挤压AZ31镁合金压压疲劳行为

Cyclic compression behavior of extruded AZ31 magnesium alloy

研究了挤压AZ31镁合金的压-压疲劳行为,并与拉-拉疲劳行为对比,了解孪生对疲劳行为的影响。结果表明,循环压缩滞后环为非对称的S形的曲线,而循环拉伸滞后环比较对称。循环压缩导致了平均应力显著下降。循环应变硬化存在于循环压缩和循环拉伸两种情况下,但循环压缩表现出较强的循环应变硬化中观察到,该行为可归因于压缩阶段易于孪生,孪晶界起到晶界强化效果。与循环拉伸相比,循环压缩样品的塑性应变幅度更大。循环压缩样品具有较大的疲劳裂纹稳定扩展区面积,表明其具有较为优异的疲劳寿命。断裂表面的残余孪晶在两种情况中均会出现。

In order to investigate the effect of twinning on cyclic behaviors, cyclic tension and cyclic compression tests of extruded AZ31 magnesium alloy were conducted. The results indicated that the hysteresis loops exhibited an asymmetric sigmoidal shape for the cyclic compression test, while the cyclic tension sample showed more symmetric hysteresis loops. The cyclic compression induced mean stress to significantly decrease. The cyclic strain hardening occurred for the two cases. However, stronger cyclic strain hardening was observed in the cyclic compression due to the appearance of residual twins. The cyclic compression sample showed higher plastic strain amplitude than the cyclic tension sample. Finally, the microscopic and macroscopic fracture features were examined. The cyclic compression sample exhibited a larger area of fatigue crack stable propagation zone than the cyclic tension sample. The residual twins appeared in the fracture surface for the two conditions.