Effect of heat-treatment on high-pressure hydrogen gas embrittlement of austenitic stainless steels

Abstract

Testing equipment for materials under high-pressure hydrogen of 120 MPa at the temperature range of room temperature up to 393 K has been developed. The pressure vessel was designed to enable the measurement of actual tensile load on a specimen by an external load cell without the influence of axial load due to high pressure in the vessel and the friction between the O-rings and the pull rod. The hydrogen gas embrittlement (HGE) of austenitic stainless steels of SUS304, 316, 316L, 316LN and 310S was examined in 70 and 105 MPa hydrogen and argon by slow strain rate technique (SSRT) test at room temperature. Hydrogen showed a marked effect on the tensile properties of SUS304 and 316 stainless steel, a minimal effect on those of SUS316LN, and no effect on those of SUS316L and 310S. The HGE of sensitized SUS304, 316 and 316LN was larger than that of solution-an-nealed ones. It was observed that hydrogen caused brittle transgranular fracture along the strain-induced martensite in solution-annealed steels, and intergranular fracture in sensitized steels respectively. © 2008 The Japan Institute of Metals.