The influence of V and Mo on the hot deformation behavior of Fe-22Mn TWIP Steel

Abstract

In three types of high Mn TWIP steels with adding 0.5V and 0.5Mo base on 22Mn-0.4C, the influence of Mo and V on flow stress behavior, constitutive equations and microstructural evolution were investigated. For this purpose, the hot compression test were carried out different strain rates in 900 to 1200℃. The studied high Mn TWIP steels show same dependence of flow stress on deformation temperature and strain rate. The peak stress of 22Mn-0.5V and 22Mn-0.5V-0.5Mo TWIP steels were higher than 22Mn TWIP steels in almost deformation conditions, peak stress value of 22Mn-0.5V-0.5Mo TWIP steel was the highest. Material constants were determined using the Zener-Hollomon parameter and Sellars & McTegart equation and the activation energy was calculated. Calculated activation energy values for hot deformation were 420, 443 and 474 Jmol-1 for 22Mn, 22Mn-0.5V and 22Mn-0.5V-0.5Mo respectively. The effect of V and Mo on the microstructural evolution during the hot deformation seems to be different depending on the deformation conditions. At 900℃, it seems not significant. On the other hand, at 1100℃, V and Mo affect to dynamic recrystallization suppression and grain size refinement of 22Mn TWIP steels. As a result of the TEM confirmation, this is due to the precipitation effect at low temperature and the precipitation and solute drag effect at high temperature.