To satisfy the requirements of motor-car industry in high-quality automobile-body sheet made from the IF steel, the content of carbon and nitrogen should not exceed 0.004 percent each. Such low concentrations of elements are attained during vacuum treatment of liquid steel by the circulation method with the use of oxygen blowing in degasser [1]. However, even during the ladle degassing, in OAO "Severstal," the carbon content less than 0.002 percent was attained under the pressure less than 100 Pa for 10 min [2]. It was reported [3, 4] that for effective decarburization of steel, hydrogen was fed along with argon in the end of vacuum treatment in circulating vacuum degasser. Hydrogen, which is introduced into the system, is initially dissolved in the melt. After that, as metal is fed into the vacuum degasser chamber, hydrogen is evolved from the melt. The formation of hydrogen bubbles facilitates the process of decarburization and increases the degree of carbon removal.
展开▼
