微弧氧化对AZ91D镁合金力学性能的影响

INFLUENCE OF MICRO-ARC OXIDATION ON MECHANICAL PROPERTIES OF MAGNESIUM ALLOY AZ91D

利用扫描电镜观察AZ91D镁合金微弧氧化膜形貌,通过静拉伸试验和疲劳试验研究微弧氧化后AZ91D镁合金试件的抗拉强度和疲劳性能,借助体视显微镜和扫描电镜观察疲劳断口形貌。结果表明,微弧氧化陶瓷膜内层致密,具有良好的韧性,并且与基体结合强度高,微弧氧化处理对AZ91D镁合金的抗拉强度没有影响。微弧氧化处理后,在均值S_m=4.72 kN、幅值S_a=3.15 kN、应力比R=0.2、载荷为等幅谱及频率为10 Hz疲劳试验条件下,AZ91D镁合金的平均疲劳寿命为54148次循环,与化学氧化处理相当。

The morphology of micro-arc oxidation coatings on AZ91D alloy was analyzed by scanning electron microscopy.The tensile strength and fatigue property of AZ91D magnesium alloy treated with micro-arc oxidation was investigated by static tensile test and fatigue test.And the fatigue fractograph was analyzed by stereomicroscopy and scanning electron microscopy.The results show that the inner layer of micro-arc oxidation coating was imporous and compact,the compact layer had good ductility and good bonding to the substrates. The bonding strength was high.Micro-arc oxidation treatment had no influence upon the tensile strength of AZ91D.The fatigue test condition was as follows,mean value S_m was 4.72 kN,amplitude value S_a was 3.15 kN, stress ratio R was 0.2,load was constant amplitude spectrum and frequency was 10 Hz.The average fatigue life of AZ91D treated by micro-arc oxidation was 54148 cycles,corresponded to that with chemical oxidation.