Effect of surface hydrogen contents on hydrogen embrittlement properties of stainless steels

Abstract

Susceptibility to hydrogen embrittlement (HE) of austenitic stainless steels were investigated by Slow Strain Rate Testing (SSRT), both in gaseous hydrogen environment pressurized at 45 MPa and under electrochemical cathodic charging conditions. Test results were discussed based on estimated surface hydrogen contents of the unstressed steels into which hydrogen was charged under the same test conditions as SSRT. HE susceptibility of the steels in both gaseous hydrogen environments and electrochemical cathodic charging depended upon estimated surface hydrogen contents. Minimal of surface hydrogen content for HE were less than 10 ppm for 304L steel, and 100 ppm for 316L, respectively. The threshold value for 316L exceeded the content of hydrogen naturally absorbed from 45 MPa gaseous hydrogen environments, indicating that 316L has a sufficient resistance to hydrogen embrittlement in gaseous hydrogen environment pressurized at 45 MPa.