预应变及时效处理对7A55铝合金残余应力及组织性能的影响  

Effect of pre-strain and aging treatment on residual stress,microstructure and properties of 7A55 aluminum alloy

作　　者：王淑慧[1] 杨春苗[1] 宋伟 盛光英[1] Wang Shuhui;Yang Chunmiao;Song Wei;Sheng Guangying(College of Engineering,Yantai Nanshan University,Yantai Shandong 265713,China;National Engineering Research Center for Plastic Working of Aluminum Alloys,Shandong Nanshan Aluminum Co.,Ltd.,Yantai Shandong 265700,China)

机构地区：[1]烟台南山学院工学院,山东烟台265713 [2]山东南山铝业股份有限公司国家铝合金压力加工工程技术研究中心,山东烟台265700

出　　处：《金属热处理》2020年第10期44-48,共5页Heat Treatment of Metals

基　　金：山东省自然科学基金(ZR2016EMQ11)。

摘　　要：研究了预应变和时效处理对7A55铝合金残余应力和组织演变的影响。利用透射电镜和EBSD观察了微观组织,XRD测试了残余应力,显微硬度计测试了维氏硬度。试验结果表明:固溶后的试样,表面为压应力,沿轧制方向为-75 MPa,横向-115 MPa。经不同的预应变后,表面残余应力逐渐降低,施加2%的预应变后基本消除。180℃的时效温度下,残余应力的消减速度显著高于100℃和140℃下。随预应变量的增大,显微硬度逐渐增大,经3%的预应变后增大为92 HV0.5,提高了27.8%。显微硬度随时效时间的增加先增高后降低,峰值出现在15 h,100、140和180℃下时效时分别达到135、143和162 HV0.5。100℃×15 h的峰值硬度下晶内主要析出亚稳η'相,与基体呈共格关系;140℃时晶内析出相尺寸变大,出现圆片状η'相,与基体呈半共格关系;180℃时出现了短棒状η'相,尺寸达到5~20 nm,位相差小于10°的小角度晶界占了80%以上。Effect of pre-strain and aging treatment on the residual stress,microstructure evolution and mechanical properties of 7A55 aluminum alloy were investigated by using TEM,EBSD,XRD and micro-hardness tester.The results indicate that the surface stress of the solution treated specimens is compressive,being-75 MPa and-115 MPa along rolling and transversal directions respectively.The residual stress decreases with the increase of pre-strain and almost being eliminated after 2%pre-strain.The subduction rate of residual stress for aging at 180℃is obviously quicker than that at 100℃and 140℃.The hardness increases with the increase of pre-strain,and after 3%pre-strain it increases to 92 HV0.5,i.e.by 27.8%.The hardness increases first and then decreases with the increases of aging time,and reaches 135,143 and 162 HV0.5 respectively when aging at 100,140 and 180℃for 15 h.When aging at 100℃for 15 h where the peak hardness is obtained,the metastableη'phase is mainly precipitated inside grains and has a coherent relation with the matrix.When aging at 140℃,the size of the intragranular precipitated phase increases,and semi-coherent disk-likeη'phase appears.While aging at 180℃,short rod-likeη'phase with a size of 5-20 nm appears,and the grain boundary with small angles(<10°)accounts for more than 80%.

关 键 词：7A55铝合金 残余应力 预应变 时效 

分 类 号：TG111.7[金属学及工艺—物理冶金]