在不同温度(300～475 ℃)和应变速率(0.000 5～0.1 s-1)条件下对H18热处理态的2024铝合金进行了高温拉伸试验, 得到了其应力-应变曲线, 结合显微组织观察分析了温度及应变速率对该铝合金流变行为的影响与高温塑性变形时的动态软化机制。结果表明: H18态2024铝合金在300 ℃以上高温进行塑性变形时发生了再结晶, 经过475 ℃、应变速率0.000 5 s-1拉伸变形后, 晶粒呈等轴状;其伸长率随着变形温度升高和应变速率的增大呈现先上升后下降的趋势;最大应力及应变硬化指数随温度的升高或应变速率的降低而下降;应变速率敏感指数随温度的升高而增大。

The influences of temperature and strain rate on the flow behavior, dynamic softening mechanism of H18 2024 aluminum alloy during plastic deformation process at elevated temperatures were investigated, according to the stress-strain curves at temperatures of 300-475 ℃ and strain rates of 0.000 5-0.1 s-1from tensile testing and microstructure observation. Results show that recrystallization took place in plastic deformation of H18 2024 aluminum alloy at elevated temperatures above 300 ℃, and equiaxed grains were obtained after deformation at 475 ℃ with strain rate of 0.000 5 s-1. The tensile elongation of H18 2024 aluminum alloy rose first and then dropped with the increase of temperature and strain rate. The maximum stress and strain hardening index of the aluminum alloy reduced with the increase of temperature or the decline of strain rate, and the strain rate sensitivity index increased when temperature was elevated.