【摘要】 通过外加总应变幅控制的拉-压对称疲劳试验,研究常温下挤压AZ31B镁合金在不同应变幅下的疲劳性能。结果表明,除了在低应变幅0.5%外,样品均呈现循环应变硬化;应变幅为0.5%时,样品在初始阶段呈现循环硬化,随后保持应力恒定;在压缩过程中孪晶的产生以及随后的卸载和反向拉伸过程中的去孪晶行为导致了高应变幅下的滞回环形状拉-压不对称现象,而低应变幅0.5%下的滞回环形状基本对称,说明低应变幅下孪生-去孪生现象不明显。在整个疲劳过程中,高应变和低应变下的应力—应变曲线呈现2种不同的滞回环形状,这是由不同疲劳阶段孪生和位错滑移2种不同的变形机制所导致。更多还原

【Abstract】 The strain-controlled fatigue behavior of an extruded AZ31B magnesium alloy was investigated under symmetric loading at different total strain amplitudes.It is found that except for the low strain magnitude of 0.5%,the alloy exhibits obviously cyclic strain-hardening characteristics during fatigue at strain magnitudes of 0.7%,0.9%,1.3% and 1.5%.At the strain of magnitude 0.5%,the alloy exhibits a cyclic hardening characteristic in the initial stage and then a stress constant remaining in the late stage.The hysteresis loop is symmetrical in shape at the strain magnitude of 0.5%,and becomes asymmetrical due to the twinning-detwinning process when the strain magnitude increases.The shape difference of the hysteresis loops between the low and high strain magnitudes was discussed in terms of the differential deformation mechanisms.更多还原