Mechanical properties of 32Mn-7Cr-0.6Mo-0.3N austenitic steel for cryogenic applications

The tensile, impact, and fracture toughness tests from ambient temperature to 77 K were carried out on 32Mn-7Cr-0.6Mo-0.3N austenitic steel. The fracture surfaces and the phase constitution were analyzed using scanning electron microscopy and x-ray diffraction. The results show that the relation between yield strength and temperature is σ0.2 · 300 + 1392.4 exp (−0.0106T). The 77 K yield strength is 883 MPa · m1/2 and the K J0.05 value is about 236 MPa · m1/2. The cryogenic intergranular fracture is fully suppressed. The 77 K fracture surfaces exhibit a tough character composed of many dimples and few small quasi-cleavage facets. The results of x-ray analysis show that the austenite phase of the steel is stable even under cryogenic deformation conditions.