Preparation method of high-strength high-nitrogen rare earth stainless bearing steel

Abstract

The invention discloses a preparation method of high-strength high-nitrogen rare earth stainless bearing steel. The preparation method comprises the processes of primary smelting, refining, vacuum degassing, casting, pressurized electroslag remelting and heat treatment. Nitride is added in the pressurized electroslag remelting process, meanwhile, the nitrogen pressure is controlled, the nitrogen content in steel is increased to 0.3%-0.5%, the nitrogen increasing process is stable, and nitrogen distribution is uniform; rare earth elements are added before nitrogen dissolving to purify molten steel, so that the stability and uniformity of the nitrogen dissolving process are further improved, and the strength of the bearing steel is effectively improved; 80-90% of rare earth elements are usedfor purifying molten steel, the rest of rare earth elements are dissolved in the molten steel for microalloying, and the toughness of the bearing steel is remarkably improved through the two parts ofrare earth elements which are matched in a labor-division mode; and in addition, the mode of combining diffusion deoxidation, vacuum deoxidation and rare earth deep deoxidation is adopted, the deoxidation effect is guaranteed, meanwhile, use of aluminum is reduced, harm of the aluminum is reduced, and the anti-fatigue performance of the steel is improved.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a preparation method of high-strength and high-nitrogen rare earth stainless bearing steel. Background technique [0002] High-nitrogen martensitic stainless steel refers to martensitic stainless steel with a nitrogen content greater than 0.08% in steel. The addition of nitrogen in martensitic stainless steel expands the temperature range of the austenite phase region, effectively inhibiting the formation of δ-ferrite; while ensuring interstitial solid solution strengthening, the carbides can be refined, accompanied by nitrogen The dispersion and precipitation of compounds, etc., not only significantly improves the strength and hardness of martensitic stainless steel, but also can maintain the original toughness and improve corrosion resistance. Due to its excellent comprehensive performance, high-nitrogen martensitic stainless steel can be used in fields such ...

AI Technical Summary

Problems solved by technology

At present, the commonly used methods for preparing high-nitrogen steel include pressure vacuum induction melting and pressure electroslag remelting. There is no slag in the process of pressurized vacuum induction, and harmful elements such as oxygen and sulfur in molten steel cannot be removed; pressurized electroslag remelting can remove some harmful elements such as oxygen and sulfur, which can improve element segregation and reduce defects such as pores, but The process of nitrogen addition is unstable, and sometimes requires secondary remelting

[0004] Due to the lack of pressurized metallurgical equipment, domestic research on high-nitrogen steel has lagged far behind many countries in the world. Although some high-nitrogen steel has been produced, it is not as good as foreign countries in terms of trace impurity element content, surface quality and internal quality stability. There is still a big gap for high nitrogen steel, and there are few details on how to achieve high nitrogen dissolution

For example, CN106636895A, CN104018083B, and CN106222545 all disclose components and preparation methods of high-nitrogen martensitic stainless bearing steel, and only briefly mention the electroslag remelting step, but for the specific process of nitrogen dissolving in martensitic steel, Parameters and effects are not explained

In the process of pressurized electroslag remelting, improper smelting process and nitrogen pressure will reduce the effect of nitrogen increase, and even produce defects such as slag grooves, nodules, heavy skin, wrinkles, and slag inclusions, thereby increasing the weight of pressurized electroslag. It is difficult to control nitrogen content and ingot quality in the smelting process, and there are inevitably impurities (such as O, S, Al, etc.) in molten steel, which will also have a negative impact on the dissolution of nitrogen

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