- A number of workers have reported that unstable stainless steels undergo significant reduction in ductility and moderate decreases in the ultimate tensile strength in slow strain rate tensile tests, carried out at room temperature in gaseous hydrogen environment (1-3). The previous work indicates that the hydrogen must be present during stressing for embrittlement to occur. Exposure of specimens to the gas followed by testing in air, did not lead to embrittlement (2). In the present work, exposure of the 316L stainless steel to hydrogen gas and subsequent tensile testing revealed significant changes in the plastic flow curves and the fracture mode. An attempt was made to correlate between the tensile properties and the mode of fracture.