Stress corrosion cracking behavior of laser-MIG hybrid welded 7B05-T5 aluminum alloy

Abstract

The stress corrosion cracking behaviour of laser MIG-hybrid welded 7B05-T5 aluminum alloy joint was studied by using pre-cracked wedge-open loading (WOL) specimens immersed in 3.5 %NaCl solution. The critical stress intensity factor for stress corrosion cracking (KISCC), and the cracks propagation rate (da/dt) were determined. The stress corrosion cracking propagation mechanism of welded joints was analyzed by fracture scanning and microstructure analysis. The results illustrated that both the base metal (BM) and the heat-affected zone (HAZ) were susceptible to stress corrosion cracking (SCC), but the weld zone (WZ) was not sensitive to SCC. The fracture mode of the aluminum alloy in SCC appeared the intergranular and transgranular mixed fracture. It was considered that the coaction of anodic dissolution and hydrogen embritt-lement contributed to SCC.