Determination of the concentration of carbon in molten steel during vacuum decarburizing process involves interacting a laser beam with gas drawn off from above molten steel surface

摘要

The carbon (C) concentration in molten steel during vacuum decarburization is determined by drawing off some of the gas located at the molten metal surface, passing a laser beam through the drawn-off gas, measuring or detecting CO and/or CO2 by interaction of the gas with at least one wavelength of the laser, and deducing the concentration, mass or amount of C remaining in the steel. Preferred Features: At least part of the laser beam spectrum is between 630 nm and 2.2 microns. The drawn-off gas flow rate is also determined. Each measurement of CO and/or CO2 is carried out on average over a certain time interval. Vacuum decarburization can be implemented by injection of oxygen or neutral gas. The flow rate of injected oxygen is modified as a function of the mass or the amount of carbon remaining in the steel and of the amount of dissolved oxygen initially present in the steel. Vacuum decarburization also comprises injection of argon. Decarburization is stopped when the concentration or the mass or the amount of carbon remaining in the steel is lower than a predetermined threshold value. An Independent claim is given for: (a) apparatus for measuring the concentration of carbon in a bath of molten steel; and (b) apparatus for vacuum decarburizing a bath of molten steel.