Numerical Simulation of Thermal-Structural and Stress States in the Process of Hardening Railway Rails
Authors: Pokrovsky A.M., Voronov Y.V., Tretyakov D.N. | Published: 09.06.2016 |
Published in issue: #6(675)/2016 | |
Category: Calculation and Design of Machinery | |
Keywords: railroad rails, hardening, nonlinear nonstationary problem of heat conduction, kinetics of structural transformations, finite element method, thermos-elastic-plasticity, residual stresses |
The manufacture of high-strength railroad rails is an extremely important issue. It necessitates the development of such methods for numerical analysis of thermal-structural and stress states of rails in the process of hardening that can be used to rationalize rail manufacturing processes. A mathematical model is created that can describe temperature fields, distribution patterns and thermal stresses in a rail during the entire hardening process. The finite element method is used as the basis for solving the nonlinear nonstationary problem of heat conduction and thermo-elastic-plasticity. Boundary conditions of the third kind are used to describe the heat transfer. Modelling of the transformation of austenite into ferrite-carbide in isothermal conditions is carried out using the Avrami equation. The transition from the isothermal kinetics of austenite decomposition to the non-isothermal conditions is described by the theory of isokinetic reactions applying the additivity rule. The calculation results of the temperatures, structures and stresses in a railway rail at different stages of hardening are presented. It is shown that the head of the R65 rail after hardening has the structure of lamellar ferrite-carbide. When quenched in oil, martensite is present only in the structure of the neck and near the rail foot blade. The software developed by the authors can be used to predict the strength of the rail during operation.
References
[1] GOST P 51685–2013. Rel’sy zheleznodorozhnye [State Standard R 51685-2013. Railway rails]. Moscow, Standartinform publ., 2001. 23 p.
[2] Tsvetkov F.F., Grigor’ev B.A. Teplomassobmen [Heat and Mass Transfer]. Moscow, MPEI publ., 2006. 550 p.
[3] Zienkiewicz O.C., Taylor R.L., Fox D.D. The finite element method for solid and structural mechanics. New York, Elsevier, 2014. 657 p.
[4] Vafin R.K., Pokrovskii A.M., Leshkovtsev V.G. Prochnost’ termoobrabatyvaemykh prokatnykh valkov [The strength of heat treatable mill rolls]. Moscow, Bauman Press, 2004. 264 p.
[5] Popov A.A., Popova L.E. Spravochnik termista: Izotermicheskie i termokineticheskie diagrammy raspada pereokhlazhdennogo austenite [Directory treater: Isothermal and thermokinetic decay diagram of supercooled austenite]. Moscow, Mashgiz publ., 1961. 430 p.
[6] Christian J.W. The Theory of Transformations in Metals and Alloys. Pt. I, II Oxford, Pergamon Press, 2002. 1200 p.
[7] Pokrovskii A.M., Ryzhikov A.V. Matematicheskoe modelirovanie temperaturnogo i fazovo-strukturnogo sostoianii pri naplave bimetallicheskogo prokatnogo valka [Mathematical modeling of temperature and phase-structural states during surfacing bimetallic rolling roll]. Mashinostroenie i inzhenernoe obrazovanie [Mechanical Engineering and Engineering Education]. 2016, no. 1, pp. 42–51.
[8] Demmel’ D. Vychislitel’naia lineinaia algebra: teoriia i prilozheniia [Computational linear algebra: theory and applications]. Moscow, Mir publ., 2001. 429 p.
[9] Guliaev A.P., Guliaev A.A. Metallovedenie [Metallography]. Moscow, ID Al’ians publ., 2011. 644 p.
[10] Pokrovskii A.M. Otsenka resursa prokatnykh valkov s uchetom ostatochnykh napriazhenii ot termicheskoi obrabotki [Evaluation of service life of rolls taking into account residual stresses due to heat treatment]. Proizvodstvo prokata [Rolled Products Manufacturing]. 2005, no. 9, pp. 26–31.