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

Abstract

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.

Friction Stir Welding of Dissimilar Aluminum Alloy Combinations: State-of-the-Art

“…Now the material movement is in an upward direction that is, from the bottom sheet to the top sheet, creating hook defects of various sizes. As expected, in addition to the rotation and welding speed, the placement of the BM affects the hook size as well [53,[72][73][74]. As it can be seen from Figure 6, the hook height is larger at the RS when the AA2024 is placed at the top, while it decreases when the AA7075 is placed as a top plate.…”

Studying the STA effects on aluminium alloy joints by friction welding

“…The HAZ, PDZ, and the Severely Deformed Zone (SDZ) are three separate zones that are created in aluminium alloys during friction welding [20][21][22]. However, due to variances in recrystallization temperature, dissimilar aluminium joints made using different solid-state welding techniques frequently generate weak welded joints [23][24][25][26][27]. The temperature of the welded specimens, particularly those close to the weld zone, is raised to the solutionizing temperature during FW due to frictional heat created during joint formation.…”