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对AZ61镁合金进行反复的扭转变形加工,获得了具有孪晶和细晶梯度层合金表层。采用弯曲试验和低周疲劳试验研究了梯度组织对AZ61镁合金在恒应力疲劳加载条件下的变形行为和疲劳寿命的影响。结果表明:扭转试样从中心层到表层,孪晶层逐渐增多和细晶层晶粒尺寸逐渐减小。梯度组织使得弯曲强度提高185 MPa并且保持延性几乎不降低;同时梯度组织可改变AZ61镁合金的循环应力-应变行为,在低的总应力下,梯度组织可提高AZ61镁合金的疲劳寿命。
The AZ61 magnesium alloy was subjected to repeated torsional deformation to obtain a surface layer with twinning and fine graded gradient layer alloy. The effect of gradient structure on the deformation behavior and fatigue life of AZ61 magnesium alloy under constant stress and fatigue loading was studied by bending test and low cycle fatigue test. The results show that the twins are gradually increased from the center to the surface and the grain size decreases gradually. The gradient structure enhanced the bending strength by 185 MPa and kept the ductility almost unchanged. At the same time, the gradient structure can change the cyclic stress-strain behavior of AZ61 magnesium alloy. Under low total stress, the gradient structure can improve the fatigue life of AZ61 magnesium alloy.