Study on Stress Corrosion Properties of Electron Beam Welded Joint of 30CrMnSiNi2A Steel

The stress corrosion of 28 mm thick 30CrMnSiNi2A ultra-high strength steel electron beam welded joints and base metal under different initial elastic stresses were investigated with 3.5wt% NaCl solution as corrosion medium at constant temperature of (35±1)℃.The stress corrosion morphology and stress corrosion cracking characteristics of the joint and the base metal were observed and analyzed by electron microscopy, and the stress corrosion rate of the joint and base metal was calculated and analyzed. The results show that when the initial elastic stresses are 75%, 80% and 85% of the yield strength, black corrosion products and corrosion products peeling off on the surface of the samples appear after 672 h of stress corrosion. The corrosion condition of samples has a certain positive correlation with the initial applied stress level.Under the same load level, the corrosion resistance of the joint is weaker than that of the base metal. The maximum crack widths of joint samples after stress corrosion cracking are 1.89, 3.54 and 6.84 μm, respectively. The average stress corrosion rates of joint samples are 1.361, 1.536 and 1.892 mm/a, respectively. The differences between the microstructure of base metal, heat affected zone and weld zone of the joint are slight, and all of them are tempered martensite.