热处理对2219铝合金双频复合脉冲TIG焊接头组织演变及力学性能影响  

Effect of heat treatment on microstructure evolution and mechanical properties of 2219 aluminum alloy joint as fabricated by double-pulsed TIG welding

作　　者：尹玉环 曾才有 高焓 张铁民 齐铂金[2] 从保强[2] YIN Yuhuan;ZENG Caiyou;GAO Han;ZHANG Tiemin;QI Bojin;CONG Baoqiang(Shanghai Aerospace Equipments Manufacturing Co.,Ltd.,Shanghai,200240,China;Beihang University,Beijing,100191,China;Beijing Spacecrafts Co.,Ltd.,Beijing,100190,China)

机构地区：[1]上海航天设备制造总厂有限公司,上海200240 [2]北京航空航天大学,北京100191 [3]北京卫星制造厂有限公司,北京100190

出　　处：《焊接学报》2022年第4期42-49,I0005,共9页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(52075022);上海市自然科学基金项目(19ZR1423300)。

摘　　要：系统对比研究了直接时效处理和固溶时效处理对2219-T6铝合金双频复合脉冲TIG焊接头强化的影响.分析了焊后热处理工艺对α-Al晶粒、共晶组织及时效析出行为的影响,讨论了接头组织不均匀性对塑性变形行为的影响机制.结果表明,直接时效处理对α-Al晶粒和共晶组织影响较小,在焊缝区引入低密度粗大θ’-Al_(2)Cu析出相,对接头强化效果有限,且对塑性有损害;而固溶时效处理导致α-Al晶粒粗化、共晶组织含量降低且尺寸细化,在焊缝区引入高密度细小θ’’-Al3Cu析出相(平均直径22 nm),并显著提升接头强度和塑性,使得接头强度系数达到0.84,断后伸长率升高至7.0%.固溶时效处理导致的接头强塑化源于焊缝区内高密度纳米θ’’-Al3Cu相所产生的析出强化效应,使得接头强度匹配更加均衡,促进了接头均匀塑性变形,并提升了接头抗拉强度.In the present study,the effects of typical postwelding heat treatments,including direct aging treatment(AT)and solution treatment + aging treatment(STAT),on the strengthening effect of 2219-T6 joint fabricated by doublepulsed variable polarity tungsten inert gas welding were investigated comparatively.The evolution of α-Al grain,eutectic structure and precipitations during different post-welding heat treatments were investigated.Moreover,the influence mechanism of microstructure heterogeneity on the plastic deformation behavior of the joint was discussed.Obtained results show that AT affected slightly α-Al grain and eutectic structure,and introduced low-density coarse θ’-Al_(2)Cu precipitation into the welding seam.AT has a limited strengthening effect on 2219-T6 aluminum alloy joint and a damage to plasticity.While,STAT lead to coarsening of α-Al grain and decrease in the content and size of eutectic structure.Meanwhile,a high-density fine θ’’-Al_(2)Cu particles with a mean diameter of 22 nm was introduced by STAT into the welding seam.STAT can significantly improve the strength and plasticity of the joint,make the strength coefficient of the joint reach up to 0.84 and the elongation increase to 7.0%.The strengthening and plasticizing effect of the joint caused by STAT result from a more homogeneous strength matching among each region of the joint,due to the significant precipitation strengthening of nano θ’’ particles in welding seam.That promoted a more uniform overall plastic deformation and lead to the increase in ultimate tensile strength.

关 键 词：热处理 铝合金 脉冲焊接 显微组织 力学性能 

分 类 号：TG456.7[金属学及工艺—焊接]