Modeling of the continuous casting of steel—past, present, and future

Abstract

This lecture honoring Keith Brimacombe looks over the history, current abilities, and future potential of mathematical models to improve understanding and to help solve practical problems in the continuous casting of steel. Early finite-difference models of solidification, which were pioneered by Keith Brimacombe and his students, form the basis for the online dynamic models used to control spray water flow in a modern slab caster. Computational thermal-stress models, also pioneered by Brimacombe, have led to improved understanding of mold distortion, crack formation, and other phenomena. This has enabled process improvements, such as optimized mold geometry and spray cooling design. Today, sophisticated models such as transient and multiphase fluid flow rival water modeling in providing insights into flow-related defects. Heat flow and stress models have also advanced to yield new insights. As computer power increases and improvements via empirical plant trials become more costly, models will likely play an increasing role in future developments of complex mature processes, such as continuous casting. FORWARDIt is a great privilege to present the second ever J. Keith Brimacombe lecture at this first Electric Furnace Conference of the Third Millennium, (at least according to the Gregorian calendar). Professor Brimacombe was a giant in many fields. He also inspired many people, especially his students, including me. At the first Brimacombe lecture, last year, Indira Samarasekera [1] , gave an inspirational talk, that touched on many different facets of the research excellence that was the hallmark of this remarkable man's career. Dr. Brimacombe left a legacy of leadership, knowledge and genuine care for the people, which benefited the steel industry, the Iron and Steel Society, and many individuals here today. His technical contributions spanned a B.G. Thomas, Brimacombe Lecture,59 th Electric Furnace Conf., Pheonix, AZ, 2001, Iron & Steel Soc., pp. 3-30 4 wide range of materials engineering processes, including rotary kilns, injection, bath smelting, flash smelting, static and continuous casting, rolling, and microstructural engineering.This year's lecture will look at the history, current state, and future prospects of the mathematical modeling of the continuous casting of steel. Of the many contributions that Dr. Brimacombe gave to process metallurgy, some of his best pioneering work was done to help create this field. He was a champion of modeling and he did much to improve its credibility and usefulness, through his example. This subject is also fitting because his impact on the steel industry through short courses and publications on continuous casting made extensive use of the landmark results of his models. Indeed, he would have been the best choice to lecture on this topic, had he not suddenly left us in 1997. I am grateful to the organizers for asking me to give this lecture in an effort to continue his spirit.

The use of water cooling during the continuous casting of steel and aluminum alloys

“…[32] The mold walls are routinely tapered to match the steel shrinkage in order to minimize air gap formation and to facilitate primary cooling. [34] It is estimated that primary cooling during continuous casting of steel in the mold removes about 40 pct of the total superheat and about 30 pct of the total sensible heat. [11] The surface heat-transfer coefficient typically decreases down the length of the mold from a peak value of 1500 to 2000 W m Ϫ2 K Ϫ1 at the meniscus to about 600 to 800 W m Ϫ2 K Ϫ1 [22] near the mold bottom.…”

Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

“…For the four mentioned models, Kozlowski et al [38] suggested various constitutive relations for p   as functions of stress, temperature, carbon content, activation energy, and various adjustable parameters such as temperature dependent stress exponent, etc. (see also Thomas [99,100] for a review of this subject). In the continuous casting of steel, when mold powder is added to the free surface of the liquid steel, it begins to melt and flow.…”

Intelligent System for Continuous Steel Casting Based on Water Flow Control in the Secondary Cooling Stage

“…The secondary cooling zone has the role to continue the wire cooling after it has emerged from the crystallizing and to assure the total solidification of the semi-product. It is considered "the heart" of a continuous casting and has the role of ensuring the quality of the material, the material surface shape and has to ensure a homogeneous cooling and a uniform repartition of the water on the materials surface [4].…”