The effect of strain rate and deformation temperature on the characteristics of isothermally hot compressed boron-alloyed steel

In the current work, the effects of deformation temperature and strain rate on microstructure and mechanical properties of a boron-alloyed steel after being isothermally compressed and subsequently quenched are investigated. The results indicate that at a constant strain rate, the hardness and martensite start temperature (Ms) normally increase as the deformation temperature increases. It is also observed that higher strain rates increase the hardness and flow stress, although a clear effect of strain rate on Ms is not observed. It is concluded that while increase of deformation temperature reduces the work hardening rate, the effects of strain rate on work hardening rate is intricate. Additionally, some models to deal with the work hardening rate variations as a function of temperature and strain rate are represented. Finally, the changes of flow stress, Ms temperature, hardness, and martensite volume fraction are compared in terms of the applied process routes: isothermal deformation followed by cooling, and simultaneous deformation and cooling processes.