HEAT LOSSES OF BLOOM IN THE HOT ROLLING PROCESS

článek ve sborníku ve WoS nebo Scopus

en

The temperature of the bloom during hot rolling is a crucial factor for the quality of the final product. Heat losses during hot rolling which affect bloom temperatures were therefore experimentally investigated. Experiments were designed to simulate heat transfer on the bloom surface during rolling when: 1. the bloom does not move and is far from the work roll (heat transfer by radiation and free convection in air); 2. the bloom moves far from the work roll (heat transfer by radiation and forced convection in air); 3. the bloom moves close to the work roll so the residual water from roll cooling falls on its surface (heat transfer by radiation and forced convection by residual spray from work roll cooling). Roll bite is excluded in this paper. Experiments were performed with an austenitic steel plate embedded with thermocouples. The plate was firstly heated up to 900 °C and then repeatedly moved by a computer controlled mechanism through a section which simulated the blooming line. Three different velocities of 1, 3, and 5 m·s-1 were tested to observe the influence of velocity on the heat losses. The temperatures gathered during the experiments are evaluated numerically by an inverse heat conduction task and analytically. The final results show that the highest heat loss is caused by radiation; its value is 171 W·m-2·K-1for 1,100 °C. The heat loss due to residual water from work roll cooling is 80-88 W·m-2·K-1 and the heat loss by forced air is found to be from13-29 W·m-2·K-1 .

The temperature of the bloom during hot rolling is a crucial factor for the quality of the final product. Heat losses during hot rolling which affect bloom temperatures were therefore experimentally investigated. Experiments were designed to simulate heat transfer on the bloom surface during rolling when: 1. the bloom does not move and is far from the work roll (heat transfer by radiation and free convection in air); 2. the bloom moves far from the work roll (heat transfer by radiation and forced convection in air); 3. the bloom moves close to the work roll so the residual water from roll cooling falls on its surface (heat transfer by radiation and forced convection by residual spray from work roll cooling). Roll bite is excluded in this paper. Experiments were performed with an austenitic steel plate embedded with thermocouples. The plate was firstly heated up to 900 °C and then repeatedly moved by a computer controlled mechanism through a section which simulated the blooming line. Three different velocities of 1, 3, and 5 m·s-1 were tested to observe the influence of velocity on the heat losses. The temperatures gathered during the experiments are evaluated numerically by an inverse heat conduction task and analytically. The final results show that the highest heat loss is caused by radiation; its value is 171 W·m-2·K-1for 1,100 °C. The heat loss due to residual water from work roll cooling is 80-88 W·m-2·K-1 and the heat loss by forced air is found to be from13-29 W·m-2·K-1 .

Hot rolling; heat loss; heat transfer coefficient

30.06.2022

978-80-88365-06-8

Sborník z konference Metal 2022

182–186

5