Effect of plastic anisotropy and Portevin-Le Chatelier bands on hole-expansion in AA7075 sheets in-T6 and -W tempers

被引:21
作者
Choi, Yumi [1 ,2 ]
Ha, Jinjin [3 ]
Lee, Myoung-Gyu [1 ,2 ]
Korkolis, Yannis P. [4 ]
机构
[1] Seoul Natl Univ, Dept Mat Sci & Engn, Seoul, South Korea
[2] Seoul Natl Univ, RIAM, Seoul, South Korea
[3] Univ New Hampshire, Dept Mech Engn, 33 Acad Way, Durham, NH 03824 USA
[4] Ohio State Univ, Dept Integrated Syst Engn, 1971 Neil Ave, Columbus, OH 43210 USA
基金
美国国家科学基金会; 新加坡国家研究基金会;
关键词
Finite element analysis; Hole-expansion formability; Portevin-Le Chatelier (PLC) effect; 7000 Aluminum alloys-W temper; ALUMINUM-ALLOY SHEETS; DUCTILE FRACTURE; STRAIN-RATE; MECHANICAL-PROPERTIES; TENSILE DEFORMATION; STRENGTH; FORMABILITY; STEEL; PRECIPITATION; PREDICTION;
D O I
10.1016/j.jmatprotec.2021.117211
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Influence of tempers on the hole-expansion formability of an AA7075 aluminum sheet is investigated for -T6 (asreceived) and -W tempers (super saturated by the solution heat treatment followed by water quenching). The hole is prepared by end-milling, to limit the effects of hole preparation on the results and instead highlight the effects of material behavior. A flat-headed punch is used to expand the hole, and digital image correlation captures the strain fields throughout the experiment. The results present that the hole can expand by 70 % more in -W compared to -T6 temper with the lower forming force. In contrast, thickness strain distribution around the hole shows a similar pattern in both tempers except the observation of Portevin-Le Chatelier (PLC) effect in -W temper, which causing the inhomogeneous deformation. In parallel, the numerical simulation of the holeexpansion is performed using a user material subroutine implemented for the elasto-plastic material behavior, including plastic anisotropy, of both tempers. The predictions on the thickness strain variation and average level show good agreement with the experiment for -T6 temper, but less so for -W temper. This is shown to be the effect of PLC bands on the deformation: the material in -T6 temper is mainly governed by plastic anisotropy, but -W temper shows combined effect of plastic anisotropy and PLC bands. Nevertheless, the reasonable predictions of both tempers verify that the numerical framework established in this study can be used for preliminary, computationally-efficient virtual process design with a practical purpose, despite omitting the explicit physics of the PLC effect.
引用
收藏
页数:13
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