EFFECT OF THE SPEED OF FEEDSTOCK ON HEAT TRANSFER COEFFICIENT DURING DESCALING IN HOT ROLLING

conference paper

en

Hydraulic descaling is essential to obtaining a high-quality surface in hot-rolled steel. Descaling removes mill scales (mainly iron oxides) from the surface using high-performance water jets which break the structure of the scales and washes them off the steel strip. The strip is then hot rolled. The speed of the feedstock in a mill directly affects the productivity of the line but can negatively affect the surface quality of the rolled steel, since part of the surface may not be descaled properly if the feedstock moves too quickly. Descaling itself combines both mechanical and thermal effects. The available literature attributes merits to both types of effect, and both are always present in the process. The process of descaling was examined in experiments with a standard descaling nozzle for speeds from 0.1 m/s to 2 m/s. The position-dependent values were computed by an inverse task and the heat transfer coefficient was obtained. The experiment with the slowest speed showed a very intense and relatively long-lasting cooling. A change of cooling regime was observed for speeds up to 0.5 m/s, where the average heat transfer coefficient gradually decreased with the speed. The article summarizes these findings and gives insight into various aspects of the hot rolling process.

Hydraulic descaling is essential to obtaining a high-quality surface in hot-rolled steel. Descaling removes mill scales (mainly iron oxides) from the surface using high-performance water jets which break the structure of the scales and washes them off the steel strip. The strip is then hot rolled. The speed of the feedstock in a mill directly affects the productivity of the line but can negatively affect the surface quality of the rolled steel, since part of the surface may not be descaled properly if the feedstock moves too quickly. Descaling itself combines both mechanical and thermal effects. The available literature attributes merits to both types of effect, and both are always present in the process. The process of descaling was examined in experiments with a standard descaling nozzle for speeds from 0.1 m/s to 2 m/s. The position-dependent values were computed by an inverse task and the heat transfer coefficient was obtained. The experiment with the slowest speed showed a very intense and relatively long-lasting cooling. A change of cooling regime was observed for speeds up to 0.5 m/s, where the average heat transfer coefficient gradually decreased with the speed. The article summarizes these findings and gives insight into various aspects of the hot rolling process.

hot rolling, descaling, heat transfer coefficient, inverse heat conduction task

24.05.2017

Tanger, Ostrava

Ostrava

978-80-87294-73-4

Sborník konference METAL 2017

261–266

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