Cyclic shear deformation and fatigue of extruded Mg-Gd-Y magnesium alloy
Cyclic shear deformation and fatigue of extruded Mg-Gd-Y magnesium alloy
复制标题
挤压Mg-Gd-Y镁合金的循环剪切变形与疲劳
DOI：
10.1016/j.jmst.2019.08.025
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发表时间：
--
影响因子：
10.9
通讯作者：
Zhang Zhenyan
中科院分区：
文献类型：
--
作者：
Wang Fenghua;Feng Miaolin;Jiang Yanyao;Dong Jie;Zhang Zhenyan
采用沿挤压方向制备的管状试件，对挤压后的镁合金(GW83，wt%)进行了循环扭转变形和疲劳试验。控制的剪切应变幅度在0.606%到4.157%之间。在循环扭转过程中观察到拉伸孪晶发生孪晶和脱孪晶，在所有测试的应变幅值下，剪切应力-剪切应变滞后曲线呈现完全对称的形状。当剪切应变幅值大于1.732%时，出现边缘循环软化现象。应变-寿命疲劳曲线出现两个拐点，对应的剪切应变幅值分别为1.040%和1.732%。当剪应变幅值高于上拐点时，疲劳早期裂纹出现在最大剪切面上。当应变幅值低于下扭曲点时，疲劳裂纹平行于最大拉伸面。在相同的等效应变幅值下，纯剪切疲劳寿命远高于拉压疲劳寿命。在相同的塑性应变能密度下，挤压GW83合金的疲劳寿命远高于挤压AZ31B合金。
Deformation and fatigue of extruded Mg-8.0Gd-3.0Y-0.5Zr (GW83, wt%) magnesium (Mg) alloy were experimentally investigated under cyclic torsion using tubular specimen fabricated along the extrusion direction. The controlled shear strain amplitudes ranged from 0.606% to 4.157%. Twinning and detwinning of extension twins are observed to take place during cyclic torsion and the shear stress-shear strain hysteresis loops display a perfectly symmetric shape at all tested strain amplitudes. Marginal cyclic softening is observed when the shear strain amplitude is higher than 1.732%. The strain-life fatigue curve shows two kink points, corresponding to the shear strain amplitude of 1.040% and 1.732%, respectively. When the shear strain amplitude is higher than the upper kink point, early fatigue crack is found to initiate on the maximum shear plane. When the strain amplitude is lower than the lower kink point, fatigue cracking is parallel to the maximum tensile plane. At an identical equivalent strain amplitude, the fatigue life under pure shear is much higher than that under tension-compression. The fatigue life of extruded GW83 alloy is much higher than that of extruded AZ31B alloy at the same plastic strain energy density.