热处理对Al-4%Mg-0.3%Ce挤压变形铝合金疲劳行为的影响

Influence of heat treatment on fatigue behavior of extruded Al-4%Mg-0.3%Ce alloy

为了确定固溶处理和时效处理对Al-4%Mg-0.3%Ce挤压变形铝合金的疲劳变形和断裂行为的影响,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。结果表明,固溶处理可提高Al-4%Mg-0.3%Ce挤压变形铝合金的疲劳寿命,而时效处理则导致合金的疲劳寿命有所降低;不同处理状态的Al-4%Mg-0.3%Ce挤压变形铝合金在较高外加总应变幅下疲劳变形时,均可发生动态应变时效。此外,疲劳断口形貌观察表明,不同处理状态的Al-4%Mg-0.3%Ce挤压变形铝合金中,疲劳裂纹均是以穿晶方式萌生于试样表面并以穿晶方式扩展。

In order to determine the influence of solid solution and aging treatments on fatigue deformation and fracture behavior of the extruded Al-4%Mg-0.3%Ce alloy,low-cycle fatigue tests were performed at room temperature under different total strain amplitudes.The experimental results show that solid solution treatment can enhance fatigue life of the extruded Al4%Mg-0.3%Ce alloy,while aging treatment leads to a decrease in fatigue life of the alloy.At higher total strain amplitudes,dynamic strain aging takes place during fatigue deformation for the extruded Al-4 % Mg- 0. 3 % Ce alloy under different heat treatment. In addition, the observation of fatigued fracture surface reveal that the fatigue cracks initiate at free surface of the fatigue specimens and propagate in a transgranular mode.