MetModel: microstructural evolution model for hot rolling and prediction of final product properties

Trowsdale, A.J.; Randerson, K.; Morris, P. F.; Husain, Z.; Crowther, D. N.

doi:10.1179/030192301677911

Cited by 11 publications

(10 citation statements)

References 9 publications

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“…Starting with the pioneering work of Sellars et al [18,19] to predict microstructure evolution during multipass hot rolling, mathematical modeling of hot strip rolling has meanwhile attained a rather advanced state with a number of models being available. [20][21][22][23][24][25][26][27][28][29][30][31][32] At present, these knowledge-based process models, which use the concept of microstructure engineering, are primarily available for conventional plain carbon and HSLA steels. Model development for AHSS is still in its infancy; a first generation of these models is currently implemented for DP steels, [33][34][35][36] but very little work has been reported for TRIP steels.…”

Section: Introductionmentioning

confidence: 99%

A Microstructure Evolution Model for Hot Rolling of a Mo-TRIP Steel

Fazeli

Militzer

et al. 2007

Metall Mater Trans A

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A comprehensive study of microstructure evolution for a Mo-TRIP (transformation-inducedplasticity) steel under hot strip rolling conditions has been conducted. This investigation includes austenite grain growth during reheating, deformation behavior, and static recrystallization kinetics of austenite as well as the effect of cooling rate and austenite conditioning on the continuous cooling transformation (CCT) behavior. The physically based Kocks-Mecking model has been employed to describe the deformation behavior of austenite, while the JohnsonMehl-Avrami-Kolmogorov (JMAK) approach has been used to predict static recrystallization, and an empirical equation has been formulated for the recrystallized austenite grain size. Ferrite transformation start is described by a model considering early growth of corner nucleated ferrite. The fraction of ferrite transformed from austenite during continuous cooling is predicted by the semiempirical JMAK approach in combination with Scheil's equation of additivity. The effect of carbon enrichment on ferrite transformation kinetics is explicitly included in the model. In addition, a phenomenological model for the bainite formation has been proposed. Martensite transformation start is described by an empirical equation taking into account carbon enrichment of remaining austenite. Finally, the entire hot strip rolling and controlled cooling process have been simulated by hot torsion tests, and the optimum coiling temperatures for the formation of TRIP microstructures have been determined.

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Section: Introductionmentioning

confidence: 99%

A Microstructure Evolution Model for Hot Rolling of a Mo-TRIP Steel

Fazeli

Militzer

et al. 2007

Metall Mater Trans A

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“…Starting from the concepts proposed by Sellars et al 2,3) to predict the microstructure evolution during multipass hot rolling and using the similarities with plate rolling, 27) several groups [9][10][11][12][13][14][15][16][17][18][28][29][30][31][32] have developed microstructure evolution models for hot strip rolling. Some of these models are available as commercial software packages whereas others are used in-house.…”

Section: Hot Strip Mill Model Overviewmentioning

confidence: 99%

“…97) As a result, the fraction transformed during continuous cooling can be obtained from 90) ...... (14) where jϭdT/dt is the instantaneous cooling rate and T s the transformation start temperature. While the additivity principle is in general reasonably well fulfilled for the formation of ferrite and pearlite, it is usually of very limited use for the bainite reaction.…”

Section: Austenite Decompositionmentioning

confidence: 99%

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Computer Simulation of Microstructure Evolution in Low Carbon Sheet Steels

Militzer

2007

ISIJ Int.

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Models of microstructure evolution in steels are reviewed. The emphasis of the review is on low carbon sheet steels both hot-rolled and cold-rolled and annealed. First the state-of-the-art on industrial microstructure process models is presented. The individual model concepts for grain growth, recrystallization, precipitation and phase transformations are briefly discussed. The development from empirically-based models to physically-based models is identified as a key issue to have increased predictive capabilities for these models over a wider range of steel grades and operational conditions. The challenges in the development of the next generation of models are delineated. In particular, new aspects of microstructure evolution associated with novel processing routes and advanced high strength steels are evaluated. Further, the majority of the currently employed models are on the macro-scale but future microstructure models will increasingly be meso-scale models that predict actual microstructures rather than a number of average parameters (e.g. grain size, fraction transformed) to describe microstructure evolution.KEY WORDS: mathematical model; microstructure; steel; hot rolling; annealing; grain growth; recrystallization; precipitation; phase transformation. © 2007 ISIJ Reviewvates the development of advanced microstructure models that provide an increased insight into the underlying physical metallurgy principles. Further, AHSS are frequently produced as cold-rolled annealed and/or coated sheets. Here, the intercritical annealing step assumes a crucial role to obtain the desired complex, multi-phase microstructures. Intercritical annealing constitutes a paradigm shift from annealing of conventional steels where no cycling through the transformation region occurs. The added complexity of the annealing routes for AHSS requires the development of novel annealing models that also address austenite formation which has received comparatively little attention in process models.Currently available microstructure models for the production of sheet and other steels are usually formulated on the macro-scale, i.e. the microstructure is described with a number of so-called internal state variables such as grain size, fraction recrystallized and fraction transformed. However, the advances in computer technology make it now feasible to routinely conduct modelling of the microstructure on the meso-scale if not on the atomistic level. In particular the meso-scale approach appears to open a new era of modelling the microstructure evolution in sheet steels. In this methodology actual microstructures can be predicted rather than mean values which have traditionally been used to characterize microstructures. The significance of these new modelling strategies is also fueled by the realization that material properties may markedly depend on morphology and spatial distributions of microstructure constituents. [22][23][24] In this paper, first the models proposed for hot strip rolling are reviewed. Special attention is given to the ...

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“…Starting with the pioneering work of Sellars et al 18,19) to predict microstructure evolution during multipass hot rolling, mathematical modeling of hot strip rolling has meanwhile attained a rather mature level; a number of such models are available for conventional plain carbon and high-strength low alloy (HSLA) steels. [20][21][22][23][24][25][26][27][28][29][30][31][32] Model development for AHSS steels is still in its infancy; some initial model concepts have recently been proposed for DP steels [33][34][35][36] and first generation models have also been proposed for TRIP steels. 37,38) The development of microstructure process models for advanced high strength steels is particularly significant since these steels are more sensitive to process conditions than conventional steels.…”

Section: Introductionmentioning

confidence: 99%