Abstract: The impact fracture characters of high Mn austenitic steel with N are analyzed and the fracture mechanism is discussed by means of cryogenic temperature impact test and fractography. The transgranular facet is a kind of charactic fracture topography of high Mn austenitic steel with N. Due to the influence of alloy elements and the test temperature, the cleavage strength SOT is less than the shearing strengthτ k, and therefore the transgranular brittle fracture is produced. The fracture plane is the {111}γ or twin boundary. While τ k and SOT are closely the same, various mixed fracture topographes are formed. More N content in austenitic steel results in the transgranular brittle fracture.

Key words: Austenitic steel, Fracture topography, Transgranular brittle fracture