Hot deformation behavior and processing map of low-alloy offshore steel

The hot deformation behavior of a low-alloy offshore steel was systematically investigated within the temperature range of 850–1150 °C and strain rate range of 0.01–10 s–1, via hot compression testing. The hot working equation, grain size model and recrystallization kinetic models of the steel were developed by fitting the experimental data. The results show that the decrease in Zener–Hollomon Z-parameter value (the increase in deformation temperature and the decrease in strain rate) is beneficial for the occurrence of dynamic recrystallization, and the grain size can be refined by increasing the Z-parameter value within the deformation range of dynamic recrystallization. However, when the Z-parameter value is higher than 3.43 × 1016, dynamic recrystallization will be difficult to occur within the range of experimental deformation conditions. Additionally, processing maps at different strains were constructed. According to the processing map and microstructural analysis, the optimal hot working conditions of the studied steel are within the temperature range of 1000–1100 °C and strain rate range of 0.1–1 s−1, and a complete recrystallization microstructure with fine homogeneous grains could be obtained.