纵向冲击压缩下LY12铝合金圆环的塑性失稳

通过对铝合金圆环的纵向冲击压缩研究发现，一定条件下在试件的宏观塑性硬化阶段会出现明显的应力降过程。为揭示此应力降的发生机制，对润滑、细磨、粗磨3种端面粗糙条件下，外径、内径和高度比值为6:3:2的LY12铝合金圆环进行系统的Hopkinson压杆纵向冲击实验。结果表明:应力降主要发生在较大的应变和较高的应变率条件。进一步对实验样品的金相观察发现:应力降产生的内在机制为绝热剪切带的形成和发展，此现象是一种动态塑性失稳的过程。以上结果为金属材料在冲击条件下绝热剪切带产生的研究提供了参考。

Plastic instability of LY12 aluminum alloy ring under longitudinal impact compression

Research on the longitudinal impact compression of an aluminum alloy ring found that an obvious stress-drop process will appear in the macro plastic hardening stage of the specimen under certain conditions.In order to reveal the mechanism of this stress-drop process,we conducted the longitudinal impact compression experiment on LY12 aluminum alloy ring specimens whose ratio of OD,ID and height was 6 ∶ 3 ∶ 2 using the split Hopkinson pressure bar (SHPB) under the three end face roughness conditions:lubrication,fine grinding and rough grinding.The experiment results show that the stress-drop process occurs mainly in the large strain and high strain rate loading conditions.Moreover,the results of the metallurgical analysis of the aluminum alloy ring specimens show that the formation and development of the adiabatic shear band is the intrinsic mechanism of the stressdrop process,which is a dynamic plastic instability.This study can serve as a reference for the study of the heat insulation shear band in metal materials under impact.