Effect of TIG-dressing on fatigue properties of 7N01 aluminium alloy welded joint

TIG-dressing of 7N01 aluminium alloy welded joint was carried out by shielded metal arc welding.The fatigue properties and microhardness of specimens were tested before and after TIG-dressing,and the fractography was analyzed with SEM and the composition in defect zone was examined with XRD.Experimental results show that TIG-dressing slightly reduced the stress concentration on the weld toe,however,TIG-dressing could also bring additional weld defects which would initiate fatigue crack.The reheating by TIG-dressing could soften the welded joint and degrade the resistance to fatigue crack propagation.Consequently,the fatigue life of welded joint after TIG-dressing slightly decreased.Therefore,it had no feasibility to improve the fatigue properties of 7N01 high strength aluminium alloy welded joint by TIG-dressing.