2219铝合金动态压缩下应变率敏感性行为研究

Strain rate sensitivity behavior of 2219 aluminum alloy under dynamic compression

摘要:

为了研究2219铝合金的应变率敏感性行为,采用分离式霍普金森冲击压杆装置(SHPB)对两种热处理状态(T4态和T6态)2219铝合金进行了动态压缩实验,并利用金相显微镜(OM)和X射线衍射(XRD)对压缩后的试样进行了显微分析。研究发现两种热处理状态下材料应变率超过2000 s-1时,材料的流动应力显著下降,即出现显著的应变率软化行为。基于应变率敏感性行为随真实应变及应变率的二维等高线图,发现在高应变量、高应变率条件下材料表现出负应变率敏感性行为,流动应力随着应变量与应变率的提升而下降。通过理论计算及微观组织表征,发现温升软化和变形带导致的软化作用,是材料在高应变量、高应变率表现出负应变率敏感性行为的重要原因。

关键词:动态加载;2219铝合金;力学行为;热处理;应变率敏感性

Abstract:

In order to study the dynamic mechanical properties of 2219 aluminum alloy, dynamic compression experiments were carried out through split Hopkinson impact pressure bar (SHPB) equipment on 2219 aluminum alloy in two heat treatment states (T4 and T6). The microstructure of the obtained samples is analyzed by OM and XRD. It is found that the flow stress of the material decreases significantly when the strain rate exceeds 2000 s-1 under the two heat treatment conditions, that is, a significant strain rate softening behavior occurs. Based on the two-dimensional contour map of strain rate sensitivity behavior with real strain and strain rate, it is found that the material exhibits negative strain rate sensitivity behavior under the condition of high strain and high strain rate, and the flow stress decreases with the increase of strain and strain rate. Through theoretical calculation and microstructure characterization, it is found that the softening effect caused by temperature rise softening and lamellar grain breakage is an important reason for the negative strain rate sensitivity behavior of the material at a high strain rate and high strain rate.

Key words:dynamic loading; 2219 aluminum alloy; mechanical property; heat treatment; strain rate sensitivity