H70黄铜局域化剪切变形行为研究

Localized Shear Deformation Behavior in H70 Brass

借助分离式霍普金森压杆和金相显微镜研究了高应变速率下H70黄铜中的绝热剪切现象。实验结果表明,当应变速率为5.0×10^4 s^-1、6.0×10^4 s^-1时,加载后H70黄铜中均出现绝热剪切带,且带内原始粗大晶粒发生动态再结晶而细化。另外,随着应变速率从5.0×10^4 s^-1增加到6.0×10^4 s^-1,对应的临界应变和绝热剪切形成能分别从1.346、723.71 kJ/m^3增加到1.578、805.94 kJ/m^3,即随着应变速率的增加,应力坍塌点对应的临界应变和绝热剪切形成能均增加,表明H70黄铜的绝热剪切敏感性随着应变速率增加而降低。

The adiabatic shearing in H70 brass under high strain rate was studied by split Hopkinson pressure bar technique(SHPB)and optical microscope(OM).Results show that the adiabatic shear band appears in H70 brass post loading when the strain rates are 5.0×10^4 s^-1 and 6.0×10^4 s^-1 respectively,and the original coarse grains in the adiabatic shear band underwent dynamic recrystallization and refinement.In addition,as the strain rate increases 5.0×10^4 s^-1 from to 6.0×10^4 s^-1,corresponding critical strain and adiabatic shear forming energy increase from 1.346,723.71 kJ/m^3 to 1.578,805.94 kJ/m^3 respectively,indicating that the adiabatic shear susceptibility of H70 brass increases with the increase of strain rate.