Hot Deformation Behavior and Processing Map of Eutectoid Pearlite Rail Steel

Refining the austenite grain size is a key method for enhancing toughness without compromising strength in eutectoid pearlite rail steels. In this study, the effect of hot deformation parameters on the hot deformation behavior and refinement of prior austenite grains is investigated. The hot deformation behavior and microstructure of samples processed at deformation temperatures of 900, 950, 1000, 1050, 1100, 1150, and 1200 °C, strain rates of 0.01, 0.1, 1, and 5 s −1 , with a true strain of 0.9 are studied. A constitutive model and a processing map are developed to describe the deformation mechanism and microstructure evolution. The derived constitutive equation shows good agreement with experimental values, exhibiting a correlation coefficient ( M ) of 0.983 and an average absolute relative error (AARE) of 7.3%. Processing map indicates that the recommended thermomechanical parameters are temperature above 950 °C and a strain rate of 5 s −1 . The optimal austenite grain refinement effect can be achieved with 18.5 ± 8.9 μm when hot deformation is conducted at a temperature of 950 °C and a strain rate of 5 s −1 . These findings provide valuable insights in the optimization of hot deformation parameters of eutectoid pearlite rail steels.