焊后热处理对6061铝合金搅拌摩擦点焊接头腐蚀行为影响  

Effect of post weld heat treatment on corrosion behavior of 6061 aluminum alloy joint after friction stir spot welding

作　　者：韩磊 杨峰[1,2] 石端虎 夏晓雷[1] 陆兴华 HAN Lei;YANG Feng;SHI Duan-hu;XIA Xiao-lei;LU Xing-hua(School of Mechanical&Electrical Engineering,Xuzhou University of Technology,Xuzhou 221018,China;Jiangsu Key Laboratory of Large Engineering Equipment Defection and Control,Xuzhou Institute of Technology,Xuzhou 221018,China)

机构地区：[1]徐州工程学院机电工程学院,江苏徐州221018 [2]江苏省大型工程装备检测与控制重点实验室,江苏徐州221018

出　　处：《轻合金加工技术》2021年第2期65-70,共6页Light Alloy Fabrication Technology

基　　金：江苏省大学生创新创业计划项目(201911998064Y);徐州市应用基础研究计划项目(KH17005)资助;徐州工程学院校级培育项目(XKY2019110)。

摘　　要：采用回填式搅拌摩擦点焊(RFSSW)技术对2 mm厚6061铝合金板进行焊接,对焊接接头试样进行固溶、时效处理,并对焊核和母材在质量分数为3.5%NaCl的水溶液中的腐蚀电化学行为进行研究.结果表明:焊核区发生动态再结晶,晶粒呈细小的等轴状,热机影响区产生明显的塑性变形,晶粒发生了拉长和弯曲,热影响区的部分晶粒在热循环的作用下粗化;不同热处理条件下6061铝合金在NaCl水溶液中的电化学阻抗谱均由容抗弧和低频Warburg阻抗组成,随着时效时间的延长(8 h和16 h),晶界处析出第二相Mg2Si颗粒,化学成分不均匀,使得容抗弧半径减小,腐蚀电位降低,表现为阳极溶解和点蚀的特征.The back filling friction stir spot welding(RFSSW)technology was used to weld 2 mm thick 6061 aluminum alloy plate.After welding,the joint samples were treated by solid solution and aging.The corrosion electrochemical behavior of the weld nugget and base metal in 3.5%NaCl aqueous solution was studied.The results show that the dynamic recrystallization occurs in the nugget zone,the grains are fine equiaxed,obvious plastic deformation occurs in the thermo mechanical affected zone,the grains elongate and bend,and some grains in the HAZ coarsen under the action of thermal cycle.The electrochemical impedance spectra of 6061 aluminum alloy in NaCl aqueous solution under different heat treatment conditions consist of capacitive arc and low frequency Warburg impedance.With the prolongation of aging time(8 h and 16 h),the second phase Mg2Si particles precipitate at the grain boundary,and the chemical composition is not uniform,which makes the arc radius of capacitive reactance decrease and the corrosion potential decreases,showing the characteristics of anodic dissolution and pitting corrosion.

关 键 词：6061铝合金 搅拌摩擦点焊 腐蚀行为 热处理 

分 类 号：TG146.21[一般工业技术—材料科学与工程]