Hot Deformation Behavior of NM550 Wear-Resistant Steel

The flow stress, microstructure and softening mechanism of NM550 wear-resistant steel were investigated via hot compression test by using Gleeble-1500 thermal simulator in a temperature range from 800 to 1150 °C and strain rate range from 0.1 to 10s−1. With optical microscopy (OM), the effects of temperature, strain rate and true strain on the flow behavior and microstructure of the steel were discussed. The results show that the dynamic recrystallization occurs at higher temperature and lower strain rate. Hot deformation behavior of the steel specimens is sensitive to temperature and strain rate, while the strain rate affects the hot deformation behavior greatly. The apparent stress exponent and the apparent activation energy of the specimens are 7.395 and 389.611 kJ/mol, respectively. With the experimental data, the hot deformation constitutive equation and processing map of the NM550 wear-resistant steel are given. Finally, a combination of the constitutive equation and processing map provides a method for comprehensively investigating the hot deformation behavior of the steel under different conditions, and provides theoretical basis for the determination of rolling procedure in industrial production.