The deformation mechanism and adiabatic shearing behavior of extruded Mg-8.0Al-0.1Mn alloy in different heat treated states under high-speed impact load
Pengcheng Guo, Qian Tang, Luoxing Li, Chao Xie, Wenhui Liu, Biwu Zhu, Xiao Liu
Abstract
High-speed impact tests were conducted in transverse direction with strain rates (SRs) ranging from 1000 s−1–6000 s−1 to investigate the deformation mechanism and adiabatic shearing behavior of extruded Mg-8.0Al-0.1Mn alloy in as-extruded (AE), low temperature solution-treated (ST1) and high temperature solution-treated (ST2) states. At SR of 6000 s−1, the flow stress exhibits a slight drop after reaching its peak, except that of the ST2 sample. The highest strain rate hardening results in the highest peak stress of the ST1 sample. Deformation is first dominated by basal slip, and then gradually converts to be dominated by a coordinated mechanism between basal slip and twinning. In late stage, it shifts to be dominated by non-basal slip supplemented with twinning and basal slip, and then by a coordinated mechanism between non-basal slip and dynamic recrystallization (DRX). Heat treatment only affects the scope of the dominated mechanism. The adiabatic shear band occurs only at SR of 6000 s−1 with strain of 0.30, which strongly affects the crack propagation and DRX. Interestingly, the DRX only occurs in the AE sample due to the combined effect of adiabatic temperature rise and pre-existing twins.