预变形对AZ31B镁合金循环变形和疲劳行为的影响

Effects of Predeformation on Cyclic Deformation and Fatigue Behavior of AZ31B Magnesium Alloy

通过小应变幅值预循环变形和预压缩变形对挤压态AZ31B合金分别引入了大量位错和孪晶,研究了预变形对AZ31B合金单向变形行为、循环变形行为和疲劳寿命的影响。结果表明:预循环变形能提高单向拉伸屈服强度,对大应变幅值下的疲劳性能几乎没有影响,但在小应变幅值下出现明显的硬化现象,疲劳性能明显下降。预压缩降低了单向拉伸屈服强度,对大应变幅值下的疲劳性能无显著影响,而在小应变幅值下会增大塑性应变能密度,减少疲劳寿命。

A large number of dislocations and twins were introduced into extruded AZ31B alloys by precyclic predeformation with small strain amplitude and precompression deformation, respectively. The effects of predeformation on unidirectional deformation behavior, cyclic deformation behavior and fatigue life of AZ31B alloy were studied. The results show that cyclic predeformation can improve the uniaxial tensile yield strength, and it has little effect on the fatigue performance at large strain amplitude. But under small strain amplitude, the phenomenon of hardening appears obviously, and the fatigue property decreases obviously. Precompression reduces the uniaxial tensile yield strength and has no significant effect on the fatigue performance at large strain amplitude, but it increases the plastic strain energy density and reduces the fatigue life at small strain amplitude.