Abstract
Hydrogen embrittlement (HE) is a complex phenomenon that affects a lot of metals characterized by a degradation of the mechanical properties. UNS S31603 with a minimum yield strength (YS) of 25 ksi (170 MPa), is frequently used for hydrogen applications due to its low susceptibility to HE, which is promoted by a high austenite stability. However, its use is limited when higher strength is required. Here, nitrogen-strengthened (UNS S20910), CrMnN and high interstitial (HIS) austenitic stainless steels in solution-annealed condition displaying YS higher than 55 ksi (380 MPa) could be part of a solution. The strength of these steels can be further increased by strain-hardening to YS higher than 758 MPa (110 ksi).
This paper discusses the susceptibility of high strength UNS S20910, CrMnN and HIS to hydrogen embrittlement. Characterization of microstructure, mechanical properties, and HE was performed for the materials in solution-annealed and strain-hardened condition. Slow strain rate tests (SSRT) were carried out in hydrogen atmosphere at 10 MPa (100 bar) and room temperature. UNS S20910 and CrMnN with a YS higher than 850 MPa (123 ksi) are resistant against hydrogen embrittlement showing a ductile fracture mode. On the other hand, HIS-steels are susceptible to HE with a loss in ductility.