Compatibility of cold drawn and heat treated austenitic stainless steel (316L) tube for green hydrogen applications

Abstract

Abstract

Abstract Austenitic stainless steels are widely used for hydrogen handling and transport due to their corrosion resistance and generally low susceptibility to hydrogen-assisted cracking. However, soft zones introduced to material during fabrication and repairs or in services remains a concern for tube-based hydrogen distribution systems. In this work, a 316L (14,404) cold drawn 1/2″ (12.7 mm outer diameter) tube with wall thickness 1 mm was investigated in the cold drawn state and after weld-thermal cycle simulation by joule heating (heat-treated) state. Tube sections were machined into hollow tensile specimens and tested by slow strain rate tensile (SSRT) loading at the nominal strain rates of 1E-4 s −1 , 1E-5 s −1 and 1E-6 s −1 under the in situ gaseous hydrogen and in argon as reference (150 bar, room temperature). Additional precharging conditions were performed in the ex situ gaseous hydrogen autoclave precharging (1000 bar, 150 °C, 21 days) before SSRT. Tensile properties (ultimate tensile strength, yield strength, elongation, and reduction of area) were quantified, and hydrogen effects were expressed using degradation indices. The SSRT results at all strain rates indicate enhancement of strength and ductility in both the cold-drawn and heat-treated states. Across the investigated conditions, fracture surfaces showed predominantly ductile microvoid coalescence fracture. These findings contribute to the understanding of the compatibility of 316L tubing for hydrogen applications under the investigated conditions while highlighting the importance of processing state and hydrogen interactions.