Effect of Heat Treatment on Stress Corrosion Cracking Behavior and Electrochemical Characteristic of Welded Ti-6Al- 4V Alloy during Slow Strain Rate Test

摘要

Local rapid induction heating is used as a post weld heat treatment for a welded Ti-6Al-4V alloy. Thewelded sample is heat treated at different temperatures. The microstructure and corrosion behavior ofthe welded sample before and after the post weld heat treatment are investigated. Electrochemicalimpedance spectroscopy (EIS) measurements under slow strain rate test (SSRT) are performed in aLiCl-methanol solution. The results demonstrate that the microstructure in fusion zone evolves fromacicular martensite phase in the as-welded sample to lathy phase and transformational phase inthe heat treated samples. The lathy phase decreases and the transformational phase increases withthe increase of the heat treatment temperature in the fusion zone. The mechanical properties andcorrosion resistance of the welded samples are significantly improved after the heat treatment andgradually increase with the increase of the heat treatment temperature, which indicate that the postweld heat treatment effectively reduces the susceptibility of the welded Ti-6Al-4V alloy to stresscorrosion cracking.