Method for controlling nitrogen content in process of producing aluminium deoxidation high-carbon steel

Abstract

The invention relates to a method for controlling the nitrogen content in the process of producing aluminium deoxidation high-carbon steel. The outlet steel temperature and the end point carbon content are controlled in the steel outlet process of an electric converter, deoxidizing agents are added in a step-by-step measurement mode in the steel outlet process, the slugging effect is improved, the outlet steel argon blowing pressure is controlled, foaming slag is manufactured in the refining process, the refining electricity conduction time, the outlet sulfur content and the aluminum content are controlled strictly, the vacuum nitrogen removal efficiency is improved, continuous casting protective casting is reinforced, and molten steel is prevented from absorbing massive nitrogen. The method effectively and quantitatively uses the double functions of nitrogen absorption and denitrification of surface-active elements in the molten steel, lays emphasis on nitrogen control in the key links of the whole smelting process, a single nitrogen control operating parameter takes the other links or other process indicators into consideration, and effectively reduces the nitrogen content of aluminium deoxidation high-carbon steel smelted by the electric converter to be below 40*10-6.

Description

technical field [0001] The invention relates to a method for controlling nitrogen content in a smelting process, in particular to a method for controlling nitrogen content in the process of producing aluminum-deoxidized high-carbon steel by an electric converter. Background technique [0002] In most cases, nitrogen is regarded as a harmful element in steel, and even in the case of very small nitrogen content, it has a significant impact on the mechanical properties of steel. The harm of nitrogen is mainly manifested in: free nitrogen in the steel forms a solid solution, causing solid solution strengthening, accompanied by aging, which reduces the toughness and plasticity of the steel; forms brittle inclusions with edges and corners with aluminum, titanium and other elements in the steel, reducing The hot and cold deformation processability of steel; when the residual nitrogen in the steel is high, it will lead to the loose macrostructure of the steel and even the formation ...

AI Technical Summary

Problems solved by technology

[0004] Patent 201110440322.4 uses low-nitrogen carburizer to calcined anthracite instead of pitch coke to increase carburization, and realizes the control of nitrogen content brought by the carburizer, but it is limited to this link and the control of nitrogen content is relatively limited, which cannot meet the requirements of Youte Steel. Nitrogen content requirements; patent 201110403472.8 reduces the nitrogen content in steel through the tapping process of the converter and does not blow argon before entering the argon station. Obviously, not blowing argon when tapping is not conducive to the melting of alloy and slag, and is also not conducive to the temperature of molten steel in the ladle The homogenization of nitrogen increases the difficulty of nitrogen control in the subsequent process, and there may also be cold steel at the bottom of the ladle; and patent 201210487536.1 discloses a tapping method that uses two-step addition of alloy deoxidation and does not use aluminum deoxidation to control steel. The amount of nitrogen added to the molten steel. Similarly, this method tends to only consider the nitrogen content control without considering the alloy recovery rate and deoxidation efficiency; -6 , and adding iron oxide balls to the ladle during vacuum treatment can effectively improve the vacuum denitrification rate, but in fact, this method increases the difficulty of controlling the nitrogen content before vacuum treatment on the one hand, and on the other hand, adding oxide iron balls during vacuum treatment The applicability of iron ball operation is limited and there is a risk of increasing inclusions in molten steel; related literature (control of nitrogen in steel and its impact on quality, Steelmaking, 21 (1); effect of dissolved oxygen on nitrogen absorption in molten steel Research, Iron and Steel, 37(4); Behavior of Nitrogen During AOD Process, ISIJ International, 49(10)) reported the dual effects of surface active elements oxygen and sulfur on nitrogen increase and denitrification of molten steel, but these studies only stayed at At the qualitative level, there is no actual emphasis on the quantitative application of surface active elements and their related elements for nitrogen control

[0005] It is also worth noting that most of the current patents and research are aimed at nitrogen control in converters, but few are aimed at nitrogen control in electric furnaces. As a result, the nitrogen content of the finished product is relatively high, so the control of nitrogen content in the electric converter smelting process has more practical significance