Method for thermal surface treatment in a continuous casting machine and relative device

Method for thermal surface treatment in line in a continuous casting machine associated with furnaces to heat hot-charge blooms, the method being applied to fine-grain structural steels and being suitable to obviate the precipitation of compounds of aluminium, vanadium, niobium and the like and to eliminate or at least to reduce greatly the surface faults due to tension, the method being carried out in a continuous casting line comprising at least a mould (13), a secondary cooling chamber (14), an extraction and straightening assembly (15) and a shearing assembly (17), the method being applied in cooperation with the extraction and straightening assembly (15) and including an intense, concentrated cooling of the surface of a bloom (19) passing through by means of a cooling fluid under pressure, which is water-based and is sprayed by a plurality of sprayer nozzles (18), the cooling being adapted to the dimensions of the bloom (19) and being such as to produce a surface temperature between about 400 DEG C and about 900 DEG C after the natural tempering caused by the hot core of the bloom (19); and a device suitable to carry out the above method and including a plurality of sprayer nozzles (18) arranged about the circumference of the bloom (19) and facing the bloom (19), the sprayer nozzles (18) being fed by means (22) which deliver a water-based cooling fluid under pressure and which are associated at least with means (23) that regulate the pressure.