Effects of strain rate on the low cycle fatigue behavior of AZ31B magnesium alloy processed by SMAT
Effects of strain rate on the low cycle fatigue behavior of AZ31B magnesium alloy processed by SMAT
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DOI：
10.1016/j.jallcom.2017.11.141
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发表时间：
2018-02-25
影响因子：
6.2
通讯作者：
Wu, Suzhou
中科院分区：
文献类型：
--
作者：
Chen, Gang;Gao, Jianwen;Wu, Suzhou
采用表面机械摩擦处理（SMAT）在AZ31b镁合金表面形成了梯度纳米晶（NC）表面层。在应变控制模式下，研究了应变速率和球尺寸对SMATed试样低周疲劳行为的影响。结果表明，在相同应变速率下，SMATed试样的疲劳寿命明显高于粗晶（CG）试样，且3 mm球处理SMATed试样的疲劳寿命比2 mm球处理SMATed试样的疲劳寿命更长。SMATed试样疲劳寿命的提高主要是由于残余压应力和NC表面层抑制裂纹萌生的共同作用。同时，SMATed和CG试样的疲劳寿命都随着应变速率的增加而增加，这是由于高应变速率有利于孪晶活动，抑制位错滑移，从而提高了抗疲劳裂纹能力，延长了疲劳寿命。(C) 2017 Elsevier B.V.版权所有
A gradient nanocrystallined (NC) surface layer was generated on AZ31b magnesium alloy by means of surface mechanical attrition treatment (SMAT). The effects of strain rate and ball size on low cycle fatigue behavior of the SMATed samples were studied under strain-controlled mode. It is found that under the same strain rate, the fatigue life of the SMATed samples is significantly enhanced compared with the coarse-grained (CG) samples, and that the fatigue life of the SMATed samples treated with 3 mm balls is longer than that of those treated with 2 mm balls. The enhanced fatigue life of the SMATed samples is mainly attributed to the combined influences of compressive residual stress and NC surface layer suppressing the initiation of cracks. Meanwhile, for both the SMATed and the CG samples, the fatigue life increases with increasing strain rate, owing to the fact that high strain rate favors twinning activity and restricts dislocation slip, thus enhancing the fatigue crack resistance and prolonging the fatigue life. (C) 2017 Elsevier B.V. All rights reserved.