热变形对喷射成形7055铝合金挤压板微观组织的影响  

Effect of hot deformation on the microstructure of spray-formed 7055 aluminum alloy extruded plate

作　　者：蔺晓敏 吴晓东 曹玲飞 唐松柏 白敏 LIN Xiao-min;WU Xiao-dong;CAO Ling-fei;TANG Song-bai;BAI Min(International Joint Laboratory for Light Alloys(Ministry of Education),College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Shenyang National Laboratory for Materials Science,Chongqing University,Chongqing 400044,China)

机构地区：[1]International Joint Laboratory for Light Alloys(Ministry of Education),College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China [2]Shenyang National Laboratory for Materials Science,Chongqing University,Chongqing 400044,China

出　　处：《Journal of Central South University》2023年第12期3950-3963,共14页中南大学学报（英文版）

基　　金：Project(CSTB2022TIAD-KPX0073)supported by the Chongqing Key Project for Technological Innovation and Application,China;Project(CSTB2022NSCQ-LZX0002)supported by the Natural Science Foundation of Chongqing,China;Projects(2022-Z03,2020-ZD02)supported by the Opening Project of State Key Laboratory for Advanced Metals and Materials,China。

摘　　要：通过单道次热压缩实验和Deform有限元模拟相结合的方法,研究了喷射成形7055铝合金挤压板在300~450℃、0.01~25 s^(−1)范围内的热变形行为。结合热压缩实验获得的热加工图、Deform模拟热压缩过程获得的真实应变和损伤分布以及计算出的几何必需位错(GND)和形变储能,综合分析了合金在热变形过程中的微观组织演变。结果表明:安全加工区位于低应变速率区,其中高温低应变速率区域(400~450℃,0.01~1.0 s^(−1))为其最适宜热加工条件,在该区域热加工后,功率耗散系数(η值)最大,损伤值最低。失稳区集中在高应变速率区域(即1.0~25 s^(−1)区间内),该区域具有最大的损伤值并易于开裂。此外,针对因挤压板在失稳区热加工后表层和中心样品在后续470℃/2 h固溶处理过程中出现的粗晶和晶粒异常长大问题,设计了在热变形前进行慢速升温长时热处理的工艺方案,并讨论了相关的再结晶行为。该热处理制度可以有效降低挤压板中的残余位错密度和形变储能,且在慢速升温过程中析出的大量Al3Zr粒子具有钉扎晶界、降低界面迁移率和阻碍位错运动的作用,从而抑制了热变形后板材在固溶处理过程中的静态再结晶。The hot deformation behavior of spray-formed 7055 aluminum alloy extruded plate was studied under conditions of 300−450℃and 0.01−25 s^(−1)through a combination of Gleeble hot compression experiments and Deform-3D software simulations.The processing maps,simulation results,and calculation of residual dislocation density and stored energy were used to understand the microstructure evolution of the alloy.The results show that the optimum hot working conditions for the alloy lies within the high-temperature and low-strain rate region(400−450℃,0.01−1.0 s^(−1)),where the power dissipation coefficientηis the highest and the damage is the lowest.The unstable domain is concentrated in the high strain rate region(1.0−25 s^(−1)),which has the highest damage and is prone to cracking.Moreover,a slow heating and long duration heat-treatment prior to hot deformation was designed to solve the problem of formation of coarse grains and abnormal grain growth after solution treatment.This heat treatment can effectively reduce the residual dislocation density and stored energy,and promote the precipitation of Al3Zr particles to hinder dislocation movement and pin grain boundaries,thereby inhibiting the static recrystallization during solution treatments.

关 键 词：喷射成形7055铝合金 热变形行为 Deform-3D软件 损伤值 粗晶组织 

分 类 号：TG146.21[一般工业技术—材料科学与工程]