焊后时效热处理对6063铝合金CMT焊接接头组织性能的影响

Effect of post-weld aging treatment on microstructure and properties of CMT welded joints of 6063 aluminum alloy

采用5183铝合金焊丝为填充材料对6063铝合金板材进行协同脉冲冷金属过渡焊(CMT),并对焊接接头分别进行530℃1 h+170℃(4 h,8 h,12 h)的焊后固溶+时效热处理。以焊接接头为研究对象,重点对比分析了时效热处理时间(4 h,8 h,12 h)对焊缝和热影响区的显微组织、显微硬度及力学性能的影响。结果表明:经焊后热处理,焊缝中长条状的β-Mg2Si转变为圆点状或短棒状β-Mg2Si,焊缝组织无明显变化;而对于热影响区而言,随着时效时间的增加,细小的纳米尺寸强化相β″相逐渐增加,热影响区硬度明显提高,导致焊缝成为焊接接头的软化区。因此,经焊接后固溶+时效热处理,焊接接头的断裂位置由热影响区移至焊缝处,焊接接头的强度提高了约51%、达到220 N/mm2。

Cold metal transfer mix+synchropulse welding process(CMT)was performed on 6063 aluminum alloy plates with 5183 aluminum alloy weld wire as the filler.The welded joints were heat treated with solid solution at 530℃ for 1 h and ageing at 170℃ for4 h,8 h and 12 h respectively.The effects of aging time(4 h,8 h and 12 h)on microstructure,microhardness,and mechanical properties of weld seams(WS)and heat-affected zones(HAZ)were compared and analyzed with the welded joints as the research objectives.The results show that stripe-shapedβ-Mg_(2) Si is transformed to dot-shaped or short rod-shapedβ-Mg_(2)Si and WS structure doesn't show significant change.With aging time increasing,the fine Nano-sized strengthening phaseβ"increases gradually in HAZ.The micro-hardness of HAZ increases significantly,and the weld seam becomes the soft zone.Therefore,after solid solution and aging heat treatment after welding,the fracture position of welded joint moves from HAZ to WS,and the strength of welded joint is increased by 51%to 220 N/mm^(2).