Effect of PriorAustenite Grain Size onTensile Properties of (Ferrite+Cr2N) Lamellar Eutectoid-Structured Steel

摘要

Fe-Cr-N system Ni-free high nitrogen austenitic steel easily decomposes to lamellar eutectoid structure by isothermal heat treatment in (ferrite+Cr2N) two phase region. Authors had reported that the morphology of (ferrite+Cr2N) lamellar eutectoid structure is similar to that of pearlite in Fe-C alloys, which is characterized by colony structure, where direction of Cr2N nitride is identical, and block structure, where the crystallographic orientation of ferrite is identical(1). However, (ferrite +Cr2N) eutectoid steel tends to have lower ductility than pearlitic steel, and thus, tensile testing of this steel resulted in the brittle fracture without necking deformation(2). Since grain refinement generally improves ductility and toughness of steel, the effect of prior austenite grain size on tensile properties was investigated in this study using Fe-25%Cr-1%N alloy with different prior austenite grain size.