AZ91镁合金的应变疲劳行为研究

Study on strain fatigue behavior of magnesium alloy AZ91

研究了铸态和挤压态AZ91镁合金的室温应变疲劳行为。结果表明,铸态镁合金表现为循环应变硬化,而挤压态镁合金可呈现循环应变硬化、软化或循环稳定。与此同时,对两种状态的AZ91镁合金的应变寿命行为和循环应力-应变行为进行了分析测试,确定了相应的室温应变疲劳参数。此外,利用扫描电子显微镜观察分析了铸态和挤压态AZ91镁合金的疲劳裂纹萌生和扩展行为。

The fatigue behavior of as-cast and as-extruded AZ91 maguesium alloys was investigated under rotal strain amplitude control mode. The test results revealed that for the as-east alloy, a cyclic strain hardening behavior could be observed. However, the as-extruded alloy would exhibit cyclie strain hardening, softening or stability. At the same time, both strain fatigue life behavior and cyclic stress-strain curve of as-cast and as-extruded maguesium alloys were analyzed, and thus, the corresponding strain fatigue parameters were determined. In addition, the crack initiation and propagation mechanism of the alloys was suggested based on the SEM observation on fracture surfaces of fatigued speeimens.