金属型铸造Al-Si-Cu-Er合金的低周疲劳行为

Low-cycle Fatigue Behavior of Permanent-mold Cast Al-Si-Cu-Er Alloy

通过在不同外加总应变幅下进行应变控制的室温低周疲劳试验,探讨了金属型铸造Al-Si-Cu-Er合金的疲劳变形和断裂行为。结果表明,在低周疲劳加载下,金属型铸造Al-Si-Cu-Er合金表现为循环应变硬化、循环稳定;金属型铸造Al-Si-Cu-Er合金的弹性应变幅、塑性应变幅与疲劳断裂时的载荷反向周次之间的关系可分别用Basquin和Coffin-Manson公式描述;金属型铸造Al-Si-Cu-Er合金在低周疲劳加载条件下,裂纹均以穿晶方式萌生于试样表面,并以穿晶方式扩展。

The fatigue deformation and fracture behavior of permanent-mold cast Al-Si-Cu-Er alloy were investigated by low-cycle fatigue test at room temperature under different total strain amplitudes.The results show that permanent-mold cast Al-Si-Cu-Er alloy exhibits cyclic strain hardening and stable cyclic stress response during fatigue deformation,which mainly depend on the imposed total strain.The relation between elastic strain amplitude,plastic strain amplitude and reversals to failure can be described by Coffin-Manson and Basquin equations,respectively.In addition,the fatigue cracks initiate at the free surface of fatigue specimens and propagate in a transgranular mode under low-cycle fatigue.