Decontamination endpoint judging method, deconvolution endpoint judging device, steelmaking secondary refining method, and method for producing molten steel

摘要

Decontamination endpoint determination method according to the present inventionMeasurements of carbon and oxygen concentrations in molten steel before starting vacuum decarburizationMeasurement of internal pressure of vacuum vesselModel for vacuum decarburization processAndEstimation step of estimating carbon concentration and oxygen concentration of molten steel and carbon dioxide concentration of exhaust gas in vacuum vessel during vacuum decarburization processThe difference between the estimated value of oxygen concentration and the measured value of molten steel at the timing of oxygen concentration measurement of molten steel during vacuum decarburizationThe parameters included in the model equation are corrected so as to reduce the difference between at least one difference between the estimated value of the carbon dioxide concentration of the exhaust gas and the measured value at the timing at which the carbon dioxide concentration of the exhaust gas is measured during the vacuum decarburization process.The carbon concentration of molten steel was estimated using the model equation with the parameter corrected.A determination step of determining the timing at which the estimated value reaches the target value is the completion point of the vacuum decarburization process and.