Abstract: The hot deformation behavior of 50Mn18Cr4V nonmagnetic high manganese steel within the strain rates of 01-10 s-1 and deformation temperatures of 900-1 100 ℃ was studied by high temperature uniaxial compression tests. The results show that straininduced precipitation of VC particles has an important effect on the hot deformation behavior of the tested steel. When the deformation temperature is 900-1 000 ℃ and the strain rate is 5 s-1， the precipitation of VC is insufficient and then the suppression of dynamic recrystallization is weakened， compared with that at the strain rate of 1 s-1. It is better for the total reduction to be accomplished in relatively higher temperature regions with an appropriate strain rate. As the deformation temperature decreases below 950 ℃， the hot plasticity is poor so that the thermal cracking prefers to occur at lower strain rates and the tendency of flow instability increases at higher strain rates. Accordingly， the optimized strain rate is 5 s-1 during hot working process. Furthermore， the activation energy of the tested steel is 7769 kJ/mol for hot deformation. The mathematic model of deformation resistance at high temperature was also established.

Key words: 50Mn18Cr4V, nonmagnetic high manganese steel, hot deformation, dynamic recrystallization, deformation resistance model