Modelling of microstructural evolution during accelerated cooling of hot strip on the runout table

Prasad, Anil; Jha, Sudhakar; Mishra, N. S.

doi:10.1002/srin.199501147

Cited by 5 publications

(2 citation statements)

References 16 publications

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“…The Nb mechanical properties. [2,4,[12][13][14] In particular, the precipitation additions play a critical role in delaying recrystallization strengthening model of Shercliff and Ashby [15] had been during finish rolling. [1] Consequently, a pancaked austenite adopted for HSLA steels.…”

Section: Introductionmentioning

confidence: 99%

Precipitation behavior and its effect on strengthening of an HSLA-Nb/Ti steel

Charleux

Poole

Militzer

et al. 2001

Metall Mater Trans A

239

135

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The precipitation behavior of a commercial high-strength low-alloy (HSLA) steel microalloyed with 0.086 wt pct Nb and 0.047 wt pct Ti has been investigated using transmission electron microscopy (TEM) and mechanical testing. The emphasis of this study is to compare an industrially hot-rolled steel and samples from a laboratory hot torsion machine simulation. From TEM observations, the Ti and Nb containing precipitates could be grouped according to their size and shape. The precipitates in order of size were found to be cubic TiN particles with sizes in the range of 1 m, grain boundary precipitates with diameters of approximately 10 nm, and very fine spherical or needleshaped precipitates with sizes on the order of 1 nm. The needlelike precipitates were found on dislocations in ferrite and constituted the dominant population in terms of density. Thus, they appear to be responsible for the precipitation strengthening observed in this steel. Aging tests were carried out at 650 ЊC to evaluate the precipitate strengthening kinetics in detail. The strengthening mechanisms can be described with a nonlinear superposition of dislocation and precipitation hardening. The mechanical properties of torsion-simulated material and as-coiled industrial material are similar; however, there are some microstructural differences that can be attributed to the somewhat different processing routes in the laboratory as compared to hot strip rolling.

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Section: Introductionmentioning

confidence: 99%

Precipitation behavior and its effect on strengthening of an HSLA-Nb/Ti steel

Charleux

Poole

Militzer

et al. 2001

Metall Mater Trans A

239

135

View full text Add to dashboard Cite

show abstract

“…Particularly in the last decade, the emphasis has shifted to modelling the austenite decomposition on the run-out table. 31,[33][34][35][36][37] The complexity of the phase transformations in steels as well as of heat transfer of jet impingement boiling 38,39) may have led to this delayed emphasis in developing microstructure models for run-out table cooling. It is the microstructure resulting from the austenite decomposition and, thus, run-out table processing that primarily determine hot band properties.…”

Section: Hot Strip Mill Model Overviewmentioning

confidence: 99%

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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An Effective Approach for the Simulation of the Cooling Process of Steel Strips on Run‐out Tables

Gadala

2007

steel research international

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The cooling process of steel strips on an industry run-out table (ROT) is simulated using an 1D model. In this model, the water bank information is not handled and the ROT directly consists of the jetlines . The simulation creates an advantage to study independently the spacing of jetlines on the cooling effect. In addition , a novel approach is used for time stepping in this study. First, five numbers of time steps are defined for different cooling zones and each number can be determined according to the accuracy requirement and the strip speed . Thus, the time step size is not constant and the total number of time steps can be reduced . Second, each time step is identified with a flag to indicate its belonging to the different zones. With this approach, tracking is not needed and none of the water cooling zones will be jumped over. The predicted coiling temperatures of 1D model simulations are in good agreement with the field measurements.

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Modelling of microstructural evolution during accelerated cooling of hot strip on the runout table

Cited by 5 publications

References 16 publications

Precipitation behavior and its effect on strengthening of an HSLA-Nb/Ti steel

Precipitation behavior and its effect on strengthening of an HSLA-Nb/Ti steel

Computer Simulation of Microstructure Evolution in Low Carbon Sheet Steels

An Effective Approach for the Simulation of the Cooling Process of Steel Strips on Run‐out Tables

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