Abstract: The tensile, impacting, fracture toughness properties and the fracture surface of a high manganese austenitic steel are investigates from ambient temperature to 77 K. The results show that the relation between yield strength and temperature isσ0.2＝300＋1392.4exp（-0.0106T）. The 77K yield strength is 883 MPa, and the Kj0.05 value is about 232 MPa?m1/2. The cryogenic intergranular fracture is fully restricted. The 77K fracture surfaces exhibit a tough character composed of a huge quantitative of dimples and a little small qusi-cleavage facets. The results of X-Ray analysis show that the austenite of the steel is stable even under cryogenic deformation conditions.

Key words: Cryogenic property, High manganese austenitic steel