6061-T6铝合金DP-MIG焊轧复合成形接头组织与力学性能  

Microstructure and mechanical properties of DP-MIG welding-rolling composite forming joints of 6061-T6 aluminum alloy

作　　者：宋刚[1] 董孝南 程继文 王泽力 刘黎明[1] SONG Gang;DONG Xiaonan;CHENG Jiwen;WANG Zeli;LIU Liming(Key Laboratory of Advanced Connectivity Technology of Liaoning Province,Dalian University of Technology,Dalian,116024,China)

机构地区：[1]大连理工大学,辽宁省先进连接技术重点实验室,大连116024

出　　处：《焊接学报》2023年第4期1-6,29,I0003,共8页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(U1960111);中央高校基本科研业务费专项资金资助项目(DUT21LAB133)。

摘　　要：为解决6061-T6铝合金焊后热影响区软化导致力学性能下降的问题,基于焊接接头余高大变形强化过时效软化区的思想,采用双轧辊系统对6061-T6薄板铝合金直流双脉冲熔化极气体保护焊(DC double pulse metal inert gas welding,DP-MIG焊)接头进行同步双面轧制,并分析了焊轧复合成形接头组织与力学性能.结果表明,焊缝晶粒受到竖直方向的轧制力发生大塑性变形,内部气孔消失,焊缝区域变宽,邻近焊缝的热影响区受到来自焊缝的挤压力发生协同宏观变形,远离焊缝的过时效软化区组织受到来自焊缝处的压应力,从沿垂直焊缝方向产生部分协同形变强化;接头的硬度明显提升,过时效软化区的硬度由60~70 HV提升至80~90 HV,过时效软化区的拉伸性能也有所提升,当焊接速度为800 mm/min时,抗拉强度最佳可达到母材的83.6%,相较于焊接接头提升19.4%,进而实现了对过时效软化区的强化效果.To solve the problem of degrading of mechanical properties of as welded 6061-T6 aluminum alloy joint caused by softening of the heat-affected zone,this study applied a double-roller system to perform simultaneous double-sided rolling on 6061-T6 thin aluminum alloy DC double pulse metal inert gas(DP-MIG)welded joints,based on the idea of utilizing welding residual height and large deformation to strengthen the over-aging softened zone.The microstructure and mechanical properties of the welding-rolling composite forming joints were analyzed.The results are as follows:the weld grain is subjected to large plastic deformation by the vertical rolling force;The internal pores disappear,thus the weld area widens.The heat-affected zone adjacent to the weld is subjected to co-macro deformation by the extrusion force from the weld,and the over-aging softened zone far from the weld is subjected to compressive stress from the weld,resulting in partial co-deformation strengthening along the vertical weld direction.The overall hardness of the joints is significantly improved with the hardness of the over-aging softened zone,which increased from 60−70 HV to 80−90 HV.The tensile properties of the over-aging softened zone are improved.When the welding speed is 800 mm/min,the best tensile strength can reach 83.6%of that of the base metal,19.4%higher than that of the welded joint,which is a notable improvement to the over-aging softened zone.

关 键 词：铝合金 热影响区软化 直流双脉冲熔化极气体保护焊 焊轧复合成形 

分 类 号：TG441.8[金属学及工艺—焊接]