Effect of chloride ion concentration on stress corrosion cracking and electrochemical corrosion of high manganese steel

Abstract

Abstract The effect of Cl− concentration on stress corrosion cracking (SCC) susceptibility of high manganese steel was investigated by slow strain rate tensile (SSRT) test, electrochemical test, and immersion test in different NaCl concentration solutions. The results show that the SCC susceptibility of the test steel first increases and then decreases with the increase in Cl− concentration. When the NaCl concentration was 10.5%, the SCC susceptibility was the highest, and the fracture showed river-like transgranular quasi-cleavage morphology, obvious tearing ridge, and strong brittle fracture characteristics. The corrosion current density of the sample first increases and then decreases with the increase in Cl− concentration in the corrosive medium. The corrosion electrochemical reaction and corrosion product layer play a synergistic role in SCC in low concentration Cl− medium. The enrichment of alloying element compounds in the corrosion layer leads to the local acidification below the corrosion layer, which promotes the anodic dissolution (AD) and forms pitting corrosion on the substrate surface. When the Cl− concentration is high, the local AD and hydrogen embrittlement (HE) caused by the dissolved oxygen will be weakened, and SCC susceptibility is reduced.