Bearing steel and manufacturing method thereof

Abstract

The embodiment of the invention provides bearing steel and a manufacturing method thereof, and relates to the field of smelting. The manufacturing method of the bearing steel comprises the steps of refining according to alloy compositions of high-carbon chromium bearing steel, continuously casting into a casting blank, rolling and cooling. In the process of continuously casting into the casting blank, the current for solidification final end electromagnetic stirring ranges from 335 to 365A, and the frequency ranges from 4.6 to 5.4Hz; the total reduction amount of solidification final end softreduction is within the range from being larger than 16mm to being equal to 17mm; and the reduction amount distribution adopts a four-section type distribution method, the first-section reduction amount and the end-section reduction amount are 0, the reduction amounts of two middle sections are high in the front and low in the rear, and the maximum reduction amount of each pulling-straightening roller is 6mm at most. According to the manufacturing method, a carbide band shape of the bearing steel can be controlled to be below 2.0 grades, and a carbide net shape at a hot rolling state is stablycontrolled to be below 2.5 grades.

Description

technical field [0001] The application relates to the field of smelting, in particular to a bearing steel and a manufacturing method thereof. Background technique [0002] Bearing steel is mainly used to produce bearing balls and rings. The failure of bearing steel due to smelting quality defects accounts for about 65% of the total failures. The smelting quality defects are mainly non-metallic inclusions and uneven carbides. The cleanliness of bearing steel mainly includes: non-metallic inclusions, oxygen content and impurity element content (mainly Ti), among which oxide inclusions (type B) are the most harmful in bearing steel and have a significant effect on fatigue damage. Influenced by it, it is difficult to stably control B-type inclusions within B-fine ≤ 1.0 and B-coarse ≤ 0.5. [0003] The size and distribution of carbides in bearing steel have a great influence on the contact fatigue life of bearings, and large-grained carbides and dense carbides are extremely harm...

AI Technical Summary

Problems solved by technology

In addition, the hazards of carbide defects are equivalent to inclusions. Carbide defects can be divided into: a, carbide liquid precipitation, b, carbide bands, both of which are caused by steel ingots / billets. Grade 3-4 reduces the fatigue life of steel by about 30%; c. Carbide network is the dendrite segregation produced by bearing crystallization. The carbide network increases by 1 level, and the fatigue life of banded carbon will decrease by 1 / 3

[0004] At present, the control of carbide liquid precipitation is relatively stable, and can basically be completely eliminated, but the control of carbide bands and carbide networks is still difficult

Carbide strips are mainly controlled by continuous casting process and high-temperature heating and diffusion, but it is difficult to stably control them below 2.0 grades; carbide meshes can effectively prevent carbonization mainly by reducing the final rolling temperature and rolling deformation or accelerating the cooling rate after rolling The carbide network is precipitated at the original austenite grain boundary, or the carbide network can be improved by subsequent off-line normalizing, but the carbide network in the hot-rolled state is difficult to be stably controlled below 2.5

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