热压缩变形终了温度对7050铝合金显微组织的影响

张新明，韩建鹏，刘胜胆，黄星星，刘军

(中南大学 材料科学与工程学院，湖南 长沙，410083)

摘 要：采用Gleeble1500热模拟机对7050铝合金进行多道次热压缩试验，热压缩开始温度为430 ℃，经过7道次热压缩变形，终了温度分别控制在300，340，370，400和430 ℃。采用光学显微镜、扫描电镜和透射电镜观察合金在不同终了温度热压缩变形后及固溶时效后的显微组织。研究结果表明：随着终了温度的升高，各相同道次的流变应力逐渐下降；热压缩变形后合金组织中第二相粒子逐渐减少；尺寸较小的亚晶逐渐演变成晶界平直的晶粒；当终了温度较低时，合金变形后储存大量的变形能，固溶时效后出现大量的再结晶组织；随着终了温度的升高，变形过程中动态、静态软化消耗的变形能增加，固溶时效后再结晶组织逐渐减少。

关键词：7050铝合金；终了温度；显微组织；第二相粒子

Effect of finishing temperature on microstructure of 7050 aluminum alloy during hot-compression deformation

ZHANG Xin-ming, HAN Jian-peng, LIU Sheng-dan, HUANG Xing-xing, LIU Jun

(School of Materials Science and Engineering, Central South University, Changsha 410083, China)

Abstract:Hot compression of 7050 aluminum alloy was carried out on Gleeble 1500 thermal simulator. Through seven-pass hot-compression deformation, the finishing temperatures were controlled to 300, 340, 370, 400 and 430 ℃ respectively at initial hot-compression temperature 430 ℃. The microstructures of the alloy after hot-compression deformation and solution-aging treatment were investigated by the means of optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that with the increase of finishing temperature, the flow stress of the same pass is gradually decreased and the second phase particles are reduced, while the small-size subgrains are gradually grown to the grains with straight boundary. At low finishing temperature, where more deformation energy is stored after deformation, there is a large number of recrystallization structure after solution-aging treatment. Dynamic and static softening consumes more deformation energy during the hot deformation with the increase of finishing temperature and the recrystallization structure is gradually reduced after solution-aging treatment.

Key words:7050 aluminum alloy; finishing temperature; microstructure; the second phase particle