(1. 湖南科技大學(xué) 機電工程學(xué)院，湘潭 411201；
2. 湖南科技大學(xué) 材料科學(xué)與工程學(xué)院，湘潭 411201；
3. 湖南科技大學(xué) 湖南省新能源汽車產(chǎn)學(xué)研海智創(chuàng)新中心，湘潭 411201；
4. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400044)
摘 要: 為了改善傳統(tǒng)熱軋AZ31鎂合金板材的微觀組織，提升其綜合力學(xué)性能，本文采用二道次變路徑軋制與深冷處理相結(jié)合的方法，研究了深冷處理對二道次不同路徑軋制下AZ31鎂合金微觀組織和力學(xué)性能的影響。結(jié)果表明：經(jīng)深冷處理后，AZ31鎂合金軋制板材晶粒平均尺寸顯著細化至7.8 μm，織構(gòu)強度能夠由16弱化至9.5，合金組織中有孿晶生成，少量的第二相在晶界處析出。此外，二道次同一路徑軋制下的板材經(jīng)過20 min深冷處理，塑性得到極大改善，斷裂伸長率高達23.2%；與傳統(tǒng)軋制工藝相比，二道次交叉路徑軋制板材經(jīng)20 min的深冷處理，其硬度、抗拉強度分別由68 HV和246 MPa提升至75.8 HV、268 MPa。
關(guān)鍵字: 鎂合金；二道次變路徑軋制；深冷處理；微觀組織；力學(xué)性能
（1. College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
2. College of Materials Science and Engineering, Hunan University of Science and Technology, Xiangtan 411201, China;
3. Hunan Provincial Overseas-wisdom Innovation Center of New Energy Vehicle in Industrial-academic-research Cooperation, Hunan University of Science and Technology, Xiangtan 411201, China;
4. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China）
Abstract:In order to improve the microstructure and mechanical properties of traditional hot-rolled AZ31 magnesium alloy sheets, the effects of cryogenic treatment on microstructure and mechanical properties of AZ31 magnesium alloy sheets were studied by using the method of two-pass variable paths rolling combined with cryogenic treatment. The results show that, after cryogenic treatment, the grain size of rolled AZ31 magnesium alloy sheet is refined to 7.8 μm dramatically and the texture is also weakened from 16 to 9.5, meanwhile, the second phase precipitates along the grain boundary and produces small portions of twins after cryogenic treatment. In addition, after 20 min cryogenic treatment, the ductility of AZ31 magnesium alloy sheet is greatly intensified, and the fracture elongation is as high as 23.2%. Compared with the traditional rolling process, the strength and hardness of two-pass cross-path rolling combined with 20-min cryogenic treatment are significantly strengthened, and the hardness and tensile strength increases from 68 HV and 246 MPa to 75.8 HV and 268 MPa, respectively.
Key words: magnesium alloy; two-pass variable paths rolling; cryogenic treatment; microstructure; mechanical properties
