Abstract
HYDROMAT project aims to build the knowledge base required for material innovations for hydrogen economy in Finland. The project is a collaboration between six industry partners, a research centre and a university. The project focuses on hydrogen solubility, diffusion, the effect of hydrogen on mechanical properties, and how the microstructure affects the aforementioned properties. The fracture toughness of three stainless steel grades is characterized: 1.4420, 1.4404, and 1.4435. In this study, the fracture toughness of 1.4420 (316+) was determined in gaseous hydrogen and nitrogen environment (100 bar) at room temperature using disk-shaped compact tension specimens. Testing was done following ASTM E1820 to determine the tearing resistance. The load rate and nominal a/W ratio are not strictly ASTM E1820 adherent. The testing in hydrogen gas was conducted as a constant displacement test performed in a double bellow based pneumatically powered Hybello with a miniature autoclave. The trends in fracture toughness will be explained through the microstructural characteristics of the material.