Work

Integrated experimental and 3D cellular automaton study of dynamic recrystallization mechanism in 42CrMo steel

Year: 2025

Type: article

Abstract: To systematically elucidate the dynamic recrystallisation (DRX) behavior of 42CrMo steel, single-pass isothermal-compression tests were conducted on a Gleeble-3800 simulator at deformation temperatures of 850-1150°C, strain rates of 0.001-1s-1 and true strains of 10-60%. Incorporating the Zener–Hollomon(Z) parameter, a DRX-critical model and calibrated flow-stress data, a physically based DRX-kinetics model was established that predicts the DRX volume fraction and average grain size with high accuracy (adjusted R2=0.98636). Coupling this model with microstructural observations clarified the softening mechanisms under different deformation conditions: discontinuous dynamic recrystallisation (DDRX), dominated by grain-boundary bulging and necklace structures, is the primary recrystallisation mechanism; the contribution of continuous dynamic recrystallisation (CDRX) is limited. Notably, the transformation microstructure also reflects DRX activity: at room temperature, martensite packet/block size is positively correlated with the prior-austenite grain size, and thermal activation promotes greater ordering in the transformation microstructure. By further coupling dislocation-density evolution, grain-boundary migration driving force and the three-dimensional Moore 26-neighbour rule, a three-dimensional cellular-automaton (3D CA) model was developed that faithfully reproduces spatially heterogeneous nucleation and growth. The simulated grain morphology and size distribution closely match experimental results, and the predicted average grain size agrees well with both experiment and the kinetics model, confirming the physical reliability of the 3D CA approach.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2025.08.121