7075铝合金空心坯料旋转反挤压组织演变规律  

Microstructure evolution law of 7075 aluminum alloy hollow billet during rotary backward extrusion

作　　者：胡博文 王强[1] 杨勇彪[1] 陈佳星 张星[1] HU Bo-wen;WANG Qiang;YANG Yong-biao;CHEN Jia-xing;ZHANG Xing(School of Materials Science and Engineering,North University of China,Taiyuan 030051,China)

机构地区：[1]中北大学材料科学与工程学院,山西太原030051

出　　处：《塑性工程学报》2025年第4期90-96,共7页Journal of Plasticity Engineering

摘　　要：创新性地将空心坯料与旋转反挤压结合,利用Gleeble-3500热模拟试验机针对挤压态7075铝合金的微观组织演变规律进行研究。对变形后的合金进行金相分析和电子背散射衍射分析,探究其微观组织形貌和织构演化规律;对变形过程进行有限元模拟分析,揭示合金在变形过程中的应变场和速度场。结果表明,试样的大变形区可分为拐角区、底部上区和底部下区,3个区域内发生了不同程度的晶粒细化和动态再结晶。其中,底部上区形成了大量的细小等轴晶粒,再结晶率高达92.3%,且细晶层厚度达到3 mm以上,其平均晶粒尺寸和织构强度大幅减小。有限元模拟结果显示,大变形区的等效应变在10以上,该区域占试样总体积约1/5,等效应变最大高达31.3;在变形过程中,因旋转运动而形成的涡流速度梯度场是晶粒细化的主要原因。本研究解决了传统热变形铝合金难以形成等轴细晶及传统旋转反挤压大变形区狭小的普遍难题。The hollow billet was creatively combined with rotary backward extrusion(RBE),and the microstructure evolution law of asextruded 7075 aluminum alloy was studied by Gleeble-3500 thermal mechanical simulator.The metallographic analysis and electron backscatter diffraction analysis of the deformed alloy were carried out to investigate the microstructure morphology and texture evolution laws of the alloy.The finite element simulation analysis was carried out to reveal the strain field and velocity field of the alloy during the deformation process.The results show that the large deformation areas of the sample can be divided into corner area,upper-bottom area and lowerbottom area,in which different degrees of grain refinement and dynamic recrystallization(DRX)occur.Among them,a large number of fine equiaxed grains are formed at the upper-bottom area,the recrystallization rate is up to 92.3%,and the thickness of the fine grain layer reaches above 3 mm.The average grain size and the texture intensity are decreased greatly.The finite element simulation results show that the equivalent strain of the large deformation area is above 10,which accounts for about 1/5 of the total volume of the sample,and the maximum equivalent strain reaches 31.3.In the deformation process,the vortex velocity gradient field formed by rotational motion is the main reason for grain refinement.The common problems of forming equiaxed fine grains in hot deformed aluminum alloy and the narrow large deformation area by traditional rotary backward extrusion are solved.

关 键 词：7075铝合金 空心坯料 旋转反挤压 晶粒细化 织构演化 

分 类 号：TG146.2[一般工业技术—材料科学与工程]