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The five basic functions

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Presentation on theme: "The five basic functions"— Presentation transcript:

1 The five basic functions
This section covers: The five basic functions of mold flux. Prepared by the Technical Service Department of Stollberg Inc.

2 Functions of Continuous Casting Mold Fluxes
Prepared by the Technical Service Department of Stollberg Inc.

3 The Three Layers of Mold Flux
Once applied to the mold, the solid mold flux melts due to the heat of molten steel. This is the yellow slag directly above the steel. Between the solid mold flux and the liquid slag is a transition area know as the glass carbon matrix. Solid mold flux Glass carbon matrix Liquid slag Molten steel Prepared by the Technical Service Department of Stollberg Inc.

4 Continuous Casting Mold Flux Performs Five Basic Functions :
Thermally insulates the molten steel meniscus to prevent premature solidification. Protects the molten steel in the mold from reacting with atmospheric gases. Absorbs products of de/reoxidation from the molten steel. Provides a lubricating film of molten slag to prevent the steel from adhering to the mold wall and to facilitate strand withdrawal. Modifies thermal heat removal in the mold. Prepared by the Technical Service Department of Stollberg Inc.

5 The design of the mold flux affects thermal insulation at the meniscus
The thermal insulating property can be controlled through the mold flux’s bulk density, particle size, and carbon type(s). Thermal Insulating Barrier Liquid Slag Molten Steel Prepared by the Technical Service Department of Stollberg Inc.

6 Prepared by the Technical Service Department of Stollberg Inc.
Thermal Insulating Barrier Radiant Heat Radiant heat is absorbed and reflected/deflected by the unmelted mold flux layer to minimize heat loss to the environment. Liquid Slag Molten Steel Prepared by the Technical Service Department of Stollberg Inc.

7 Prepared by the Technical Service Department of Stollberg Inc.
Thermal Insulating Barrier Proper thermal insulation of molten steel meniscus is required to lower shell growth along meniscus radius to allow products of de/reoxidation and/or gas bubbles to enter into the liquid slag pool and not become entrapped by solidifying meniscus hook. Liquid Slag Heat De/reoxidation Products Gas Bubbles Molten Steel Prepared by the Technical Service Department of Stollberg Inc.

8 Prepared by the Technical Service Department of Stollberg Inc.
Your addition rate of mold flux affects thermal insulation at the meniscus The amount of unmelted flux applied by the operator has a direct effect on the fluxes ability to insulate. Unmelted granular powder should be two inches thick, and added in frequent small amounts. Thermal Insulating Barrier Liquid Slag Molten Steel Prepared by the Technical Service Department of Stollberg Inc.

9 Protecting the Molten Steel from Reaction with Atmospheric Gases
The tri-layer mold flux system (dry powder, glass-carbon matrix, and liquid slag) acts as a protective barrier. This protective barrier prevents the reaction of atmospheric gases with constituents of the liquid steel. O H N Dry Powder Glass Carbon Matrix Liquid Slag Al Fe Ti Mn Ti Prepared by the Technical Service Department of Stollberg Inc.

10 Absorb Products of De/reoxidation
Mold fluxes are engineered materials that are designed to react with products of deoxidation and reoxidation. The incorporation of these products of de/reoxidation into the liquid slag improves the quality of the cast section while facilitating its production. Liquid Slag Al2O3 Mn TiO2 TiN Fe3+ Al3+ Ti4+ Prepared by the Technical Service Department of Stollberg Inc.

11 Thermal Heat Transfer in the Mold
Solid Flux Film The slag between the steel shell significantly affects heat transfer. The mold wall is very cold, and causes the slag to freeze into a solid. The solid greatly reduces heat transfer. The slag along the shell stays hot, and in liquid form. It lubricates. Heat Flux MOLD WALL Liquid Slag Solidifying Shell Air Gap Prepared by the Technical Service Department of Stollberg Inc.

12 Provides Liquid Lubrication in Gap Between Mold and Solidifying Shell
Liquid slag is drawn down into the gap along the steel shell. The liquid is a lubricant, allowing the steel to be withdrawn without sticking to the mold wall. If the steel sticks to the wall, it causes a breakout. Solid Flux Liquid Slag Steel Shell Flux Velocity Mold Wall Prepared by the Technical Service Department of Stollberg Inc.


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