Patent ID: 6093235
Filing Date: 2000-07-25
Classification: C21C

Abstract:
A process for decarburizing a steel melt containing Mn, Al and Si for producing high-chromium steels, comprising the steps of:injecting oxygen into the melt;continuously measuring a rate of decarburization, including calculating as control quantities:a) a duration of an Al--Si oxidation phase at a start of decarburization,b) a duration of a principal decarburization phase immediately following the Al--Si oxidation phase until a transition point from a decarburization reaction to metal oxidation reached, the Al--Si phase and the principal decarburization phase both having a flow of Ar inert gas, andc) a decarburization rate in the principal decarburization phase; andadjusting an amount of oxygen injected depending on quantities measured and calculated during the measuring step, including increasing a quantity of injected oxygen at an accelerated rate immediately following the Al--Si oxidation phase to an oxygen quantity of the principal decarburization phase until the decarburization rate calculated in c) is reached, maintaining the decarburization rate substantially constant for the duration of the principal decarburization phase by way of the injected quantity of oxygen, and continuously reducing the injected oxygen quantity immediately following the principal decarburization phase so that the decarburization rate decreases continuously in time at a time constant.