Application of Electrochemical Noise to Investigate Role of Microstructural Evolution on Inhibiting Stress Corrosion Cracking of Ti–6Al–4V Weldment

Abstract

Using the electrochemical noise method, this paper studies the effect of microstructure of weld seam on the stress corrosion cracking behavior of Ti–6Al–4V alloy weldment. Local rapid induction heating can significantly change the microstructure, and the acicular α′ martensite phase in the weld seam is decomposed into lathy α phase and transformed β phase. The higher heat temperature leads to more transformed β phase and less lathy α phase. The mechanical properties and stress corrosion cracking sensitivity during the slow strain rate tensile test are significantly affected by the microstructure of weld seam, which are improved with the decomposition of acicular α′ martensite and decrease of lathy α phase content combined with increase of transformed β phase content. Compared with the non-treated sample, the induction heating enhances the corrosion resistance of the sample and delays the occurrence time of localized corrosion during the slow strain rate tensile test. The higher corrosion resistance and the later occurrence time of localized corrosion are caused by the higher induction heating temperature. The microstructural evolution of the weldment significantly inhibits the stress corrosion cracking process.