NON-QUENCHED AND TEMPERED STEEL AND MANUFACTURING METHOD THEREFOR

摘要

A non quenched and tempered steel and manufacturing process thereof. The manufacturing process of the non quenched and tempered steel has a cooling step after the finish rolling step, wherein intense cooling and moderate cooling are carried out alternatively. 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 according to practical requirement. 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, and thus ensures the uniformity of the mechanical properties of the steel and improves production efficiency.