焊接工艺方法对6061-T6铝合金焊接接头疲劳性能的影响

通过对6061铝合金MIG焊接头和TIG焊接头在对应的加载应力条件下疲劳寿命的测定,对比分析了两种工艺方法对铝合金焊接接头疲劳性能的影响。结果表明,在加载应力低于焊接接头静载力学性能的90%时,焊接接头的疲劳寿命均能满足需求背景的需要(100000次不破坏)。同样载荷条件下,MIG焊接头的疲劳性能优于TIG焊接头,尤其是在高应力条件下,MIG焊接头的优势更为明显。焊接接头显微组织分析表明,MIG焊接头比TIG焊接头具有更为细小的晶粒和焊接热影响区,有效地提高了接头的滑移形变抗力,抑制了循环滑移带的形成和开裂,从而提高接头的疲劳性能。疲劳断口分析显示,试件的表面缺陷(疏松、气孔、夹杂等)及机械损伤是疲劳裂纹主要的策源地。

Effect of welding processes on fatigue properties of 6061-T6 aluminum welded joints

The effect of welding processes (MIG and TIG) on fatigue properties of 6061-T6 aluminum welded joints are analyzed based on fatigue testing. The results shows that the fatigue life of two kinds of joints can settle for the requests of applied objects when loads are under 90% of the tensile strength of welded joints. And the fatigue properties of MIG welded joints are better than those of TIG welded joints, especially under higher loading conditions. Fracture morphologies and microstructures of joints are comparatively fine in the MIG welds with high fatigue life opposed to the TIG welds having comparatively low fatigue life. Fracture morphologies also shows that the fatigue fracture occurred from porosities, inclusions, incomplete joint penetrations and other weld defects and nicks, ect.