Application of Super Deformation Joining Method to Endless Hot Rolling

— A Study of Solid-State Joining for In-Line Bar Joining of Endless Hot Rolling V —

Abstract

The endless hot rolling concept was introduced to meet the demand for diverse hot-rolled steel sheet products produced by a process that is cost-effective compared with the conventional batch-type process. Endless rolling involves joining the head and tail ends of two bars after rough rolling. A new solid-state joining technology was proposed to instantaneously obtain a joint with high integrity using relatively simple equipment. In this report, we present the mechanism of super deformation joining (hereinafter referred to as “SDJ”) and discuss results of our evaluation of the characteristics of joints to rolling. Super deformation by shearing creates new uncontaminated joint surfaces, and a large upsetting force at the completion of joining promotes metal bonding. SDJ was applied to the joining machine of POSCO POHANG #2HOT, and the use of endless hot rolling in commercial production was started in Jan. 2007. #2HOT is now producing approximately a hundred thousand tons of coils every month by endless hot rolling owing to the stabilization of operation.