 10.2%.
Authors: Y. Nakamura, Norio Kawagoishi, K. Kariya
Abstract: In the present study, the tensile and fatigue properties of extruded 7075 Al alloys subjected to re-solution treatment and then T6, T73 and retrogression-reaging (RRA) tempers were reassessed based upon the microstructural analyses by means of electron backscattering diffraction (EBSD) and X-ray diffraction (XRD). The microstructural analyses indicated that fibrous grains having orientations close to <111> and <001> were preferentially aligned in the extrusion direction and that re-solution treatment increased the fraction of <111> grains. Further the as-received T6 specimens had very high dislocation density as well as fine subgrains, while the re-solution treatment decreased dislocation density considerably and increased grain size. These characteristics explained tensile properties well, by taking into account the effect of precipitates formed by tempers. On the other hand, fatigue strength decreased prominently in all of the specimens, as the relative humidity (RH) was increased from 25% to 85%. T73 and RRA treatments which improve the resistance to stress corrosion cracking (SCC) in static loading were not effective in the humidity-enhanced deterioration in fatigue strength.
Authors: Sushanta Kumar Panigrahi, R. Jayaganthan
Abstract: The mechanical properties and microstructural characteristics of a precipitation hardenable Al 7075 alloy subjected to rolling at liquid nitrogen temperature and room temperature are reported in this present work. The Al 7075 alloy was severely rolled at cryogenic temperature and room temperature and its mechanical properties were studied by using tensile tests and hardness. The microstructural characterization of Al 7075 alloy were made using SEM/EBSD, TEM and DSC. The cryorolled Al 7075 alloys have shown improved mechanical properties as compared to the room temperature rolled Al alloy. The cryorolled Al alloy after 90% thickness reduction exhibits ultrafine grain structure as observed from its TEM micrographs. It is observed that the strength and hardness of the cryorolled materials (CR) at different percentage of thickness reductions are higher as compared to the room temperature rolled (RTR) materials at the same strain due to suppression of dynamic recovery and accumulation of higher dislocations density in the CR materials.
Authors: Kyung Woo Lee, Kug Hwan Kim, Kwang Ho Kim, Dong Il Kwon
Abstract: The development of the instrumented indentation test (IIT), which gives accurate measurements of the continuous variation in indentation load as a function of depth, has paved the way to assessing tensile properties and residual stress in addition to hardness by analyzing the indentation load-depth curve. In this study, analytic models and procedures are presented for evaluating tensile flow properties and residual stress states using IIT. Tensile properties were obtained by defining representative stress and strain beneath the spherical indenter. The evaluation of residual stress is based on the concepts that the deviatoric stress part of the residual stress affects the indentation load-depth curve, and that analyzing the difference between the residual stressinduced indentation curve and the residual stress-free curve permits evaluation of the quantitative residual stress in a target region.
Authors: Lei Shang, Yu Juan Zhang
Abstract: With the improvement of people’s living standard, the traditional warm clothing already cannot satisfy people’s diversified demands about clothes’ comfortableness, functionality and aesthetics. Hygroscopic exothermic fibers as a positive heat production type of warm fibers have attracted much attention. Softwarm heating warm fiber is a kind of new functional material and at the same time it is a representative of hygroscopic exothermic fiber. It can absorb the moisture by skin breathe and transfer it into heat energy through chemical reaction so as to achieve the purpose of warmth. In this paper, warmth property, tensile property, and drapability of softwarm fiber plain knitted fabric were tested, and comfort property, mechanical property and appearance performances of softwarm heating warm fiber fabric were investigated. Our study showed that the wearability of softwarm fiber fabric is fine, especially the warmth property which can meet our needs of warmth to knitted underwear.
Authors: Guo Dong Shi, Min Cong Liu, Sheng Jin
Abstract: One multiscalar microlaminate (MSML) with 5 thick layers of NiCoCrAl whose thickness were different interspersed with 66 thin layer stacks of NiCoCrAl/YSZ was fabricated by EB-PVD. Uniaxial tensile testing was performed and fracture was examined using SEM. The results show that the microlaminate exhibits brittle-like behavior without macroscopic plastic deformation in room temperature tensile tests and the maximum engineering stress is 212MPa. Examination of fracture surfaces from the samples reveals that ceramic layers fail by intergranular brittle fracture between columns, but metal layers display features of both ductile and brittle fracture. It is also found that the thicknesses of metal layers have a great effect on their failure modes. And interfacial debonding and bridging metal layers are observed. Moreover, the resistance of crack propagation in the microlaminate is discussed.
Authors: A. Rose, O. Kessler, Fabian Hoffmann, H.W. Zoch, P. Krug
Abstract: For quenching of age hardenable aluminum alloys today predominantly aqueous quenching media are used, which can lead due to the Leidenfrost phenomenon to a non-uniform cooling of the parts and thus to distortion. In relation to the conventional quenching procedures in aqueous media, gas quenching exhibits a number of technological, ecological, and economical advantages. The quenching intensity can be adjusted by the variable parameters gas pressure, gas velocity as well as the kind of gas and thus can be adapted to the requirements of the component. By the higher uniformity and the better reproducibility, gas quenching offers a high potential to reduce distortion. Cost savings would be possible, because of reduced distortion and therefore less reworking. High-pressure gas quenching with nitrogen or helium, as well as air quenching at ambient pressure in a gas nozzle field was applied to the spray formed aluminum alloy Al-17Si-4Fe-3Cu-0.5Mg-0.4Zr (DISPAL S232). Hardness and tensile tests have been carried out to determine the mechanical properties after gas quenching and aging compared to water quenching. The distortion behavior of a forged aluminum component of the spray formed alloy was examined after gas quenching and after water quenching. Gas quenching showed remarkable advantages regarding distortion.
Authors: L.B. Khokhlatova, I.N. Fridlyander, N.I. Kolobnev, Y.M. Dolzhanski
Authors: Z. Horita
Abstract: The process of severe plastic deformation (SPD) makes it possible to reduce the grain size to the submicrometer or nanometer range in many metallic materials. When the SPD process is applied to age hardenable alloys, it may also be possible to control aging behavior. In this study, a technique of equal-channel angular pressing (ECAP) is used as an SPD process and aging behavior is examined on the three selected Al alloy systems such as Al-Ag, Al-Mg-Si and Al-Si-Ge. The microstructures are observed using transmission electron microscopy and the mechanical properties including hardness are measured. It is shown that the SPD process introduces unusual phenomena in the precipitation process and there should be a potential for enhancement of strength over the conventional age-hardening process or for improvement of ductility while keeping the high strength.
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