NITROGEN CONTROL IN ARGON OXYGEN REFINING OF MOLTEN METAL

摘要

A method of refining molten ferrous metals or alloys whereby the nitrogen content of the refined molten metal can be adjusted to any desired value from 10 ppm to 90% of the concentration at which nitrogen at ambient pressure is in equilibrium with the nitrogen dissolved in the melt, said process including a decarburization step whereby a gaseous mixture containing oxygen and a monatomic gas is injected below the surface of the metal bath, characterized by injecting in an initial period of time the decarburization a gaseous mixture consisting essentially of oxygen and nitrogen, where the percentage of nitrogen is maintained such that the partial pressure of nitrogen in the atmosphere in contact with the melt is greater than the partial pressure of nitrogen in equilibrium with the content of desired nitrogen to be obtained from the refined melt, thereby causing e The nitrogen content of the melt at the end of the first period of decarburization is greater than said desired nitrogen content; inject in the following period of decarburization a gaseous mixture consisting essentially of oxygen and a monoatomic gas, or oxygen, a monoatomic gas and nitrogen; and continue injection with a monoatomic gas and/or nitrogen until the nitrogen content of the melt is reduced to the desired value. (Machine-translation by Google Translate, not legally binding)