| 摘要 |
PROBLEM TO BE SOLVED: To estimate the end point of refining at a slight C concentration in molten steel with good accuracy. SOLUTION: The amount of C in waste gases is determined from the amounts of CO and CO2 with respect to the amount of Ar in the waste gases, is sampled at intervals below two minutes after approaching a planned end point and are analyzed within two minutes after sampling. The end point is decided by the concentration of the C obtained by adding the concentration of the C decarburized into the waste gases to the analyzed value of the molten steel approximate to the target amount of the C. Known H is added to the Ar described above and the concentrations of He, N and C in the waste gases are measured by an ICP-HAS analysis and the ratio of the amounts of the gaseous CO and CO2 with respect to the amount of the He in the waste gases is determined. This value is used for calculation of the concentration of the C by the decarburization. This concentration of the C in the molten steel is analyzed by a rapid high-frequency heating combustion method. After the sample for C analysis is collected, the sample is held to >=500 deg.C in the state of a high temperature and the concentration of the C is analyzed by the rapid high-frequency heating combustion method.
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