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81.
Yongpeng Tang Koki Matsuda Yoichi Takizawa Manabu Yumoto Yoshiharu Otagiri Zenji Horita 《Materials Science & Technology》2020,36(7):877-886
ABSTRACTThe high-pressure sliding (HPS) process was applied for grain refinement of a pipe form of an Al-3wt%Mg-0.2wt%Sc alloy by developing two types of straining techniques (called in this study anvil sliding and mandrel sliding). To achieve a homogeneous microstructure throughout the cross-section of the pipe, the sample is rotated around the longitudinal axis every after sliding operation by introducing multi-pass technique, named multi-pass HPS (MP-HPS) as developed earlier for rods. The MP-HPS-processed sample shows ultrafine-grained structures with an average grain size of ~260 and ~300?nm after the HPS processing using anvil sliding and mandrel sliding. The samples also exhibit superplasticity with total elongations well more than 400%, respectively. A finite-element method is used to simulate the evolution of strain in the HPS processing and demonstrates that the simulation well represents the experimental results. 相似文献
82.
X.J. Xu G.L. Liu L.J Shi X.N. Cheng L. CaiSchool of Mechanical Engineering Jiangsu University Jiangsu China 《金属学报(英文版)》2004,17(5):682-688
1.IntroductionSuperplasticity possesses many good characteristics such as high elongation, low flow stress and high atom diffusion ability, which make it show good application in metal forming and diffusion bonding of complex shape structure. Up to now, the superplasticity of steel has been more investigated, however the pretreatment in order to obtain fine grain and then superplasticity was often carried out by circular quenchingof typically 3 times and subsequent high-temperature tempering, … 相似文献
83.
Fadi K. Abu-Farha Marwan K. Khraisheh 《Journal of Materials Engineering and Performance》2007,16(2):192-199
As the lightest constructional metal on earth, magnesium (and its alloys) offers a great potential for weight reduction in
the transportation industry. Many automotive components have been already produced from different magnesium alloys, but they
are mainly cast components. Production of magnesium outer body components is still hindered by the material’s inferior ductility
at room temperature. Magnesium alloys are usually warm-formed to overcome this problem; however, it was observed that some
magnesium alloys exhibits superior ductility and superplastic behavior at higher temperatures. More comprehensive investigation
of magnesium’s high temperature behavior is needed for broader utilization of the metal and its alloys. In this work, the
high temperature deformation aspects of the AZ31B-H24 commercial magnesium alloy are investigated through a set of uniaxial
tensile tests that cover forming temperatures ranging between 23 and 500 °C, and constant true strain rates between 2 × 10−5 and 2.5 × 10−2 s−1. The study targets mainly the superplastic behavior of the alloy, by characterizing flow stress, elongation-to-fracture,
and strain rate sensitivity under various conditions. In addition, the initial anisotropy is also investigated at different
forming temperatures. The results of these and other mechanical and microstructural tests will be used to develop a microstructure-based
constitutive model that can capture the superplastic behavior of the material.
This article was presented at the AeroMat Conference, International Symposium on Superplasticity and Superplastic Forming
(SPF) held in Seattle, WA, June 6–9, 2005. 相似文献
84.
Ti-24Al-14Nb-3V-0.5Mo合金的超塑性 总被引:2,自引:0,他引:2
研究了温度及应变速率对Ti-24Al-14Nb-3V-0.5Mo(at.-%)合金超塑性能的影响.试验结果表明,在980℃,3.5×10~(-4)s~(-1)的最佳超塑变形条件下,合金显示出较高的超塑性;应变速率敏感性指数m为0.69,拉伸延伸率El.为818%.根据其细小的α_2+β_0两相组织和等温拉伸的试验方法,确定合金的超塑性属于细晶组织超塑性.在超塑变形过程中,合金无空洞产生,显微组织发生动态粗化. 相似文献
85.
86.
以硬脂酸为过程处理剂,采用等离子体辅助球磨制备表面修饰片状纳米Cu粉,并测试其摩擦学性能。结果表明:在等离子体的快速加热及电致塑性效应协同作用下,Cu粉呈现出超塑性而发生剧烈形变,辅助球磨5h制备的片状纳米Cu粉一次颗粒厚度在20nm左右。等离子体辅助球磨使片状纳米Cu粉体表面吸附并化学键合了非极性基团,Cu粉获得亲油疏水表面特性,在40CA船用润滑油中具有良好的分散性。片状纳米Cu粉严重的变形使其具有极高的活性,在摩擦过程中容易吸附铺展在摩擦副表面,使复合油有更好的抗磨性能。在高载荷、高转速工况下,片状纳米Cu粉显示出良好的减摩自修复效果,有效提高了润滑油的极压抗磨性能。 相似文献
87.
丁水 《武汉理工大学学报(材料科学英文版)》2011,26(1):56-60
ZrO2/Ni nanocomposite was produced by pulse electrodeposition and its superplastic properties were investigated by the tensile and bulging tests. The as-deposited nickel matrix has a narrow grain size distribution with a mean grain size of 45 nm. A maximum elongation of 605% was observed at 723 K and a strain rate of 1.67×10-3s-1 by tensile test. Superplastic bulging tests were subsequently performed using dies with diameters of 1 mm and 5 mm respectively based on the optimal superplastic forming temperature. The effects of forming temperature and gas pressure on bulging process were experimentally investigated. The results indicated that ZrO2/Ni nanocomposite samples can be readily bulged at 723 K with H/d value (defined as dome apex height over the die diameter) larger than 0.5, indicating that the nanocomposite has good bulging ability. SEM and TEM were used to examine the microstructure of the as-deposited and bulged samples. The observations showed that significant grain coarsening occurs during superplastic bulging, and the microstructure is found to depend on the forming temperature. 相似文献
88.
本文介绍了相变超塑性焊接技术。试验表明.W6Mo5Cr4V2-45#钢采用循环相变温度区间520~820℃.应力为σ△=50MPa。σ=20MPa.经8次循环的工艺可实现超塑性焊接。这种焊接工艺具有显著的优越性,是一种值得深入研究的新工艺。 相似文献
89.
JIANG Xinggang WU Qingling CUI Jianzhong MA Longxiang Northeast University of Technology Shenyang China 《金属学报(英文版)》1991,4(7):70-73
The superplasticity of high strength superhard A1 alloy LC4 was improved to a great extent by modified thermomechanical treatment.Its maximum elongation may be up to 2100% un- der deformation at initial strain rate of 8.33×10~(-4) S~(-1) at 510℃.Observations of the microstructure changes revealed that with the increase of the deformation,the grain grows and the alloy exhibits strain hardening.The excellent elongation of the alloy seems due to the in- crease of grain stability under deformation. 相似文献
90.
NiAl基多相金属间化合物的显微组织,超塑性研究 总被引:15,自引:1,他引:14
本文研究了金属间化合物Ni—25Al—25Cr的显微组织和超塑性及其变形机理.该合金的显微组织由NiAl则基体和α-Cr,β-Ni(Al,Cr);γ'-Ni3(Al,Cr)的三元共晶体组成,在NiAl基体中还均匀分布着大量弥散的α-Cr沉淀相在1123—1223K之间以22×10-43.3×10-2S-1的应变速率拉伸变形时.该合金表现出高达480%的超塑性超塑性变形的断裂主要是由于晶界滑移和晶粒转动所产生的空洞和晶内解理所致.本文还对超塑性变形的机理进行了初步讨论. 相似文献