Microstructure-based modelling the effect of spheroidized carbide morphology on the deformation compatibility of high carbon tool steel

The mechanical properties of high-carbon tool steels are strongly governed by the morphology of spheroidized carbides. In this study, the effects of three typical carbide morphologies—fine equiaxed, coarse equiaxed, and banded—on the deformation compatibility of C1.3CrTiX1 steel were systematically investigated by combining experiments with microstructure-based micromechanical simulations. Representative volume element (RVE) models based on actual microstructures were constructed, incorporating a dislocation density-based strain hardening model and the Gurson-Tvergaard-Needleman (GTN) damage model. The RVE-predicted results show that the equiaxed fine spheroidized carbides morphology exhibits the optimal strength-ductility synergy, with an average tensile strength of 832 MPa and an average uniform elongation of 18.95%, representing improvements of 13.2% and 8.6% over the banded spheroidized carbides morphology. It also shows the most uniform stress distribution, with the lowest strain localization factor (0.207) and the highest difference in plastic deformation (0.23). In contrast, the banded spheroidized carbides morphology exhibits severe stress concentration and the earliest softening. Moreover, the equiaxed fine spheroidized carbides morphology shows the largest transition strain ( ε 2 = 0.092), indicating enhanced strain hardening capacity. These findings reveal that a uniform dispersion of equiaxed fine spheroidized carbides promotes more homogeneous stress transfer and coordinated plastic deformation between phases, thereby enhancing mechanical performance. This study provides a quantitative framework for understanding the microstructure-property relationship and offers guidance for the microstructural design of high-carbon tool steels.