Relationship between Stress-induced Martensite Phase Distribution and Nucleation Behavior of Main Crack in SUS304 Steel under SCC Condition

Abstract

The aim of the present study is to investigate the effect of stress-induced martensite phase on the nucleation of a main crack in SUS304 steel under Stress Corrosion Cracking （SCC） conditions. First, stress-induced martensite phase was produced on sensitized SUS304 steel by applying the pre-strain in liquid nitrogen. Then, the microstructure of martensite/austenite dual phase SUS304 steel specimens was investigated by means of the Electron Back Scatter Diffraction （EBSD） method. Second, an in-house SCC machine that can perform 3-point bending tests on specimens under corrosive conditions （0.1mass％K₂S₄O₆, ph＝2.0） at slow strain rates was developed. Then, a slow strain rate SCC test was conducted on the martensite/austenite dual phase SUS304 steel specimens. From the experimental results using EBSD analysis, microstructure and deformation behavior under slow strain rate SCC test, the effect of the stress-induced martensite phase on the nucleation of a main crack in SUS304 steel under SCC condition was discussed.