Research on stress corrosion cracking behavior of stainless steel bellows expansion joints used in GIS equipment

Abstract This article conducts metallographic structure, martensite content, Vickers hardness, and stress corrosion performance tests on two commonly used stainless steel bellows expansion joints with different materials and geometric parameters in the power grid. The material properties and stress corrosion sensitivity of 304 and 316 stainless steel bellows are compared. The results indicate that the martensite content is highest at the peak position and lowest at the trough position in the bellows. As the curvature radius of the bellows decreases, the martensite content increases at the same position. Under the same conditions, the content of deformed martensite in 304 stainless steel is much higher than that in 316 stainless steel. After soaking in boiling MgCl 2 solution for 7 days, the stress corrosion crack length of 304 stainless steel bellows is greater than that of 316 stainless steel. As the curvature radius of the ripple decreases, the crack length of 304 stainless steel bellows increases from 1.38 mm to 11.39 mm, while the crack length of 316 stainless steel bellows only increases from 0.32 mm to 7.32 mm.