Development of New Material Testing Apparatus in 230 MPa Hydrogen and Evaluation of Hydrogen Gas Embrittlement of Metals

Abstract

A new materials testing apparatus using an external loading system in 230 MPa hydrogen at room temperature was developed. The apparatus consisted of a pressure vessel with a loading device for the slow strain rate technique (SSRT). The elimination of the axial load due to high pressure acting on the pull rod was achieved by the pressure balance method. The apparatus was designed to measure the actual load on the specimen with an external load cell irrespective of the axial load caused by high pressure and friction at the sliding seals. The hydrogen gas embrittlement (HGE) of austenitic stainless steels, SUS304, SUS316, SUS316LN, SUS316L and SUS310S of the Japanese Industrial Standard (JIS), and an iron-based superalloy, SUH660 JIS, and a nickel-based superalloy, Hastelloy C22, was evaluated by conducting SSRT tests in 210 MPa hydrogen using the apparatus at room temperature. The following was observed: SUS304, moderate HGE in stage II; SUS316, moderate HGE in stage III; SUS316LN, light HGE in stage III; SUS316L, light HGE in FS; SUS310S, undetectable HGE; SUH660, light HGE in stage III; and Hastelloy C22, heavy HGE in stage II. The HGE of the materials was also discussed.