Application of the Mixed-Mode Model for Numerical Simulation of Pearlitic Transformation
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JMEPEG (2019) 28:3136–3148 https://doi.org/10.1007/s11665-019-04069-0
Application of the Mixed-Mode Model for Numerical Simulation of Pearlitic Transformation Monika Pernach (Submitted December 29, 2018; in revised form March 26, 2019; published online May 10, 2019) 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. Keywords
diffusion equation, mixed-mode approach, multiscale numerical model, pearlitic phase transformation, physical simulations, rails
1. Introduction Fully pearlitic steels are of great importance in a number of extremely demanding structural applications, in a large part due to their combination of strength and toughness (Ref 1). These exceptional properties are controlled by the microstructures developed in pearlitic steels, especially interlamellar spacing, pearlite colony size and prior austenite grain size. Among many applications of pearlitic steel we can distinguish wires (Ref 2) and rails (Ref 3) investigated in the present paper. The latter application is investigated in the present paper. Prediction of the relation between perlite microstructural parameters and the product in-use properties is crucial for the design of the manufacturing technology. Numerical models of pearlitic transformation can support process of designing of rails manufacturing technology, which leads to costs reduction and improves the quality of finished products. The existing description of pearlitic transformation and pearlite microstructure, based on kinetics of transformation and volume fractions of phases only, is imprecise. A detailed description of the microstructure features of pearlitic steels is required to investigate the correlation between the complex microstructure and the exploitation properties. Indeed, advanced full field models based on the explicit representation of the microstructure ha
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