挤压态AZ31镁合金高周疲劳行为  

High Cycle Fatigue Properties of Extruded AZ31 Magnesium Alloy

作　　者：武艳军[1,2] 朱荣[1] 卢田[1] 王经涛[1] 

机构地区：[1]南京理工大学材料科学与工程学院,江苏南京210094 [2]南京交通职业技术学院机电工程系,江苏南京211188

出　　处：《南京理工大学学报》2011年第1期118-121,共4页Journal of Nanjing University of Science and Technology

基　　金：国家自然科学基金(50901042);南京理工大学科研发展基金

摘　　要：为探讨镁合金拉/压强度不对称对疲劳性能的影响,对AZ31镁合金进行了室温应力控制疲劳实验,研究应变幅、峰值应变、循环能量参数随周次的演化,并采用光学显微镜观察表面形貌。结果表明:疲劳初期AZ31镁合金滞后环呈现不对称,200周次后不对称消失;峰值压缩应变随周次增加而变小,在约200周次时转变为拉伸应变;裂纹在材料表面孪晶带处形核,并沿孪晶面扩展。由于AZ31镁合金独特的织构与晶格特点,疲劳过程中交替出现的孪生与去孪生导致了滞后环的不对称,孪晶在裂纹形核及扩展中具有重要作用。A number of uniaxial stress-controlled cyclic loading experiments are conducted for extruded AZ31 magnesium alloy in order to investigate the influence of tension-compression asymmetry on fatigue properties.The cyclic strain amplitude,peak strain and energy parameter are studied.The results show that the hysteresis loops exhibit asymmetry during initial fatigue cycles,but this asymmetry vanishes after 200 cycles.The peak compressive strain gradually decreases,and it reverses to tensile strain at about 200 cycle.Fatigue crack initiates at the twin bands in the surface,and the crack propagates along with specific twin boundaries.Twining and detwinning behaviors are often observed in the fatigue process due to texture and deformation mechanism,leading to the hysteresis loop asymmetry.The twins are crucial to the crack initiation and propagation.

关 键 词：镁合金 高周疲劳 孪生 去孪生 

分 类 号：TG113.26[金属学及工艺—物理冶金]