Steel Alloy Hot Roll Simulations and Through-Thickness Variation Using Dislocation Density-Based Modeling
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FUNCTIONAL grading or inhomogeneity of the through-thickness material microstructure is an important factor that determines the mechanical properties of hot-rolled metal products.[1] The thickness of a metal slab can be reduced by any number of subsequent roll passes and interpass times at a specific temperature to reach a final desired slab thickness and throughthickness microstructure. To assess the effect of a specific reduction schedule on the through-thickness microstructure of a hot-rolled plate, a finite element analysis (FEA) can be performed.[2,3] A material model that captures all of the relevant deformation mechanisms and physics is required to do this successfully. There are various options available to model recrystallization during the finite element simulation of a hot rolling or roughing process. These options vary in terms of computational complexity, resolution, and fidelity with which the effect of different reduction schedules could be investigated. One option could be to link multiple model resolutions. Multiscale recrystallization modeling strategies could involve linking a finite element code with Monte
G.J. JANSEN VAN RENSBURG is with CSIR Modelling and Digital Science, Meiring Naude´ Road, 0184 Pretoria, South Africa. Contact e-mail: [email protected] S. KOK and D.N. WILKE are with the Department of Mechanical and Aeronautical Engineering, University of Pretoria, Lynnwood Road, 0083 Pretoria, South Africa. Manuscript submitted October 26, 2016.
METALLURGICAL AND MATERIALS TRANSACTIONS B
Carlo Potts,[4,5] cellular automaton,[6–8] phase field models,[9–12] vertex or front-tracking[13,14] as well as level set methods.[15,16] Linking polycrystal plasticity with recrystallization to a hot roll reduction simulation may give detailed results on the effect of different roll reduction schedules on the resulting through-thickness stock variation. The computational complexity and expense of a detailed multi-resolution approach is however an aspect that should be taken into account. As an alternative, a unified set of continuum equations or mean field approach to microstructure evolution and material response may be considered. Baron et al.[17] developed and used a continuum model to represent the microstructure evolution with dynamic recrystallization of a high-strength martensitic steel. The strong dependence of the dynamic recrystallization kinetics on the initial microstructure was taken into account in their model. Another continuum material model by Lin et al.[2] makes use of a normalized dislocation density variable coupled with evolution equations to describe the average grain size as well as recrystallized volume fraction. Lin et al.[2] used a set of unified viscoplastic equations to model a two-roll pass reduction schedule, which was also later used to model the microstructural evolution during hot cross-wedge rolling.[18] This illustrates the continued usefulness and relevance of continuum-based recrystallization models in the finite element simulation of material processing. Mean field recrystallizati
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