The AC corrosion and SCC mechanism of X80 pipeline steel in near-neutral pH solution
By Wan, Hongxia; Song, Dongdong; Cai, Yong; Du, Cuiwei
Published in Engineering Failure Analysis
2020
Abstract
This paper studied the mechanism of alternating current (AC) promoting corrosion and improving SCC susceptibility in near-neutral pH solution. It was found that AC can result in local corrosion. X80 steel generated some pitting under the effect of full wave AC for the anodic dissolution. Some acuity pitting generated due that hydrogen induced anodic dissolution for negative half-wave AC. However, X80 steel generated some larger radius pitting for the positive half wave AC which was related to anodic dissolution. AC can facilitate ion migration from the result of crack propagation experiment. The SCC susceptibility of X80 steel in NS4 near neutral pH solution was negative half wave AC > full wave AC > positive half wave AC. The finite element results showed that AC can promote hydrogen precipitation. AC promoted X80 steel corrosion for facilitating ion migration and improved SCC susceptibility for assisting hydrogen precipitation.