A simple, but comprehensive model of heat transfer and solidification of the continuous casting of steel slabs is described, including phenomena in the mold and spray regions. The model includes a one-dimensional (1-D) transient finite-difference calculation of heat conduction within the solidifying steel shell coupled with two-dimensional (2-D) steady-state heat conduction within the mold wall. The model features a detailed treatment of the interfacial gap between the shell and mold, including mass and momentum balances on the solid and liquid interfacial slag layers, and the effect of oscillation marks. The model predicts the shell thickness, temperature distributions in the mold and shell, thickness of the resolidified and liquid powder layers, heat-flux profiles down the wide and narrow faces, mold water temperature rise, ideal taper of the mold walls, and other related phenomena. The important effect of the nonuniform distribution of superheat is incorporated using the results from previous three-dimensional (3-D) turbulent fluid-flow calculations within the liquid pool. The FORTRAN program CONID has a user-friendly interface and executes in less than 1 minute on a personal computer. Calibration of the model with several different experimental measurements on operating slab casters is presented along with several example applications. In particular, the model demonstrates that the increase in heat flux throughout the mold at higher casting speeds is caused by two combined effects: a thinner interfacial gap near the top of the mold and a thinner shell toward the bottom. This modeling tool can be applied to a wide range of practical problems in continuous casters.

http://ccc.illinois.edu/pdf files/publications/03_mtb_meng_con1d_reprint_post.pdf

Heat-transfer and solidification model of continuous slab casting: CON1D

Continuous casting is a mature, sophisticated technological process, used to produce most of the world’s steel, so is worthy of fundamentally-based computational modeling. It involves many interacting phenomena including heat transfer, solidification, multiphase turbulent flow, clogging, electromagnetic effects, complex interfacial behavior, particle entrapment, thermal-mechanical distortion, stress, cracks, segregation, and microstructure formation. Furthermore, these phenomena are transient, three-dimensional, and operate over wide length and time scales. This paper reviews the current state of the art in modeling these phenomena, focusing on practical applications to the formation of defects. It emphasizes model verification and validation of model predictions. The models reviewed range from fast and simple for implementation into online model-based control systems to sophisticated multiphysics simulations that incorporate many coupled phenomena. Both the accomplishments and remaining challenges are discussed.

Review on Modeling and Simulation of Continuous Casting

Mold-slag friction and fracture may cause heat-transfer variations in continuous casting, which leads to steel shell temperature and stress variations, resulting in surface cracks Analytical transient models of liquid slag flow and solid slag stress have been coupled with a finite-difference model of heat transfer in the mold, gap, and steel shell to predict transient shear stress, friction, slip, and fracture of the slag layers The models are validated by comparing with numerical models and plant measurements of mold friction Using reported slag-fracture strength and time-temperature-transformation (TTT) diagrams, the models are applied to study the effect of casting speed and mold-powder viscosity properties on slag-layer behavior between the oscillating mold wall and the solidifying steel shell The study finds that liquid-slag lubrication would produce negligible stresses A lower mold-slag consumption rate leads to high solid friction and results in solid-slag-layer fracture and movement below a critical value Crystalline slag tends to fracture near the meniscus and glassy slag tends to fracture near the mold exit A medium casting speed may be the safest to avoid slag fracture, due to its having the lowest critical lubrication consumption rate The high measured friction force in operating casters could be due to three sources: an intermittent moving solid slag layer, excessive mold taper, or mold misalignment

/pdf/modeling-transient-slag-layer-phenomena-in-the-shell-mold-52sd134hyt.pdf

Modeling transient slag-layer phenomena in the shell/mold gap in continuous casting of steel

Heat transfer—A review of 2005 literature

Effect of substituting CaO with BaO on the viscosity and structure of CaO-BaO-SiO2-MgO-Al2O3 slags

With the drive to cast higher quality, many minimills are adopting mould powder as a lubricant for the continous casting of steel billets. Over the past three decades considerable experience has been accumulated on the relationship between mould behaviour and billet quality for oil lubrication, but comparatively few studies have been conducted for mould powder lubrication. This study, conducted at a Canadian minimill, involved instrumenting four faces of a copper mould with thermocouples and monitoring mould temperatures during casting of 208 × 208 mm billets with mould flux lubrication. Billet samples were also taken to coincide with periods of measurements. Mould temperatures were monitored for two different mould powder compositions, for different mould oscillation frequencies, two mould cooling water velocities, and a range of steel compositions. An inverse heat conduction model was developed to calculate mould heat transfer from the measured temperatures. In this paper, which is the first par...

C.A.M. Pinheiro

Papers

Mould heat transfer and continuously cast billet quality with mould flux lubrication Part 1 Mould heat transfer