Differential quench method and apparatus

The present invention comprises methods of quenching a continuously cast steel product upstream of a reheat furnace that brings the steel to a uniform initial rolling temperature. One purpose served by the invention is to eliminate or reduce the incidence and severity of surface defects in the steel that occur during reduction rolling. There are a number of inventive aspects of the applicant's methods that collectively may comprise more than one invention, but for convenience, reference will be made to "the invention" on the understanding that the term covers the collectivity of inventions claimed herein. Surface defects in rolled steel are remedied by quenching a surface layer of the steel product downstream of the caster and upstream of the reheat furnace by transversely differentiated quenching to match the transverse temperature profile of the steel product. The flow rate of the quench spray is differentially adjustable across the width and optionally the length of the steel product. An array of spray nozzles controlled in transversely or longitudinally arranged groups provides the quench spray.