SMYK Grzegorz AGH University of Science and Technology

Spoluautoři KUZIAK Roman, PIETRZYK Maciej

The model of rolling and controlled cooling process for rails is described in this paper. Coupling microstructure evolution model with the thermal-mechanical FE code was the basis of the model. Thus, the model allowed to calculate metal flow, temperature field and microstructure development during rolling and cooling of rails. Microstructure evolution was simulated using closed form equations describing grain size and recrystallization kinetics. Kinetics of phase transformation was simulated by the Avrami equation. Identification of the flow stress model and the phase transformation model was carried out on the basis of plastometric and dilatometric tests, respectively. As a results microstructure parameters after the cooling and mechanical properties of the final product were calculated. FEM software Larstran was used in simulations of the rolling process. User procedures in Larstran were used for implementation of microstructure development model for rail steel. Structure of the Larstran software and schematic diagram of the user producers are presented in the paper. Temperature distribution and grain size calculated for the last pass of rolling were the input data for further simulation of temperature field and phase transformations kinetics during the cooling process. Simulations of cooling were performed using Authors’ FEM software with implemented model of phase transformations for pearlitic steel. Results for the rolling sequence and for chosen cooling process are presented in the paper. The optimization problem can be formulated basing on these results. It is shown that the selection of the best parameters for the rails manufacturing is possible.

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