Modeling of Mechanical Properties of Metastable Austenitic Cr–Mn–Ni Steels with TRIP Effect

Abstract

The mechanical properties of two metastable austenitic cast steels are examined by performing tensile tests in a temperature range of −70 to 300 °C. The 16‐6‐6 steel has an Ms temperature of −30 °C and an Md temperature of 100 °C. Athermal martensite formation down to −196 °C can be excluded for X3CrNiCuN17‐6‐4 steel. The Md temperature of X3CrNiCuN17‐6‐4 steel is 130 °C. The results obtained by a semiempirical thermodynamic‐mechanical calculation model are linked to experimental results from the tensile tests. The presented model combines chemical energy amounts from thermodynamic databases with mechanical energy amounts obtained by tensile tests with the aid of the conversion rule proposed by Patel and Cohen. Thermodynamic calculations are performed using the Thermo‐Calc software with the database TCFE10. As a result, the stress–temperature–transformation diagram showing the temperature dependence of proof stress, tensile strength, triggering stress for martensite formation, and the associated critical transformation temperatures (Ms, Md) is obtained. With the aid of the semiempirical thermodynamic‐mechanical model, it can be shown that the mechanical properties and critical temperatures of a metastable austenitic steel can be determined at very low experimental effort.