Abstract
Tube steel of strength class K60 is produced in the oxygen converter shop of PJSC «Magnitogorsk Iron and Steel Works». Semi-product is melted in oxygen converters, and steel is obtained as a result of continuous processing of me-tal at the ladle processing section of the continuous casting department. The paper considers the peculiarities of ladle processing of pipe metal at this section. For this purpose the array of production data from 50 melts of steel of strength class K60 is analyzed. The ladle treatment of metal was carried out sequentially at ACP (first part), UHS and ACP (second part). The total duration of ladle treatment was 141 min or 2 h and 21 min on average. For its reduction it is recommended to reduce the first part of processing on ACP to 45 min, the second part - to 20 min, vacuumizing – to 30 min. This will reduce the total treatment duration by 31 min or 22% (relative) on average. The calculated values of sulfur and hydrogen removal rate are quite high – 71.4 and 71.9% on average, respectively, the nitrogen removal rate is much lower – 14.1%. The highest assimilation was obtained for niobium – 62.7%, lower – 42.4 and 30.2% for titanium and calcium, respectively. When analyzing the data, a statistically significant (with a probability of 99.9%) increasing linear dependence of titanium assimilation on the content of aluminum dissolved in the metal was established. According to the revealed dependence for obtaining titanium assimilation not less than 45% it is necessary to have the content of dissolved aluminum in steel not lower than 0,0425%.
Keywords:
pipe steel, ladle-furnace unit, vacuator, ladle, processing, technology