Hydrogen Embrittlement Properties of Austenitic Stainless Steel Type 316L Welded Joint

Abstract

The global promotion of hydrogen refueling stations for fuel cell vehicles (FCV) is driven by the vision of achieving a Hydrogen Society. In Japan, a design pressure of 70 MPa has become the standard to enhance the cruise distance of FCV. However, this higher gas pressure increases the risk of hydrogen leakage from mechanical joints. Consequently, the infrastructure industry emphasizes the need to understand the hydrogen compatibility of welding joints to ensure the safer and more cost-effective operation of these facilities. This paper presents the results of slow strain rate tensile (SSRT) tests conducted in a high-pressure gaseous hydrogen environment to assess hydrogen embrittlement in austenitic stainless joints. During specimen preparation, U-grooves were machined at the edges of the plates, which were then butted together to form filler welded joints using Gas Tungsten Arc Welding (GTAW) with commercially available AWS ER 316L filler wire (high Ni-equivalent) under two different weld heat inputs (9.9 and 36.0 kJ/cm). The welded joints exhibited a low susceptibility to hydrogen embrittlement, despite the increase in the amount of crystallized delta ferrite in the weld metal with a decrease in the weld input. Based on the results, we conclude that the Type 316L welded joint with AWS ER 316L filler is suitable for various components in hydrogen refueling stations with the applied welding conditions. This valuable insight contributes to realizing safer and more reliable hydrogen refueling facilities while also reducing maintenance costs.