Hot working of ingots by increasingthe roll diameter during bar rolling

Abstract: In last ten years, the size range of dimensions program has increased and therefore the hot rolling process needs to be analysed and improved. The bar mill at Ovako Sweden AB in Hofors intends to increase the current roll diameter to improve the rolling capacity and to remove the existing bottleneck within the production flow. Therefore, this project is carried out to study the hot working of ingots within the current rolling setup, aiming to evaluate the subsequent change on ingot central deformation and porosity related to roller dimension. In this project, two plant trials are executed at Ovako Sweden AB and after the trials; analyses on ingot central deformation and central porosity are performed respectively with samples from the two trials. The results suggest that, after the first rolling stage, larger diameter rolls results in less pore defects but gives similar central deformation. Indicated from the results, the ingot is likely to have less central porosity but equal central deformation by increasing the roll diameter. After this project, we get a better perspective of the potential to boost the rolling capacity with a new larger roll and the subsequent quality benefits.