Effects of electrochemical corrosion on retrogressed and different reaged friction stir welded AA7075-AA6082 dissimilar welds

The research is primarily to study the microstructure, tensile and electrochemical corrosion behaviour of friction stir welded AA7075-T651-AA6082-T6 dissimilar welds, subjected to retrogression and reaging at 280⁰C for 5 min followed by aging at 110⁰Cfor 1 , 5 , 10 and 24 h respectively. The AA7075-AA6082 welds were made using optimum parameters such as feed rate 80 mm/min, tool rotation speed 980 rpm, and tilt angle 2o. The alloys of 100 × 50 × 6mm³ plates were welded with a conical tapered tool pin profile. Further, the welds were scanned for potentiodynamic polarisation with a 3.5 percentNaCl solution. Optical metallographic (OM) images were revealed to determine morphology andcorrelate with the measured corrosion rate. Here, the dissimilar friction stir weld AA7075-AA6082-aged for 5 h had an 'Ultimate tensile strength' (UTS) of 269.73N/mm2 due to coherent precipitates. Moreover, at 24 h, the lower tensile strength of 226.06 N/mm2 was observed, due to coarser precipitates across the AA7075-AA6082 weld cross-section. Due to over-aged coarse precipitates, the corrosion rate of 6082BM and weld metal had increased to 5.110e + 003mpy and 1.010e + 003mpy. Under other aged conditions, the corrosion rate was decreased below 0.001mpy.