A hollow billet Expanding-Reducing Extrusion (ERE) wheel hub forming process was carried out with AZ80 magnesium alloy. The effects of ageing on Low-cycle fatigue (LCF) properties were investigated, and the microstructure was characterized with scanning electronic microscopy (SEM). The LCF testing results exhibited that the stress amplitude increased with increasing ageing time, while the plastic strain decreased with increasing ageing time. Cyclic softening followed by hardening was observed for 0 h and 16 h aged samples; however, there was no obvious cyclic softening or hardening for 36 h aged sample. The tension-compression asymmetry were not obvious due to the low strain, precipitation and the non typical basal texture. Fracture observations indicated that the fatigue cracks were initiated on the surface, and the crack propagation area decreased with increasing ageing time. Thus, it can be concluded that ageing has strong effects on the fatigue life for the studied magnesium...

中文翻译：

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时效对AZ80镁合金轮毂低周疲劳（LCF）性能的影响

用AZ80镁合金进行了中空坯料的胀缩挤压（ERE）轮毂成型工艺。研究了老化对低周疲劳（LCF）性能的影响，并用扫描电子显微镜（SEM）表征了显微组织。LCF测试结果表明，应力幅度随老化时间的增加而增加，塑性应变随老化时间的增加而减小。在0 h和16 h时效样品中观察到了循环软化然后硬化的现象。然而，对于36 h时效的样品，没有明显的周期性软化或硬化。由于低应变，降水和非典型的基础纹理，拉压不对称性不明显。断裂观察表明，疲劳裂纹始于表面，随着时效时间的增加，裂纹扩展面积减小。因此，可以得出结论，老化对所研究的镁的疲劳寿命有很强的影响。