NON-QUENCHED AND TEMPERED STEEL AND MANUFACTURING METHOD THEREFOR

摘要

A non-quenched and tempered steel and a manufacturing method therefor. Modifying a prior scheme for non-quenched and tempered steel manufacturing in which cooling precedes finishing, the method at least has a finishing step followed by a cooling step, in which the cooling scheme differs from the cooling scheme of the prior art, which employs only consistently intense/moderate water cooling or air cooling, in that intense cooling and moderate cooling alternate, where intense cooling ensures that the surface temperature of a steel material is reduced rapidly, moderate cooling allows the core temperature of the steel material to be dissipated gradually to the surface, further intense cooling follows to allow rapid dissipation of heat, and intense cooling and moderate cooling can be alternately repeated multiple times on the basis of an actual need. A water cooling scheme combining intense and moderate cooling allows the core temperature and surface temperature of the steel material to converge in a reduced amount of time, thus ensuring the uniformity of the mechanical properties of the steel material.