Effect of laser repairing on corrosion behaviour of metal–inert gas welding joint of 7N01 aluminium alloy

The heat affected zone (HAZ) on the metal-inert gas (MIG) welding joint of 7N01 aluminium alloy was repaired by multipass narrow gap laser welding. The Y-X direction precracked three-point bending sample was used in the alternate immersion test. The morphology of specimen surfaces demonstrated that the exfoliation corrosion in the HAZ after laser repair (HAZ(a)) was more serious than that before laser repair (HAZ(b)). The electrochemical impedance spectroscopy after different immersion corrosion time indicated that the HAZ(a) and HAZ(b) had similar corrosion potentials. However, the pitting corrosion resistance of HAZ(a) was lower than that of HAZ(b) at the beginning of exfoliation corrosion. The stress corrosion crack (SCC) of 7N01P-T4 aluminium alloy displayed a multicrack source and an intergranular crack propagated along the rolling grain boundary under the test condition. An unusual method was taken to measure the length of SCC. The results showed that laser repairing did not weaken the stress corrosion resistance of the original joint.