TIG氩弧辅助焊接对2519铝合金搅拌摩擦焊接头应力腐蚀开裂敏感性的影响  

Effect of TIG arc assisted welding on stress corrosion cracking susceptibility of friction stir welded joint of 2519 aluminum alloy

作　　者：易铁 刘胜胆[1,2,3] 方晨 江耿铎 戴轩轩 YI Tie;LIU Sheng-dan;FANG Chen;JIANG Geng-duo;DAI Xuan-xuan(School of Materials Science and Engineering,Central South University,Changsha 410083,China;National Key Laboratory of Science and Technology on High-strength Structural Materials,Central South University,Changsha 410083,China;Key Laboratory of Non-ferrous Metals Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China;School of Mechanical and Automotive Engineering,South China University of Technology,Guangzhou 510640,China)

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]中南大学轻质高强结构材料重点实验室,长沙410083 [3]中南大学有色金属材料科学与工程教育部重点实验室,长沙410083 [4]华南理工大学机械与汽车工程学院,广州510640

出　　处：《中国有色金属学报》2023年第10期3171-3184,共14页The Chinese Journal of Nonferrous Metals

摘　　要：采用常规搅拌摩擦焊(Friction stir welding,FSW)工艺和惰性气体钨极(Tungsten inert gas,TIG)氩弧辅助FSW工艺对2.5 mm厚2519-T87铝合金板材进行焊接,通过慢应变速率拉伸试验和电化学测试研究对比了两种接头的应力腐蚀开裂(SCC)敏感性。结果表明:引入TIG氩弧可降低焊接接头SCC敏感性,在3.5%(质量分数)NaCl溶液中,SCC敏感指数由1.47%降低至0.46%;当焊核区的腐蚀电流密度由2.177×10^(-6)A/cm^(2)降低至1.536×10^(-6)A/cm^(2)时,自腐蚀电位由-0.636 V提高至-0.616 V,焊核区的耐腐蚀性能也随之提高。结合金相显微镜、扫描电镜和扫描透射电镜对接头微观组织的方法,认为TIG氩弧辅助FSW工艺通过改善焊核区表层第二相粒子的大小和分布抑制了接头慢应变速率拉伸过程中腐蚀裂纹的萌生和扩展,从而降低了接头的SCC敏感性。The 2.5 mm thick 2519-T87 aluminum alloy sheets were welded by conventional friction stir welding(FSW)and tungsten inert gas(TIG)arc assisted FSW,respectively.The stress corrosion cracking(SCC)susceptibility of the two joints was investigated by slow strain rate tensile test and electrochemical test.The results show that the introduction of TIG arc can reduce the SCC susceptibility of the joint,and the SCC sensitivity index of the joint decreases from 1.47%to 0.46%in 3.5%NaCl solution,the corrosion current density in the nugget zone is reduced from 2.177×10^(−6)A/cm^(2)to 1.536×10^(−6)A/cm^(2),while the self-corrosion potential is increased from−0.636 V to−0.616 V,and the corrosion resistance of the nugget zone is improved.Based on the microstructure examination of the joints by using optical microscope,scanning electron microscope and scanning transmission electron microscope,it is considered that the TIG arc assisted FSW improve the size and distribution of second phase particles on the surface of the nugget zone,which inhibits the initiation and propagation of corrosion cracks during slow strain rate test and helps to reduce the SCC susceptibility of the joint.

关 键 词：2519铝合金 搅拌摩擦焊 TIG氩弧 应力腐蚀开裂 第二相粒子 

分 类 号：TF11.31[冶金工程—冶金物理化学]