Vliv technologie dezoxidace na čistotu oceli

Abstract

At the end of 2006, a new agregate ISSM (Integrated system of secondary metallurgy) was build in the steelplant of EVRAZ Vítkovice Steel. The new agregate is a vacuum ladle furnace. In 2009, the steelplant produced more than 95% of its whole production by a technology flow composed of: a convertor OXYVIT – a ladle furnace LF – a ladle furnace ISSM – a continuous casting. This technology flow has brought the best results, concerning the quality of a final product, in the history of the steelplant. In spite of this significant accomplishment, the technology flow needs to be continuously developed so that further improvements can be achieved. A great part of EVRAZ Vítkovice Steel production consists of high quality steel, such as steel for pipeline in acid environement, with good HIC resistance (X70 až X100), which has to meet following criteria: - a content of sulphur in steel must be under 20 ppm - a content of hydrogen in steel must be under 2 ppm - enhancing the inner purity of steel (as few inclusions as possible) Therefore, this study focuses on the technologies of steel cleaning. An analysis of bibliography provided a deeper introduction into following propositions. First, an influence of chemical compositin of slag on desulphurization of steel and faster achievement of thermodynamical equals. Second, possibilities and conditions for succesfull degassing of steel. Third, a creation, modification and removal of inclusions, both at atmospheric pressure and vacuum. In the experimental part of the study, two different deoxidation technologies and their influence on desulphurization, degassing and reduction of inclusions were compared. This research was conducted within the project program TIP FR-TI1/186 a FR-TI1/477, under the financial support of Ministry of Industry and Trade of the Czech Republic.