NON QUENCHED AND TEMPERED STEEL AND MANUFACTURING PROCESS THEREOF

摘要

A non-quenched and tempered steel and manufacturing process thereof. The process alters the cooling mode before finish rolling in previous production of non-quenched and tempered steel; the process at least has a cooling step after the finish rolling step; the process utilizes alternate intense cooling and moderate cooling. The intense cooling can ensure the surface temperature of the steel to decrease rapidly; and the moderate cooling allows the core temperature of the steel to dissipate gradually to the surface; a further intense cooling is carried out to allow rapid heat dissipation. The intense cooling and the moderate cooling can be carried out alternately several times accordingly. A water cooling mode combining intense cooling and moderate cooling allows the core temperature and the surface temperature of the steel to become the same within a short time, the uniformity of the mechanical properties of the steel.