LY12CZ铝合金材料的室温和高温单轴循环变形行为及其时间相关性

Uniaxial Cyclic Deformation of LY12CZ Aluminium Alloy and Its Time-dependence

对LY12CZ铝合金室温和高温下的单轴循环变形行为及其时间相关特性进行了实验研究,重点讨论了环境温度、应力水平、加载波形和峰值保持对材料棘轮行为的影响。结果表明:室温和高温下,LY12CZ铝合金体现出循环硬化特性,并具有明显的应变幅值依赖性;材料的棘轮行为不仅依赖于当前的平均应力和应力幅值大小,还与加载历史密切相关。尽管LY12CZ铝合金在单调拉伸时对应变率的变化不敏感,但其循环棘轮行为具有明显的时间相关特性:有峰值保持时产生的棘轮应变明显大于没有保持时的值,并随保持时间的增加而增大;正弦波形下的棘轮应变大于三角波形下的棘轮应变。

A series of experiments were carried out to observe the cyclic deformation behaviors of LY12CZ aluminium alloy and its time-dependences at room and high temperatures. The main attention was paid to the effects of ambient temperature, stress level, loading waveform and peak stress hold on the ratchetting. It is shown that the LY12CZ aluminium alloy presents cyclic hardening feature and the extent of cyclic hardening depends on the strain amplitude. The ratchetting behavior of the material depends not only on the current stress amplitude and mean stress, but also on the loading histories. Although the LY12CZ aluminium alloy is not sensitive to the variation of strain rate in monotonic tension, its ratchetting behavior presents remarkable time-dependence： i.e., the ratchetting strain produced in the cyclic stressing with peak stress hold is larger than that without any hold and increases with the hold time, and the ratchetting strain produced with sinusoidal waveform is apparently larger than that with the triangular one.