Method for producing ultralow-sulfur steel under high vacuum

Abstract

The invention provides a method for producing an ultralow-sulfur steel under high vacuum, the sulfur content of steel discharged by a converter can be controlled below 0.010%; during the LF furnace refine treatment process, the sulfur content can be controlled at 0.005-0.007%, the slag alkalinity in the later stage can be controlled between 2.0-4.5, thereby a CaO-MgO-Al2O3-CaF slag system is formed, the total slag amount can be controlled at 8.5-10kg / ton steel, the argon flow during the whole process is 150-250N1 / min; and a VD furnace high vacuum treatment is carried out by using argon with a flow of 450-550N1 / min for mixing. Thereby the molten slag equivalent of slag can be enhanced, great flip of a molten steel surface can be avoided, the addition of the molten steel nitrogen absorption and impurities can be minimized, rapid operation during desulphurization process can be promoted, the sulfur content of the finished product can be controlled below 0.005%, and nitrogen content of the finished product can be controlled below 25ppm, and the qualified rate of ultralow-sulfur steel production can be increased.

Description

technical field [0001] The invention belongs to the technical field of steelmaking technology, and specifically relates to a method for producing ultra-low sulfur steel based on a converter-LF furnace (ladle refining furnace)-VD furnace (vacuum refining furnace) process. Background technique [0002] With the progress of society, the demand for high-precision steel is increasing, and the downstream users of steel production enterprises—the manufacturers have higher and higher requirements for the quality and performance of steel. Therefore, generally high-quality pipeline steel The [S] content of steel types such as container plates and bearing steels is required to be controlled at 0.005%, or even below 0.005%, which is the so-called ultra-low sulfur steel. At present, although the method of pretreatment of molten iron can control the sulfur content in steel to less than 0.002%, due to the limitation of the materials used in the converter and the desulfurization capacity, t...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a method that can effectively solve the problem of increased nitrogen content and inclusions caused by the forced desulfurization process of the LF furnace, so that the sulfur content of the finished product can be controlled to less than 0.005% to produce ultra-low sulfur under high vacuum conditions. steel method