中文摘要：

分别研究了挤压变形AZ31B镁合金在非对称载荷与对称载荷下的疲劳行为,结果表明两种加载方式下,疲劳过程随着应变幅的增加,滞回曲线的不对称性均增强;在低应变幅下,位错滑移为主要塑性变形机制;而在较高应变幅下,孪生-去孪生为主要变形机制;同一应变幅下,压-压非对称低应变幅疲劳寿命最长,拉-压对称低应变幅疲劳寿命次之,拉-拉非对称低应变幅疲劳寿命最短.

英文摘要：

The paper focuses on the low cycle fatigue behavior of AZ31B magnesium alloy under symmetric and asymmetric loading. The results show that the asymmetry of the hysteresis is enhanced with strain amplitude increasing. At lower strain amplitude, dislocation slip is the dominant plastic deformation mechanism responsible for cyclic hardening. At high strain amplitude, twinning - detwinning is the key deformation mechanism. During the cyclic fatigue, the elastic strain of the tensile process is larger than that of compressive process. At the same strain amplitude, the longest fatigue life is under incompressive - compressive asymmetric loading, followed by that under the tensile - compressive symmetric loading, and the shortest is under the tensile- tensile asymmetric loading.