Stress Corrosion Cracking Test Using Notched Round-Bar Specimen of Type 310S Steel in 25% MgCl₂ Solution at 80°C

Abstract

Stress corrosion cracking test of Type 310S steel was conducted potentiostatically in 25% MgCl₂ solution at 80°C. Notched round-bar specimen made it possible to study the stress corrosion crack initiation at the base of notch as a corroding crevice under an application of fracture mechanics. Cracking occurred at the potential range from -380 to -340mV (SCE) and when stress intensity, K_I, was over K_ISCC≅7.5kg·mm^-3/2. In the region II where K_I was larger than 10kg·mm^-3/2 crack growth l_II, did not depend on K_I and was insensitive to changes in electrode potentials. The lower limit of the potential range for cracking is the potential just more noble than the repassivation potential for crevice, E_R.CREV, and the upper is regarded to correspond to that where l_II is equal to the dissolution rate at the crevice-bottom.