Steel rod rolling process

Abstract

A process for rolling steel rod is provided whereby rolling rod at delivery speeds in excess of 15,000 fpm and cooling same after laying it in spread-out ring form on a conveyor is made feasible with less risk of cobbles and improved rod quality especially in the medium to high carbon content range by entering the rod after rolling into the laying head and thereafter cooling same non-uniformly through a grain size growing phase and a transformation phase with the non-uniformity of cooling rate during the transformation phase being kept in substantially inverse proportion to the differences in effective grain size established in the first phase. In addition a very long cooling conveyor which is necessitated by such delivery speeds (not only for high carbon steels but also low carbon and low alloy steels) is provided without requiring additional horizontal space, by arranging the conveyor in a multiplicity of tiers, spaced vertically, running in opposite directions, and being provided with means for transferring the rings from one tier to the next. Cobbles on the conveyor at high delivery speeds are minimized by coiling with 1/2' spacing, and by reforming means adapted for high speed delivery of rings from the conveyor onto an upwardly sloping mandrel surface, or into a curved chute which stacks the rings on their sides. An intermittent reheat method is employed for processing rod where slow cooling and/or heat treatment at a steady temperature is required.