自然时效耦合预拉伸提升Al-Zn-Mg-Cu合金力学性能和腐蚀抗力  

Improving mechanical properties and corrosion resistance of Al⁃Zn⁃Mg⁃Cu alloy through natural aging coupled pre⁃stretching

作　　者：董泰励 李昉 陈庚 张晨 郭子龙 陈康华 陈送义[1,2] Dong Taili;Li Fang;Chen Geng;Zhang Chen;Guo Zilong;Chen Kanghua;Chen Songyi(Light Alloy Research Institute,Central South University,Changsha Hunan 410083,China;Collaborative Innovation Center of Advanced Nonferrous Structural Materials and Manufacturing,Central South University,Changsha Hunan 410083,China;Powder Metallurgy Research Institute,Central South University,Changsha Hunan 410083,China)

机构地区：[1]中南大学轻合金研究院,湖南长沙410083 [2]中南大学有色金属先进结构材料与制造协同创新中心,湖南长沙410083 [3]中南大学粉末冶金研究院,湖南长沙410083

出　　处：《金属热处理》2024年第4期104-110,共7页Heat Treatment of Metals

基　　金：国家重点研发计划(2021YFF0600504);湖南省自然科学基金(2023JJ30668)。

摘　　要：采用透射电镜(TEM)、扫描电镜(SEM)、拉伸试验、剥落腐蚀和晶间腐蚀等手段研究了不同自然时效时间耦合3%预拉伸对Al-Zn-Mg-Cu合金时效析出组织、力学和耐腐蚀性能的影响。结果表明,自然时效4天耦合3%预拉伸能调控后续时效过程中晶界附近的时效析出行为,显著地减小晶界附近无析出带宽度。其原因是自然时效4天后晶界附近无析出带存在大量溶质原子,再经3%预拉伸在晶界附近无析出带产生大量位错,促进后续时效过程析出相形核,从而减小晶界附近无析出带。窄的晶界附近无析出带能避免位错的塞积,抑制孔洞长大和裂纹扩展,显著提高合金的伸长率。同时在阳极溶解过程中,减少被腐蚀的阳极暴露面积,从而降低腐蚀速率,增加剥落腐蚀和晶间腐蚀抗力。自然时效4天耦合3%预拉伸工艺获得的抗拉强度、伸长率和最大晶间腐蚀深度分别为562 MPa、17.23%和191.4μm。Effect of natural aging time coupled with 3%pre⁃stretching on the aging precipitation microstructure,mechanical properties and corrosion resistance of Al⁃Zn⁃Mg⁃Cu alloy was studied by using transmission electron microscope(TEM),scanning electron microscope(SEM),tensile testing,exfoliation corrosion and intergranular corrosion.The results show that natural aging for 4 days coupled with 3%pre⁃stretching can regulate the aging precipitation behavior near grain boundaries during subsequent aging processes,significantly reducing the width of the precipitation free zone near grain boundaries.The reason is that the precipitation free zone containing amount of solution atoms is formed after natural aging for 4 days,followed by the subsequent 3%pre⁃stretching to induce a large number of dislocations in precipitation free zone,promoting the subsequent aging process to precipitate phase nucleation and reducing the width of the precipitation free zone.The elongation of the Al⁃Zn⁃Mg⁃Cu alloy is significantly improved due to the narrow precipitation free zones near grain boundaries can avoid the accumulation of dislocations,suppress pore growth and crack propagation.Meanwhile,the exposed area of the corroded anode is reduced during the anodic dissolution process,which can reduce the corrosion rate and increase the resistance of exfoliation corrosion and intergranular corrosion.The tensile strength,elongation,and maximum intergranular corrosion depth obtained by coupling natural aging for 4 days process with 3%pre⁃stretching are 562 MPa,17.23%and 191.4μm,respectively.

关 键 词：形变热处理 AL-ZN-MG-CU合金 无析出带 拉伸性能 耐腐蚀性能 

分 类 号：TG146[一般工业技术—材料科学与工程]