Corrosion behaviour of weld heat affected zone of aluminium alloy 7075

Abstract

The microstructure of the weld heat affected zone (HAZ) of alloy 7075 was simulated using a Gleeble system. The corrosion behaviour of several locations in the weld HAZ was investigated by means of differential scanning calorimetry, electrochemical measurement in 3.5 wt-%NaCl solution, and exfoliation corrosion tests. Different exfoliation corrosion morphologies for the base metal and weld HAZ were also observed. The corrosion morphology of the weld HAZ was mainly related to the degree of precipitation of eta' phase in the matrix. The HAZ in the region of the peak temperature 377 degrees C contained the most precipitation of eta phase, but no effect on corrosion morphology as a result of T6 post-weld heat treatment was observed. (C) 1997 The Institute of Materials.