7003铝合金TIG焊焊接接头的组织与性能

采用显微硬度及电导率测试,剥落腐蚀及电化学腐蚀试验,光学显微镜(OM)及透射电镜(TEM),研究经ER5356焊丝钨极氩弧焊(TIG)的7003铝合金型材焊接接头各部分的微观组织与性能。结果表明:在离焊缝中心30 mm左右的热影响区位置形成硬度较低的软化区,这是由于η′(Mg Zn2)相的长大粗化;焊接接头的耐蚀性依次为焊缝区过时效区母材区淬火区,其原因是淬火区的晶界析出相连续分布,形成连续阳极腐蚀通道,增大了应力腐蚀及剥落腐蚀倾向,使得腐蚀性能很差;而过时效区和母材区的晶界析出相不连续,耐蚀性较好。

Microstructures and properties of TIG welded joint of 7003 aluminum alloy

The properties and microstructure of the different welded joint zone of 7003 aluminum alloy welded using 5356 welding wire by the method of TIG welding were researched by OM, TEM, vikers hardness and conduction test, exfloliation and electrochemical corrosion experiment. The results show that the heat affected zone, approximately 30 mm away from the centre of welding seam, is the soften zone as a result of η′(MgZn2) coarsening. The corrosion resistance of TIG welded joint are ,in order, Welded zone>Overaging zone>Base metal>Quenching zone. Because the precipitates from grain are continuous in quenching zone, which forms the continuous anode corrosion channel that increases the tendency of stress corrosion cracking and exfloliation corrosion, quenching zone has poor corrosion resistance. However,the precipitates from grain are discontinuous in overaging zone and base metal, which makes the overaging zone and base metal have a higher corrosion resistance.