en گروه مکانیکی و شکل دادن Mechanical Performance and Formability of Materials Research Paper Research Paper In this paper a constitutive equation was considered for the isothermal hot compression test of the Mn-Ni-Cr alloy. The hot compression test was performed in the strain rate range of 0.001-0.1 s^-1 and deformation temperature was varied from 700 to 900 °C. A considerable reduction in flow stress was observed regardless of the strain rate when temperature was increased from 700 to 750 °C. DTA and XRD evaluation revealed that the removal of Mn₃Cr phase and formation of the single solid solution phase were the reason for the flow stress reduction. At the low deformation temperature (700°C) and the high strain rate (0.1 s^-1), a partially recrystallized microstructure was observed; this was such that with increasing the temperature and decreasing the strain rate, a recrystallized microstructure was completed. Also, the relationships between flow stress, strain rate and deformation temperature were addressed by the Zener-Holloman parameter in the exponent type with the hot deformation activation energy of 301.07 KJ/mol. Finally, the constitutive equation was proposed for predicting the flow stress at various strain rates and temperatures. ,Hot deformation,Constitutive equation,Zener-Holloman,Mn-Ni-Cr alloy 102 108 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-2324-1&slc_lang=en&sid=1 M. Sadeghi mohsen.sadeghi.m@gmail.com 180031947532846009665 180031947532846009665 No Materials Engineering Department, Malek Ashtar University of Technology, Shahin Shahr, Iran M. Hadi morteza.hadi@gmail.com 180031947532846009666 180031947532846009666 Yes Department of Materials Science and Engineering, Golpayegan University of Technology, Golpayegan, Iran O. Bayat obayat@iust.ac.ir 180031947532846009667 180031947532846009667 No Department of Materials science and Engineering, Hamedan University of Technology, Hamedan, Iran H. Karimi hadi_karimi2009@yahoo.com 180031947532846009668 180031947532846009668 No Materials Engineering Department, Malek Ashtar University of Technology, Shahin Shahr, Iran.