CARMEN OTILIA RUSANESCU, COSMIN JINESCU, MARIN RUSANESCU, MARIA CRISTIANA ENESCU, FLORINA VIOLETA ANGHELINA, ELENA VALENTINA STOIAN, VERONICA DESPA MATHEMATICAL MODELLING OF THE STRESS-STRAIN CURVE FOR 31VMN12 ECOLOGICAL STEEL In this paper, optimum hot formation processing parameters for 31VMn12 steel were established, the torsion deformation of 31VMn12 steel was investigated at temperatures from 900, 1000, 11000C and strain rates from 0.05 s-1 to 3 s. –1. There were studied the structural aspects of materials, in microstructures by electronic microscopy. The stress level decreases with increasing deformation temperature and decreasing strain rate, which can be represented by a Zenner-Hollomon parameter. The mathematical model presented in the paper describes the relationship of tension strain, voltage and temperature coefficient 31VMn12 steel at high temperatures. The stress-strain curves determined by the torsion test allowed the calculation of the Zenner–Hollomon parameter corresponding to the maximum stress. By using this parameter has established a set of equations that reproduce completely stress-strain curve, including the hardening, the restoration and dynamic recrystallization area. Comparisons were made between the experimental results and the predicted and confirmed that constitutive equations developed can be used for mathematical modelling and other attempts (forging, compression) and other types of steel.
Keywords: flow stress, hot compression deformation, the Zener Hollomon parameter, constitutive equation, activation energy