Control manner null of iron based oxidation physical quantity in decarbonization oxidation zone of directivity electromagnetic

摘要

PURPOSE: To obtain the desired amount of FeO even when the temperature, the dew point, the plate thickness and the surface condition are fluctuated, by detecting the dew point of the atmospheric gas, the furnace temperature or the plate temperature, and controlling the dew point or the like so that the amount of FeO in the decarburized oxide layer during the decarburized annealing which is estimated by the formula may be the target value. ;CONSTITUTION: When grain-oriented silicon steel which is carried into a furnace between the heating zone 2 and the soaking zone 3 of a decarburizing annealing furnace 1 is heated, soaked and decarburized, the oxide layer containing SiO₂ is formed on the surface of the steel plate, and a part thereof is reduced in the reducing zone 4. The water content of the atmospheric gas in the heating/soaking zone which flows in the reverse direction to the plate passing direction and is discharged out of the furnace is consumed in the decarburizing reaction, and the distribution of the dew point is realized according to the reaction in the furnace. The plate temperature and the dew point of the in-furnace atmospheric gas are respectively detected radiation thermometer 13, and a dew-point instrument 14, and an arithmetic unit 15 estimates the amount of FeO by the specified formula based on these detected values and the plate-passing speed of the steel plate 5, the plate thickness, and the C quantity before the decarburizing annealing. One or more parameters among the dew point of the atmospheric gas, the heating temperature, the reducing temperature and the plate-passing speed are controlled so that the difference between the estimated amount of FeO and the target value may be zero.;COPYRIGHT: (C)1994,JPO&Japio