Mechanical behavior and microstructure evolution of spheroidized-annealed GCr15 bearing steel under dynamic loading

In this study, the intrinsic correlation between dynamic mechanical behavior and microstructural evolution of spheroidized-annealed GCr15 bearing steel with a ferrite-carbide dual-phase structure has been investigated under high strain rates (3000–7000 s −1 ) and wide temperature ranges (20–650 °C). To more accurately characterize the dynamic mechanical response，the conventional TANH-Johnson-Cook (TANH-JC) constitutive model is optimized by incorporating the actual strain rate and the softening effect arising from adiabatic temperature rise observed in Split Hopkinson Pressure Bar (SHPB) experiments. This modification significantly improves the model's prediction accuracy. Furthermore, the coupling mechanisms among deformation parameters, dynamic recrystallization of ferrite, and carbide evolution are elucidated using multi-scale characterization techniques. Continuous dynamic recrystallization (CDRX) is identified as the primary grain refinement mechanism in the ferrite matrix, supplemented by particle-stimulated nucleation dynamic recrystallization (PSNDRX). The evolution of carbides is governed by the synergistic interaction of temperature and strain rate. The atomic diffusion capacity is enhanced with increased temperature, while numerous additional rapid diffusion pathways are introduced through its coupling with plastic deformation. These factors promote the dissolution of small carbides and the coarsening of large carbides. When thermal effects dominate, significant carbide dissolution weakens the Zener pinning effect, leading to coarsening of recrystallized grains. These microstructural evolution characteristics collectively govern the macroscopic mechanical response through three primary strengthening mechanisms: grain boundary strengthening, dislocation strengthening, and precipitation strengthening. This study provides practical engineering guidance for optimizing the turning process of material in subsequent machining operations. • The intrinsic connection between microstructure and mechanical behavior of spheroidized-annealed GCr15 bearing steel with dual-phase materials under dynamic loading were first revealed. • The refinement of ferrite grains is driven by the synergistic effect of CDRX and PSNDRX mechanism under high strain rates and wide temperature ranges. • The effects of temperature and strain rate on carbide dissolution and coarsening were elucidated, and the interaction mechanism with ferrite recrystallization was further revealed. • Prediction accuracy was significantly improved by incorporating the effect of actual strain rate in the TANH-JC model.