Representative technologies for hot charging and direct rolling in global steel industry

Abstract

Prompted by the oil crisis and global warming, global steelmakers have begun to focus attention on the huge potential of hot charging and direct rolling processes for saving energy and reducing greenhouse gas emissions. New equipment and technologies have been developed in this field. In details, Japan has upgraded its reheating furnaces, applied induction heating and laser welding to endless hot rolling, developed the pair-cross mill for finish rolling and adjusted process parameters to eliminate surface defects of Nb-containing steel. Korea has also achieved endless rolling via super deformation shear joining and developed its own set of systems for the shape control of hot rolled steel products. Europe and America have designed flameless burners and reversing four-high mill stands together with their flying gage change technology and hydraulics systems for reheating and rolling. China has applied chamfered mould technology to eliminate edge and corner defects of microalloyed steel and the semi-endless rolling process to complete its intergrated production. This paper reviews development status of hot rolling and compares technologies and their effects on energy consumption, product quality, productivity and greenhouse gas emissions at global steel works.