Investigation of the effect of hot compression on microstructure and mechanical properties of Mn-25Ni-5Cr alloy

In this study, the hot-working behavior of Mn-25Ni-5Cr alloy was studied using hot compression tests at the temperatures of 850 ˚C, 900 ˚C, 950 ˚C and 1000 ˚C and the strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1 and 1 s-1 to a true strain level of 0.7. The results of flow curves showed that the flow stress decreases with increasing temperature and decreasing strain rate. Regarding the shape of flow curves, peak appearance represents the dynamic recrystallization. The peak stress and strain of flow curves appeared in fewer strains at high temperatures and strain rates. The microstructural evolution is mainly controlled by dynamic recrystallization. The presence of evolving boundaries around the recrystallized grains also indicates the occurrence of continuous dynamic recrystallization during hot working. In closer scrutiny of microstructure and fasciology, using by SEM microscope equipped with EDS detector, in addition to the background phase, second phase consisting of manganese, nickel and chromium was identified. The constants of n, α and β were determined using constitutive, power and exponential equations at 0.3 strain. According to the constitutive equation of the hyperbolic sinus, the amount of activation energy in the strain of 0.3 is 394.6258 kJ/mol.