无间隙原子钢高压扭转过程中塑性变形的滞后性研究
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摘要
采用DEFORM-3D有限元分析软件,对无间隙原子钢(IF钢)在高压扭转(HPT)中的扭转阶段大塑性变形(SPD)过程进行模拟仿真,通过分析试样的等效应变分布,得到了IF钢在不同剖面的变形滞后性特征.结果表明,在扭转的前期阶段(不大于2周),IF钢试样表现出大塑性变形的滞后性:试样边缘的等效应变值明显高于心部,且沿径向由边缘到心部数值逐渐变小;与试样的上表面相比,下表面的等效应变明显较高,边缘大塑性变形区域较大,并且随着旋转角度、距心部距离的增加,上表面大塑性变形的滞后性越来越明显.这说明在扭转的前期阶段,试样的中心部及上表面的塑性变形相对滞后,并对其原因进行了初步分析,这与其下模旋转及表面摩擦密切相关,理论分析、显微组织及硬度检测结果均验证了该模拟结果的可靠性.
Deformation lagging characteristics of IF steel disks in the early torsion stage in the process of High-Pressure Torsion(HPT)are investigated with DEFORM-3 D finite analysis software through the effective strain distribution of HPT sample by computer simulation and experimental verification. The results indicate that in the early torsion stage(not more than 2 turns), deformation lagging characteristics will exhibit remarkably in the severe plastic deformation(SPD) process. As to the Equivalent Von Mises strain, values in the sample edge is significantly higher than that in center, gradually decreasing from the edge to the center along the radius direction. Compared with the upper surface of sample, the effective strain of the bottom surface is obviously increasing.The SPD area in upper surface of sample is smaller than bottom surface of sample. Following the increasing rotation angel and the distance from the center, the deformation lagging characteristics of upper surface will appear more obviously. The mechanism of characteristics analysis indicate that the active rotation for the bottom die and friction plays an important role in the deformation lagging process. The theoretical analysis, the micro-structure and hardness investigation all agree well with the simulation results.
Deformation lagging characteristics of IF steel disks in the early torsion stage in the process of High-Pressure Torsion(HPT)are investigated with DEFORM-3 D finite analysis software through the effective strain distribution of HPT sample by computer simulation and experimental verification. The results indicate that in the early torsion stage(not more than 2 turns), deformation lagging characteristics will exhibit remarkably in the severe plastic deformation(SPD) process. As to the Equivalent Von Mises strain, values in the sample edge is significantly higher than that in center, gradually decreasing from the edge to the center along the radius direction. Compared with the upper surface of sample, the effective strain of the bottom surface is obviously increasing.The SPD area in upper surface of sample is smaller than bottom surface of sample. Following the increasing rotation angel and the distance from the center, the deformation lagging characteristics of upper surface will appear more obviously. The mechanism of characteristics analysis indicate that the active rotation for the bottom die and friction plays an important role in the deformation lagging process. The theoretical analysis, the micro-structure and hardness investigation all agree well with the simulation results.
引文
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21 Zhilyaev A,Langdon T.Using high-pressure torsion for metal processing:Fundamentals and applications.Prog Mater Sci,2008,53:893–979
2 Li J,Xu J,Guo B,et al.Shear fracture mechanism in micro-tension of an ultrafine-grained pure copper using synchrotron radiation X-ray tomography.Scripta Mater,2017,132:25–29
3 Faraji G,Kim H S.Review of principles and methods of severe plastic deformation for producing ultrafine-grained tubes.Mater Sci Tech,2017,33 :905–923
4 Park B H,Um H Y,Kim J G,et al.Large deformation behavior of twin-induced plasticity steels under high-pressure torsion.Met Mater Int,2016,22:1003–1008
5 宋月鹏,陈苗苗,高东升,等.高压扭转法制备超细晶材料的研究进展.热加工工艺,2017,3:6–9
6 Song Y P,Chen M M,Xu B Y,et al.Effects of friction and anvil design on plastic deformation during the compression stage of high-pressure torsion.Korean J Metals Mater,2016,54:831–837
7 Song Y,Wang W,Lee D J,et al.Thickness inhomogeneity in hardness and microstructure of copper after the compressive stage in high-pressure torsion.Met Mater Int,2015,21:7–13
8 Xu J,Wang X,Shirooyeh M,et al.Microhardness,microstructure and tensile behavior of an AZ31 magnesium alloy processed by high-pressure torsion.J Mater Sci,2015,50:7424–7436
9 Roh A,Um H Y,Kim D,et al.Influence of high-pressure torsion and hot rolling on the microstructure and mechanical properties of aluminumfullerene composites.J Mater Sci,2017,52:11988–12000
10 Abd El Aal M I.Effect of high-pressure torsion processing on the microstructure evolution and mechanical properties of consolidated micro size Cu and Cu-SiC powders.Adv Powder Tech,2017,28:2135–2150
11 Xu J,Li J,Wang C T,et al.Evidence for an early softening behavior in pure copper processed by high-pressure torsion.J Mater Sci,2016,51:1923–1930
12 Edalati K,Shao H,Emami H,et al.Activation of titanium-vanadium alloy for hydrogen storage by introduction of nanograins and edge dislocations using high-pressure torsion.Int J Hydrogen Energ,2016,41:8917–8924
13 Maier G G,Astafurova E G,Melnikov E V,et al.Evolution of grain-subgrain structure and carbide subsystem upon annealing of a low-carbon low-alloy steel subjected to high-pressure torsion.Phys Met Metallogr,2016,117:1101–1110
14 An X H,Lin Q Y,Sha G,et al.Microstructural evolution and phase transformation in twinning-induced plasticity steel induced by high-pressure torsion.Acta Mater,2016,109:300–313
15 Iwaoka H,Horita Z.High-pressure torsion of thick Cu and Al-Mg-Sc ring samples.J Mater Sci,2015,50:4888–4897
16 Shahmir H,Langdon T G.Characteristics of the allotropic phase transformation in titanium processed by high-pressure torsion using different rotation speeds.Mater Sci Eng-A,2016,667:293–299
17 Alizadeh R,Mahmudi R,Ngan A H W,et al.Superplasticity of a nano-grained Mg-Gd-Y-Zr alloy processed by high-pressure torsion.Mater Sci Eng-A,2016,651:786–794
18 Song Y,Chen M,Xu B,et al.Effect of revolution on inhomogeneous deformation of IF steel in high pressure torsion.MSA,2016,07:673–679
19 宋月鹏,陈苗苗,徐保岩,等.高压扭转IF钢压缩阶段的不均匀变形.材料热处理学报,2017,38:105–110
20 陈苗苗.高压扭转试样不均匀塑变过程仿真及其实验验证.硕士学位论文.泰安:山东农业大学,2017.32–36
21 Zhilyaev A,Langdon T.Using high-pressure torsion for metal processing:Fundamentals and applications.Prog Mater Sci,2008,53:893–979