Carburizing heat treatment process for rolling mill bearing part

Abstract

A rolling mill bearing part carburizing heat treatment technology is characterized in that the rolling mill bearing part is sequentially divided into a surface layer, a secondary surface layer and a core layer from outside to inside according to the carburizing depth, and the carburizing technology is divided into a heating period, a strengthening period, a reliable period, a life prolonging period and a protection period according to the depth and carbon content requirements of the surface layer, the secondary surface layer and the core layer; wherein the carbon potential in the heating period is set to be 0.6%, the carbon potential in the strengthening period, the carbon potential in the reliable period, the carbon potential in the life prolonging period and the carbon potential in the protection period are all set to be maintained to be 1.0% or above and are sequentially increased stage by stage, and the highest carbon potential is not higher than 1.25%; in the carburizing process, by adjusting the carbon potential of each period, it is ensured that the rolling mill bearing part has enough carburizing depth and corresponding carbon content while it is ensured that no thick and large carbide structure is formed on the surface layer; according to actual use inspection, the rolling mill bearing produced after the carburizing heat treatment process is implemented completely meets the use condition requirements of the high-end plate strip rolling mill bearing, the service life and the reliability of the rolling mill bearing exceed international famous brands, and the quality of domestic rolling mill bearings reaches the international advanced level.

Description

technical field [0001] The invention relates to the technical field of carburizing heat treatment for bearing parts, in particular to a carburizing heat treatment process for rolling mill bearing parts. Background technique [0002] The carburizing depth and carburizing heat treatment process of the existing general bearing parts are designed in accordance with the "Technical Conditions for Carburizing Heat Treatment of Rolling Bearing Parts" (JBT888-2011), and the carburizing layer depth is based on the bearing parts (bearing inner ring, bearing outer It is determined by the effective wall thickness of the ring) or the effective diameter of the (bearing roller), and it needs to meet the requirements of the general working conditions of P / Cr < 30% (where P is the actual equivalent load, and Cr is the design dynamic load rating); With the continuous development of the national economy, the production efficiency of metal rolling has been greatly improved, and the working co...

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Problems solved by technology

[0002] The carburizing depth and carburizing heat treatment process of existing general-purpose bearing parts are designed according to the "Technical Conditions for Carburizing Heat Treatment of Rolling Bearing Parts" (JBT888-2011), and the carburizing layer depth is based on the bearing parts (bearing inner ring, bearing outer ring, etc.) Ring) effective wall thickness or (bearing roller) effective diameter to determine, need to meet the general operating conditions P / Cr<30% requirements (where P is the actual equivalent load, Cr is the design rated dynamic load); With the continuous development of the national economy, the production efficiency of metal rolling has been greatly improved, and the operating conditions of high-end plate and strip rolling mill bearings have reached P / Cr≥40%. The depth of the carburized layer is far from being able to meet the market's requirements for high-reliability and long-life rolling mill bearings, and has become a bottleneck restricting the further development of the domestic rolling mill bearing industry to high-end; Well-known brands, such as SKF in Sweden, FAG in Germany, TMKEN in the United States, NSK in Japan, etc., have a huge import volume, and the price is 4-5 times that of domestic rolling mill bearings of the same type. top priority

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