CN-122013023-A - Method for producing ultra-high clean bearing steel based on residual calcium content control

Abstract

The invention discloses a method for producing ultra-high clean bearing steel based on residual calcium content control, which comprises, calculating the maximum Al content in molten steel according to the O content and Ca content in the molten steel in LF refining process, adding right amount of aluminum wire to make the Al content in molten steel smaller than or equal to the calculated maximum Al content, wherein the calculation formula is as follows, TAl= (2.5 x T O-77) x ln [ (TCa-0.35T O ])/(-0.7TO+1) ], wherein, TAl, TO and TCa are the maximum Al content, O content and Ca content in the molten steel in refining process in ppm. The method can realize the production of the ultra-clean high-carbon chromium bearing steel with the T (O) of less than or equal to 5ppm, wherein the D-class inclusion in the bearing steel is less than or equal to 0.5 grade, and the Ds-class inclusion is less than or equal to 0.5 grade.

Inventors

• LIU HONGBO
• LIU YING
• ZHANG CAIDONG
• CHE XIAORUI
• XIE RONGYUAN
• ZHANG YUNFEI
• LI SHUANGJIANG

Assignees

• 河北河钢材料技术研究院有限公司
• 河钢集团有限公司
• 河钢股份有限公司

Dates

Publication Date

20260512

Application Date

20260304

Claims (5)

1. 1. A method for producing ultra-high clean bearing steel based on residual calcium content control is characterized in that according to the O content and Ca content in molten steel in an LF refining process, the maximum value of the Al content in the molten steel is calculated through a formula, then a proper amount of aluminum wires are added, so that the Al content in the molten steel is smaller than or equal to the maximum value of the Al content calculated, and the calculation formula is as follows: T[Al]=(2.5*T[O]-77)*ln[(T[Ca]-0.35T[O])/(-0.7T[O]+1)]; wherein: t [ Al ] is the maximum value of Al content in molten steel in the refining process, and the unit is ppm; t [ O ] is the O content in the molten steel in the refining process, and the unit is ppm; ca is Ca content in ppm in molten steel during refining.
2. 2. The method for producing ultra-high clean bearing steel based on residual calcium content control according to claim 1, wherein the O content T [ O ] in the molten steel in the refining process is controlled to be 0< T [ O ] < 15.
3. 3. The method for producing ultra-high clean bearing steel based on residual calcium content control according to claim 1, wherein Ca content TCa in molten steel in refining process is controlled to be 0< TCa < 5.
4. 4. The method for producing ultra-high clean bearing steel based on residual calcium content control according to claim 1, wherein the bearing steel is produced by converter/electric furnace smelting, LF external refining, RH/VD vacuum refining and continuous casting.
5. 5. The method for producing ultra-high clean bearing steel based on residual calcium content control according to claim 1, wherein the bearing steel comprises, by mass, 0.3-1.0% of C, 0.1-0.25% of Si, 0.5-1.0% of Mn, less than or equal to 0.010% of P, less than or equal to 0.02% of S, 0.05-1.0% of Cr, less than or equal to 0.0005% of Ca, and the balance of Fe and unavoidable impurities.

Description

Method for producing ultra-high clean bearing steel based on residual calcium content control Technical Field The invention belongs to the field of metallurgy, and particularly relates to a method for producing ultra-high clean bearing steel based on residual calcium content control. Background With the development of industries such as automobiles, railways, energy sources and the like, the bearing ring and the bearing for the rolling bodies have higher and higher requirements on the performance of long contact fatigue life. T.O. and inclusions in steel are key factors affecting the quality and fatigue life of bearing steel, and especially the control of the size and quantity of Ds-type inclusions is the key place for improving the service life of the bearing. Therefore, with the improvement of the grade of bearing steel, the requirements on T.O and inclusions in the steel are gradually improved, for example, the requirements on T.O less than or equal to 6ppm, ca less than or equal to 10ppm and Ds inclusions in special grade high-quality bearing steel are less than or equal to 1.0 grade. In the national standard GB/T38885-2020 general technical condition for ultra-high clean high carbon chromium bearing steel, the control of Ca content in the steel is definitely specified that the production plant should not add calcium and alloy thereof for deoxidization or control nonmetallic inclusion morphology unless the user agrees, and the grade of T < O > < 5ppm, ca < 5ppm and Ds inclusion < 0.5 in the steel is definitely required. Therefore, control of inclusions in some high-end steels typified by bearing steels is of great importance, and has been a recent research focus. The patent with the publication number of CN114959490B discloses a high-carbon chromium ultra-clean bearing steel and a preparation method thereof, wherein the smelting mode is electric furnace-VD-continuous casting, mo+Mg+Al compound regulation and control are adopted, the continuous casting technology adopts the combination of a nail shooting experiment and simulation to predict the solidification tail end, the central porosity and the central crack occurrence rate of a casting blank are reduced, but the influence of the purity control of the bearing steel and Ds type large-size inclusions under the LF-RH smelting technology is not studied. The patent with publication number CN114058970B provides a method for producing bearing steel by adopting weak deoxidizers such as silicon series and manganese series to replace strong deoxidizers of aluminum series, and adopts LF+RH technology to realize that the bearing steel has no D-type and Ds-type inclusions, and O is less than or equal to 0.0010 percent. However, with the improvement of the grade of bearing steel, the requirements for T.sub.O and inclusions in the steel are gradually improved, and the requirements for T.sub.O less than or equal to 5ppm in the ultra-clean high-carbon chromium bearing steel are difficult to meet. The patent application with publication number of CN118703737A provides a method for producing ultra-pure bearing steel with low cost and high efficiency, wherein the waste magnesium refractory material in the converter smelting process is crushed into magnesium refractory material particles which are used as slag-forming raw materials in the converter smelting, and novel refining slag is added to adsorb inclusions at the end point of converter tapping, so that the total number of the inclusions in the bearing steel is remarkably reduced. However, there is no thorough study on the purity control indexes such as T.[ O ] and D class and DS class inclusion of bearing steel. Disclosure of Invention The invention aims to provide a method for producing ultra-high clean bearing steel based on residual calcium content control, which is used for precisely controlling Al content based on residual Ca content and oxygen O content in molten steel in a refining stage according to the control characteristics of ultra-high clean bearing steel inclusion, so as to realize the production of ultra-high clean high-carbon chromium bearing steel with the concentration of T [ O ] less than or equal to 5ppm, the D coarse in the bearing steel less than or equal to 0.5 level and the Ds inclusion less than or equal to 0.5 level. In order to achieve the above purpose, the technical scheme of the invention is as follows: A method for controlling and producing ultra-high clean bearing steel based on residual calcium content comprises the steps of calculating the maximum value of Al content in molten steel according to the O content and Ca content in molten steel in an LF refining process through a formula, adding a proper amount of aluminum wires to enable the Al content in the molten steel to be smaller than or equal to the maximum value of the Al content calculated, wherein the calculation formula is as follows: T[Al]=(2.5*T[O]-77)*ln[(T[Ca]-0.35T[O])/(-0.7T[O]+1)]; wherein: t [ Al ] is the maximum value