高应变速率轧制AZ31镁合金的组织及微裂纹演变  

Microstructure and Microcrack Evolution of AZ31 Magnesium Alloy During High Strain-rate Rolling

作　　者：肖罡 万泉慧 朱必武[2] 刘筱[2] 刘晓红[3] XIAO Gang;WAN Quanhui;ZHU Biwu;LIU Xiao;LIU Xiaohong(Collaborative Innovation Center of Engineering Technology,Jiangxi University of Applied Science,Nanchang 330100,China;Hunan Engineering Research Center of Forming Technology and Damage Resistance Evaluation for High Efficiency Light Alloy Components,Hunan University of Science and Technology,Xiangtan 411201,China;College of Mechanical Engineering,Jiujiang Vocational and Technical College,Jiujiang 332007,China)

机构地区：[1]江西应用科技学院,工程技术协同创新中心,南昌330100 [2]湖南科技大学,高功效轻合金构件成形技术及耐损伤性能评价湖南省工程研究中心,湘潭411201 [3]九江职业技术学院机械工程学院,九江332007

出　　处：《机械工程材料》2021年第11期18-23,共6页Materials For Mechanical Engineering

基　　金：国家自然科学基金资助项目(52071139,52075159);国家金属材料近净成形工程技术研究中心开放基金项目(2020013);湖南省自然科学基金资助项目(2020JJ5198);江西省教育厅科学技术研究项目(GJJ203001,GJJ191277)。

摘　　要：对铸态AZ31镁合金进行预热温度为300~450℃、轧辊线速度为828 mm·s-1、单道次压下量为10%~80%的高应变速率(3.6~10.4 s-1)轧制,研究轧制过程中镁合金的显微组织及微裂纹演变机制。结果表明:孪生是变形初期主要的变形机制,孪晶的数量在变形初期迅速增加;随着压下量的增加,镁合金发生再结晶,孪晶数量增长趋势变缓;随着预热温度的升高,镁合金组织中的孪晶密度整体呈下降趋势;镁合金的再结晶方式以孪生诱导再结晶和晶界弓出再结晶为主,孪生、再结晶和微裂纹存在竞争关系;细晶区的裂纹由孔洞形成、长大和合并引起;孪生会诱发微裂纹,同时大量孪晶的产生又有利于抑制裂纹的扩展。The as-cast AZ31 magnesium alloy was high strain-rate(3.6-10.4 s-1)rolled at preheating temperatures of 300-450℃and rolling linear speed of 828 mm s-1 with single pass reductions of 10%-80%,and the microstructure and mechanism of microcrack evolution were investigated.The results show that twinning was the main deformation mechanism at early deformation stage,and the twin number sharply increased;with increasing rolling reduction,recrystallization occurred and the increase of twin number was gradually stable.Twin density in magnesium alloy microstructure decreased with increasing preheating temperature.Twinning induced recystallization and bulging recrystallization were the main recrystallization of magnesium alloy.The competition among twinning,recrystallization and microcrack existed.In fine grain area,the formation of crack was attributing to the initiation,growth and coalescence of holes.Twinning induced microcracks,while the formation of many twins could inhibit the crack propagation.

关 键 词：AZ31镁合金 高应变速率轧制 微裂纹 孪生 再结晶 

分 类 号：TG339[金属学及工艺—金属压力加工]