中等应变速率轧制制备多尺度混晶镁合金工艺及组织性能  

Medium-strain rate rolling process for multi-scale mixed-crystal magnesium alloy and its microstructure and mechanical property

作　　者：刘筱[1,2] 杨伟成 朱必武[1,2] 吴远志 唐昌平[1,2] 刘文辉[1,2] 宋宇峰 LIU Xiao;YANG Wei-cheng;ZHU Bi-wu;WU Yuan-zhi;TANG Chang-ping;LIU Wen-hui;SONG Yu-feng(Hunan Engineering Research Center of Forming Technology and Damage Resistance Evaluation for High Efficiency Light Alloy Components,Xiangtan 411201,China;Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province,Hunan University of Science and Technology,Xiangtan 411201,China;Research Institute of Automobile Parts Technology,Hunan Institute of Technology,Hengyang 421002,China)

机构地区：[1]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 [2]湖南科技大学高温耐磨材料及制备技术湖南省国防技术重点实验室,湘潭411201 [3]湖南工学院汽车零部件技术研究院,衡阳421002

出　　处：《中国有色金属学报》2023年第3期678-688,共11页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(52071139,51905166);湖南省教育厅优秀青年资助项目(21B0471);湖南省教育厅一般资助项目(20C0767)。

摘　　要：为了研究中等应变速率轧制下AZ31镁合金的组织演变过程和力学性能,获得同时提升强度和塑性的优良轧制工艺,对均匀化铸态AZ31镁合金进行平均应变速率分别为1.9 s^(-1)、4.8 s^(-1)和7.8 s^(-1),变形温度分别为370℃、410℃和460℃,下压量为75%的中等应变速率轧制,并构建嵌入式混晶结构的增塑模型。结果表明:中等应变速率轧制可制备多尺度混晶镁合金板材,410℃时可形成粗晶镶嵌在多层细晶中的嵌入式结构组织,在(410℃、4.8 s^(-1))时可形成细晶、中等晶粒和粗晶占比均匀并夹极少量超细晶和粗大晶粒的嵌入式结构组织;在410℃时轧制板材具有较好的强度和塑性匹配,尤其是在(410℃、4.8 s^(-1))时的轧制板材强度和塑性最为均衡,抗拉强度达279.4 MPa、伸长率达21.2%;相较于高应变速率轧制的细晶镁合金轧板,中等应变速率轧制的多尺度混晶组织镁合金轧板的强度明显提高,最大提高了19.7%,伸长率亦有提高;在410℃时轧制板材以韧性断裂为主,其他以韧-脆性断裂为主;微观组织为粗晶镶嵌在多层细晶中的嵌入式结构相比其他混晶结构具有更好的塑性。In order to study the microstructural evolution and mechanical properties of AZ31 magnesium alloy under medium-strain rate rolling,and to obtain the excellent rolling process which simultaneously improving the strength and plasticity,homogenized as-cast AZ31 magnesium alloy was rolled at medium strain rates of 1.9 s^(-1),4.8 s^(-1) and 7.8 s^(-1),at deformation temperatures of 370℃,410℃and 460℃with a reduction of 75%.Plasticization mechanism for embedded microstructure of coarse grain embedded in multiple fine grains was also established.The results show that medium-strain rate rolling could manufacture the multi-scale mixed-crystal magnesium alloy sheets.The sheets rolled at temperature of 410℃obtain embedded microstructure of coarse grain embedded in multiple fine grains.For the sheets rolled at 410℃with a average strain rate of 4.8 s−1,the embedded microstructure has uniform proportion of fine grain,medium size grain and coarse grain and small amount of ultra-fine grain and extra-coarse grain.The sheets rolled at temperature of 410℃have a good match of strength and plasticity,especially the sheets rolled at 410℃with an average strain rate of 4.8 s^(-1) which have the best balanced strength and plasticity.The tensile strength and elongation of rolled sheets at 410℃with an average strain rate of 4.8 s^(-1) are 279.4 MPa and 21.2%,respectively.The strength of the multi-scale microstructure magnesium alloy rolled at medium strain rate is obviously higher than that of the fine-grained magnesium alloy rolled at high strain rate and the maximum difference reaches to 19.7%.In most cases,the elongation of medium-strain rate rolling is also higher than that of high-strain rate rolling.The ductile fracture is the dominant fracture mechanism for rolled sheets at 410℃.For the other temperature conditions,ductile-brittle fracture is the main fracture mechanism.The embedded microstructure of coarse grain embedded in multiple fine grains has better plasticity compared with other mixed-crystal microstructur

关 键 词：AZ31镁合金 中等应变速率轧制 多尺度混晶 嵌入式结构 增强增塑 

分 类 号：TG146.2[一般工业技术—材料科学与工程]