Evolution Behavior and Fracture Criterion of Carbides in D2 Cold‐Work Die Steel During Hot Working Process

Abstract

Investigating the fracture mechanisms of carbides is of paramount importance for optimizing hot working processes in die steels. This work establishes a comprehensive criterion equation to predict the behavior of carbide fracture in D2 cold‐work die steel during hot working process. High‐temperature laser confocal microscope is employed to prepare samples with varying solidification rates. Subsequently, these samples are subjected to a range of heating temperatures spanning from 1000 °C and 1100 °C. The samples are analyzed utilizing scanning electron microscopy energy spectrum analysis and X‐ray diffraction. The activation energy of M7C3 carbides is calculated through the utilization of kinetic equations and the Arrhenius law. Additionally, a criterion model for the fracture behavior of M7C3 carbides in D2 cold‐work die steel is established. The results reveal that thin hollow rod‐shaped carbide is easy to fracture. Moreover, the activation energy for phase transition of M7C3 carbides in D2 cold‐work die steels is determined to be 226.974 KJ mol−1. Furthermore, the fracture behavior of carbides in D2 cold‐work steel is found to be influenced by various factors such as heating temperature, deformation rate, and peak stress. Finally, the criterion model demonstrates substantial agreement with the experimental observations gathered, affirming its reliability and accuracy.