6061铝合金激光-MIG复合焊接头的组织与力学性能

• 作 者: 范聪 杨尚磊 段晨风 朱敏琪 白易山
• 出 处: 中南大学学报（英文版）
• 发表日期: 2022年3期
• 关键词: aluminum alloy laser-MIG hybrid welding fatigue property microstructure mechanic

本文采用激光-MIG复合焊接技术对3 mm的6061铝合金板材进行焊接.在实验的基础上,确定了最佳的焊接工艺参数,保证了熔透焊接.采用光学显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)对焊接接头的微观组织、拉伸和疲劳断口形貌以及表面疲劳损伤进行分析.结果表明,焊接接头中存在两种主要析出相,一种是晶界长的富Si沉淀相,另一种是晶内富Cu沉淀相.拉伸试验结果表明,接头的抗拉强度为224 MPa,仅为母材的70.2％.通过对拉伸断口的分析,发现母材与接头拉伸韧窝的形成有很大差异.在应力率为0.1的拉-拉疲劳试验中,母材和焊接接头的条件疲劳极限分别为101.9和54.4 MPa.通过对比不同应力幅下焊接接头的疲劳断口,发现导致接头断裂的主要因素是气孔.通过对孔隙缺陷的进一步分析,发现孔隙中微裂纹的扩展方式有穿晶和沿晶两种,并存在二者混合扩展方式.“,”In this paper, 3 mm 6061 aluminum alloy sheets were welded by laser MIG hybrid welding. Based on the experiment, the best welding parameters were determined to ensure the penetration welding. The detailed microstructure, tensile and fatigue fracture morphology and surface fatigue damage of the welded joints were analyzed by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that there are two main kinds of precipitates, one is the long Si rich precipitates at the grain boundaries, the other is the intragranular Cu rich precipitates. The tensile test results show that the tensile strength of the joint is 224 MPa, which is only 70.2％ of the base metal. Through the analysis of tensile fracture, there are great differences in the formation of tensile dimple. In the tensile-tensile fatigue test with a stress rate of 0.1, the conditional fatigue limits of base metal and welded joint are 101.9 MPa and 54.4 MPa, respectively. By comparing the fatigue fracture of the welded joints under different stress amplitudes, it was found that the main factor leading to the fracture of the joint is porosity. Through further analysis of the pore defects, it was found that there are transgranular and intergranular propagation ways of microcracks in the pores, and the mixed propagation way was also found.