hot deformation, stress, approximation, mathematical simulation, aisi304, compression.

The increasing of the efficiency of technological modes of steel products manufacturing requires simulation of metal forming during hot deformation. To obtain correct results, one should set the correct initial and boundary conditions, including the mechanical properties of materials, which represent the dependence of the stress-strain and strain rate at maintained temperature. In the experiments one must reveal the mechanical properties and constants of the steels according to strain rate, predetermined temperature and chemical composition. So, the type of test is usually dependents on the technology process, which simulation will be using the obtained information. One can identify four main types of tests used in the hot deformation: compression, tension, torsion and rupture tests. The simplest tests are considered as uniaxial compression or tension tests. The results of these tests are the curves of «flow stress – strain». The present study describes an approximation method of test results for uniaxial compression of cylindrical samples made from AISI304 steel. During this work a mathematical model of the «stress – strain» relation has been described. An algorithm that determines the necessary numerical coefficients for this model was developed. As a result, the equation of the material state, which is characterized by the stress relation on the strain, strain rate (0.15, 0.5, 1.5, 5 and 15 inverse seconds) and temperature (800, 950, 1080 and 1200 degree Celsius) was found. Also the approximation comparison with the experimental results were obtained.

Puzino, Yury Alekseevich Postgraduated student, department of mechanics and mathematical simulation, National Research University «Higher School of Economics», Moscow