Investigation on thermal rheological behavior and processing map of 30CrMnSiNi2A ultra-strength steel

To investigate the effects of forming parameters on the thermal rheological behavior and microstructure evolution of a 30CrMnSiNi2A ultra-strength steel during thermal plastic deformation, thermal compression tests were carried out under different forming temperatures and strain rates. The microstructure of 30CrMnSiNi2A steel suffered from thermal compression and rapid cooling was composed of lath-shaped martensite, plate-shaped martensite, and retained austenite. The sizes, morphologies, and proportions of those ferrous phases in compressed 30CrMnSiNi2A steel specimens were affected significantly by forming temperatures and strain rates. The effects of forming temperature and strain rate on austenitization and dynamic recrystallization of 30CrMnSiNi2A steel were investigated. Based on the experimental results, the constitutive equation and processing map of 30CrMnSiNi2A steel were established. The unsafe areas of 30CrMnSiNi2A steel were not only distributed in the regions with lower temperature and lower strain rate, but also distributed in the regions with higher temperature and higher strain rate. When thermal processing was conducted at 1050 °C with a strain rate of 0.1 s−1, ideal thermal plastic formability was exhibited by 30CrMnSiNi2A steel.