Effect of friction stir lap weld and post weld heat treatment on corrosion behavior of dissimilar aluminum alloys

摘要

This study has been undertaken to evaluate the electrochemical behavior of friction stir lap welded V-95CHT1 and D19CHT plates and to study the effect of post weld heat treatment on the corrosion characteristics of the welded alloys. The corrosion characteristics were tested as per ASTM G-34 standard by immersion in EXCO solution and analyzing the corroded plates through optical imaging and scanning electron microscopic analysis. Cyclic polarization tests were also undertaken to validate the results of the immersion test. It was observed that friction stir lap weld had sensitized the V-95 plate with the heat-affected zone of the joint found most susceptible and weld nugget least susceptible to corrosion. Corrosion resistance of the welded plates was also found to be higher for those joints that were welded employing process parameters providing higher weld heat input. Post weld retrogression and re-aging heat treatment was also found to be beneficial in increasing the corrosion resistance of the alloy.