2A12铝合金交流CMT焊接工艺对接头微观组织及性能的影响

Effect of AC CMT welding technology on microstructure and properties of 2A12 aluminum alloy

为探明交流CMT焊接方法对1.5mm薄板2A12铝合金焊缝成形、微观组织及力学性能的影响规律,采用单因素控制对比试验对交流CMT焊缝成形、微观组织及力学性能进行了分析,试验研究了焊接电流及EP/EN两个特征参数对焊缝成形、微观组织及力学性的影响规律。结果表明:随着焊接电流的增加焊缝的熔深变深,熔宽变宽,鱼鳞纹形貌逐渐消失,微观组织在焊缝区及热影响区逐渐变大,强化相析出相逐渐减少,力学性能先上升后下降。随着EP/EN的增大,焊缝的熔深变深,熔宽变宽,鱼鳞纹形貌变化不明显,焊缝区微观组织为等轴晶且逐渐细化,而热影响区晶粒则变得粗大,力学性能逐渐下降。焊接接头出现软化现象,抗拉强度仅为母材的65%左右,热影响区是焊接接头的薄弱区域。当I=63A,EP/EN=12/10,v=70cm/min时,力学性能最好,抗拉强度是311MPa。本实验为2A12铝合金熔焊提供工艺支持。

In order to explore the influence of AC CMT welding method on appearance of weld,microstructure and mechanical properties of 1.5mm thin 2A12 aluminum alloy,the single factor control contrast test was used to analyze the appearance of weld,microstructure and mechanical properties of AC CMT 2A12 aluminum alloy joint.The effects of welding current and EP/EN characteristics on appearance of weld,microstructure and mechanical properties were studied.The results show that with the increase of welding current,the throat depth and weld width become deeper and wider,the morphology of fish scale gradually disappears,the microstructure in the weld zone and the heat affected zone gradually increases,the precipitation phase gradually decreases,and the mechanical properties firstly increase and then decrease.With the increase of EP/EN,the weld depth and weld width become deeper and wider,the morphology of fish-scale grain does not change obviously.The microstructure of weld zone is equiaxed and refined gradually,while the grain of heat affected zone is coarser,the mechanical properties decrease gradually.The welding joint softens,the tensile strength is only about 65% of the base metal,and the heat affected zone is the weak area of the welding joint.When I=63A,EP/EN=12/10,V=70cm/min,the mechanical properties are the best,and the tensile strength is 311MPa.This experiment provides process support for 2A12 fusion welding.