Austenite phase stability: reflection on low temperature materials

Phase stability in metastable austenitic stainless steel has been a major issue, in focussing on the appropriate low temperature materials properties. In the current study, attention has been given to the interaction of hydrogen on the fracture resistance capacity response of AISI 304L and 316L, at low temperatures. Pre-strained specimens followed with high fugacity hydrogen charging, were tested at the temperature range 95K - 295K, to establish the standard monotonic mechanical properties. In addition, microscopic observation, metallographic and fractographic studies were performed with emphasis on fracture morphology and modes, cracking sequence, and crack depth. Finally, X-Ray diffraction was applied to detect deformation and hydrogen induced phases. Based on the present results, the degradation of mechanical response is analyzed from stress-strain curves, with correlation to fracture modes and cracking phenomena.