摘要
采用TIG焊制备2219铝合金焊件,并结合金相(OM)、扫描电镜(SEM)、投射电镜(TEM)、浸泡实验和电化学实验等分析测试方法,研究了2219铝合金锻件TIG焊接头的组织演变和腐蚀行为。结果表明:焊缝组织呈树枝状等轴晶,细小均匀;局部腐蚀原电池形成倾向减弱,电位正移,耐蚀性能最好;母材区由于残余结晶相和晶界时效析出相连续析出,腐蚀发生在残余结晶相周围贫铜区和晶界处,且晶界作为腐蚀通道加速阳极溶解速率,导致母材区在腐蚀溶液中最先腐蚀;过时效区因析出相在晶界上的断续分布,晶界电位将正移,有利于腐蚀性能的提高;淬火区存在大量含Cu过饱和固溶体,且未见无沉淀析出带,是抗腐蚀性能较过时效区进一步提高的原因。由于残余结晶相、基体、析出相和晶界结构的共同作用导致合金接头耐蚀性存在差异,依次为焊缝区>淬火区>过时效区>母材区。
2219 aluminum alloy weldment was prepared by the method of TIG welding.The microstructure evolution and corrosion behavior of 2219 aluminum alloy weldment joint was investigated by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM),immersion test and electroche-mical corrosion experiment.The results show that the microstructure in the welded zone is dendrites,fine and homogeneous with equiaxed grains.When the corrosion happens,the corrosion potential moves to positive direction and the corrosion resistance increases.The co-existence of residual crystallization phase and continuous grain boundary precipitates in the base metal area,results in the corrosion of the copper poor area around the residual crystalline phase and the grain boundary.Meanwhile,the continuous intergranular phases play a role as channel for electron transfer in the corrosion process,which could accelerate the anodic dissolution rate.All above mentioned factors leaded to the worst corrosion resistance of base metal area.The grain boundary precipitates have discontinuous distribution in the over-aging zone,promoting corrosion potential of grain boundary to shift to a more positive value,which is beneficial to the improvement of corrosion resistance.Lots of Cu-containing supersaturated solid solution and disappearance of precipitate free zones make the corrosion resistance of the quenching zone is superior to that of the over-aging zone.The corrosion resistance of TIG welding joint is different due to the combined action of residual crystalline phases,αAl-matrix,precipitates and grain boundary,which are in the order of welded zone>quenching zone>over-aging zone>base metal.
作者
徐道芬
陈康华
邢军
陈送义
李晓谦
XU Daofen;CHEN Kanghua;XING Jun;CHEN Songyi;LI Xiaoqian(Light Alloy Research Institute,Central South University,Changsha 410083,Hunan,China;School of Mechanical Engineering,Guilin University of Aerospace Technology,Guilin 541004,Guangxi,China;Guangxi Colleges and Universities Key Laboratory of Robot&Welding,Guilin University of Aerospace Technology,Guilin 541004,Guangxi,China;State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,Hunan,China)
出处
《华南理工大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2020年第3期116-125,共10页
Journal of South China University of Technology(Natural Science Edition)
基金
国家重点研发计划项目(2016YFB0300801)
国家自然科学基金委员会-中国航天科技集团公司航天先进制造技术研究联合基金资助项目(U1637601)
国家自然科学基金重大科研仪器设备研制专项(51327902)
广西高校机器人与焊接重点实验室开放课题基金资助项目(JQR2018ZR02)
广西教育厅科研项目(KY2015ZD141)。
关键词
2219铝合金锻件
焊接接头
组织演变
腐蚀行为
2219 aluminum alloy forging
welded joints
microstructure evolution
corrosion behavior
