Improvement of the technology for railway wheel steel vacuum processing

Abstract

The analysis of data on the production of wheel steel grades “2” and “T” according to GOST 10791-2011 in the conditions of the of the electric furnace shop of Ural Steel JSC is presented. The content of hydrogen and nitrogen is significantly less than the regulated ones on most heats, which indicates an irrational vacuum mode. Such modes lead to an increase in energy costs for redistribution. All this testifies to the available reserves for improving the vacuum technology. As a result of research, it has been determined that in order to guarantee the production of hydrogen content less than 1.5 ppm and nitrogen up to 0.007 %, it is necessary to carry out vacuum treatment of steel at a residual pressure in a vacuum chamber of up to 3 mbar, the duration of processing in a high vacuum is at least 20 minutes, and argon consumption is blowdown not less than 0.05 m3/t, metal overheating from 110 to 130 °С. The overheating range of the steel before the start of the vacuum treatment the optimal temperature conditions for casting the steel. The optimum temperature of metal overheating at the beginning of processing on steel degassing installation is ~ 115-125 °C with a duration of vacuum treatment of 50-55 minutes (loss of metal temperature 70-75 °C), with overheating of the metal in a steel-pouring ladle before the start of casting 35-45 °C and at loss of metal temperature during transportation to casting 5 °C (15 min). Regression equations are obtained that allow predicting the results of degassing, as well as selecting the values of the vacuum treatment parameters in order to achieve a given content of dissolved gases – hydrogen ([H], ppm) and nitrogen ([N], %).The research was conducted under financial support of the RF Ministry on Science and Higher Education (PROJECT No. FZRU-2020-0011).