7039 aluminum alloy target was obliquely penetrated. The microstructure character around the crater was investigated by optical microscopy (OM). A numerical modeling during the impact penetration was established. The results show that, with the bullet penetrating into the 7039 aluminum alloy, the microstructure character around the crater is regular. When the adiabatic softening is insignificant, the adiabatic shear bands (ASB) and cracks around the crater are found. When the adiabatic softening is increased, the adiabatic shear bands coalesce into a wider overlapping shear deformation band, and the adjacent grains are deformed seriously, resulting in a lot of contorted bands. At the end of the penetration process, there are a lot of microbands. The process of bullet oblique impact penetration into the 7039 aluminum alloy can be simulated effectively using Johnson-Cook constitutive model described by Largrane.%采用光学显微镜(OM)分析子弹斜侵彻7039铝合金后弹坑周围的组织特征,并对侵彻过程进行数值模拟.结果表明:子弹侵彻7039铝合金靶材后,弹坑周围的显微组织呈现有规律的特征;当绝热软化作用较弱时,弹坑周围出现绝热剪切带和裂纹;且随着热软化的加强,绝热剪切带聚合成较宽的层叠剪切变形带,紧邻的晶粒严重变形产生扭曲带,侵彻末期组织中形成大量的变形显微带.采用Largrange描述的Johnson-Cook本构模型能够有效地模拟子弹斜冲击侵彻7039铝合金靶材的过程.
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