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

Abstract

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 (HAZa) was more serious than that before laser repair (HAZb). The electrochemical impedance spectroscopy after different immersion corrosion time indicated that the HAZa and HAZb had similar corrosion potentials. However, the pitting corrosion resistance of HAZa was lower than that of HAZb 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.

Electrochemical Corrosion Behavior of MIG-Welded 7N01-T4 Aluminum Alloy by ER5356 and ER5087 Welding Wires

“…A 7N01 aluminum alloy welded joint experienced the rapid hot and cold process, the local microstructure changed complex, the precipitated phase produced unbalanced dissolution and precipitation behavior, and redistributed in the boundary and grain boundary, resulting in the non-uniformity structure of a welded joint. Thus, the corrosion resistance decreased [ 10 , 11 ]. Moreover, 7N01 aluminum alloy has corrosion sensitivity in humid and chlorine environments [ 12 , 13 , 14 ].…”