METHOD FOR HEATING TREATMENT BLADE BY CONTROLLING SURFACES PRESSURE OF OIL

摘要

An oil surface pressure control method for heat treatment of an industrial blade is provided to deformation and cracking of the blade due to a cooling rate difference between an interior part and an exterior part of the blade by controlling pressure of a cooling chamber and prolong life of the blade by uniformly maintaining hardness of an interior part and an exterior part of a heat-treated blade and allowing the blade to obtain an excellent heat-treated structure at the same time. In an oil surface pressure control method for heat treatment of an industrial blade, comprising heating and cooling the blade through a heating preparation step(S10), a heating step(S20), a blade moving step(S30), a cooling preparation step(S40), an oil cooling step(S50), a gas cooling step(S60), a subzero step(S70) and a tempering step(S80) to obtain a required structure, the oil surface pressure control method comprises cooling the blade by controlling pressure of a cooling chamber to 100 to 700 mbar, controlling internal temperature of an oil quenching tank to 80 to 100 deg.C and controlling an agitation speed within the oil quenching tank to 5 to 15 Hz when a blade is made of SNCM439 in the oil cooling step. The oil surface pressure control method comprises cooling the blade by controlling pressure of the cooling chamber to a low pressure range between 100 mbar and 500 mbar when the blade has a size of 100 cm^3 or more and has a complicated shape in the oil cooling step.