Microstructure and stress corrosion behaviour of CMT welded AA6061 T-6 aluminium alloy joints

Abstract

Superior properties of AA6061 grade aluminium alloys are finding greater use in automotive, marine and aircraft applications due to its strength, weldability and high corrosion resistance. But it is highly susceptible to stress corrosion cracking owing to alter the phase composition and microstructure during welding process. In the present work, an experimental study of stress corrosion cracking is conducted on Cold Metal Transfer welded aluminium alloy joints using various heat input under constant stress intensity to understand the susceptibility of various zones to Stress Corrosion Cracking and the performance has been analysed using Tafel electrochemical technique. The result shows that the mechanism of cracking is established to be anodic mode with transgranular nature of crack propagation. In addition, a linear relationship is also inferred to predict the time to failure by extrapolating the rate of steady state elongation. The integrity of the dissimilar joints are analysed with the help of Optical Microscopy, SEM, EDAX and XRD sophisticated analytical techniques.