Narrow composition control method for free-cutting non-quenched and tempered steel comprising sulfur, aluminum and nitrogen

Abstract

The invention discloses a narrow composition control method for free-cutting non-quenched and tempered steel comprising sulfur, aluminum and nitrogen. The method comprises the procedures of converter steel making, LF refining and VD vacuum treatment, wherein the converter steel making procedure comprises the steps that 0.5-2.0 kg/t of steel reinforced aluminum, an alloy material, 5-10 kg/t of nitrided ferromanganese, 5-10 kg/t of lime and 5 kg/t of premelted slag are added in sequence during tapping, and 1-3 m/t of Al wires are fed behind a furnace after tapping is completed. Through the method, narrow composition control over the contents of S, Al and N in the free-cutting non-quenched and tempered steel can be achieved, the difference between the upper limit and the lower limit of the content of S can be controlled to be 0.010%, the difference between the upper limit and the lower limit of the content of Al can be controlled to be 0.010%, and the difference between the upper limit and the lower limit of the content of N can be controlled to be 0.0030%. Through the method, the contents of the compositions of sulfur, aluminum and nitrogen can be effectively controlled, thus, the product quality and stability are improved, the reject ratio in the production process is lowered, and the method has the characteristics of being low in cost, high in efficiency and the like.

Description

technical field [0001] The invention relates to a steelmaking method, in particular to a narrow composition control method for free-cutting non-quenched and tempered steel containing sulfur, aluminum and nitrogen. Background technique [0002] At present, society’s requirements for low-carbon, energy-saving, and green are increasing day by day. Non-quenched and tempered steel can obtain the performance of quenched and tempered steel by adding microalloy elements such as N, V, and Ti and controlling cooling, which can save heat treatment process, The realization of energy saving and consumption reduction in the production process has drawn widespread attention from the iron and steel manufacturing industry. With the in-depth research on non-quenched and tempered steels in metallurgy and related manufacturing industries at home and abroad, it has become an important requirement for non-quenched and tempered steels to meet the needs of easy cutting and good plasticity, toughnes...

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Problems solved by technology

[0005] Chinese Invention Patent Publication No. CN 104372263 A discloses an electric furnace production process for high-purity non-quenched and tempered crankshaft steel. The process is electric furnace smelting-LF refining-VD treatment-continuous casting, wherein the composition of S, Al and N elements is controlled They are all arranged in the process before LF. After the subsequent VD treatment, the content of the three elements is prone to large deviations, and

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