Application of the Mixed-Mode Model for Numerical Simulation of Pearlitic Transformation

Abstract

The multiscale model of pearlitic transformation, including the finite element solution of the second FickÕs equation with moving boundary in the microscale and Fourier equation in the macroscale, is presented in this paper. According to the mixed-mode approach, both the volume diffusion and the interface mobility were considered. Model describes sidewise and frontal growth of cementite and ferrite plates in a single grain of the austenite. Assessment of the possibility of the developed model application to determine the key parameters in terms of strength properties of pearlitic steel, i.e., pearlite grain size and colony size as well as interlamellar spacing for various cooling conditions, was the main aim of this work. The model was validated and verified on the basis of experimental tests performed for two eutectoid steels. In practice, developed model can support design process for a technology of high-strength rods and long products manufacturing. Rails were selected as a case study in this work, and therefore, numerical simulations of accelerated cooling of the rail head were performed and the relationship between the parameters of heat treatment, parameters of the structure and properties of the finished product was determined on the basis of obtained results.

Experimental model of the pearlite interlamellar spacing in lamellar graphite iron

“…Since the interfacial energy and the enthalpy change are relatively independent of the temperature the theoretical relations predict that λ pearlite and undercooling are inversely related [7]. Several empirical models have been developed for the prediction of λ pearlite in the pearlitic steels [8][9][10][11]. These models combine the effect of the alloying temperatures were recorded at approximately 0.2 second interval.…”