Ingot for bearing, and process for producing bearing steel

Abstract

Disclosed is an ingot for bearings which has a composition containing 0.56-0.70 mass% C, 0.15-0.50 mass%, excluding 0.50 mass%, Si, 0.60-1.50 mass% Mn, 0.50-1.10 mass% Cr, up to 0.025 mass% P, up to 0.025 mass% S, 0.005-0.500 mass% Al, up to 0.0015 mass% O, and 0.0030-0.015 mass% N, with the remainder comprising Fe and incidental impurities, and having a eutectic carbide formation index Ec that satisfies 0<Ec=0.25. Thus, a eutectic carbide is inhibited from generating in segregation parts.

Description

technical field [0001] The present invention relates to a material suitable as a raw material for bearings used in automobiles, wind power, conveying machinery, electrical machinery, precision machinery, or other general industrial machinery, etc., and having excellent rolling contact fatigue life characteristics Ingot steel for (or using) the bearing (ingot steel for (or using) the bearing: ingot steel for (or using) the bearing: ingot steel for (or using) the bearing steel). Moreover, this invention relates to the manufacturing method of the steel for bearings (bearing steel) using the said die-cast material for bearings. Background technique [0002] As such a bearing steel, high carbon chromium steel (high carbon chromium steel: JIS G4805 standard SUJ2) is often used. It is generally considered that excellent rolling fatigue life characteristics are one of the important properties of bearing steel, but the rolling fatigue life is reduced by non-metallic inclusions or eu...

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Problems solved by technology

[0010] However, since the temperature in the steel during wetting is not uniform, there is a problem that when the wetting temperature locally exceeds the solidus temperature, it starts to dissolve again locally to cause a eutectic reaction, thereby generating a larger eutectic reaction. Crystalline carbide

[0014] However, although the above-mentioned carburizing or carburizing and nitriding can improve the rolling fatigue life characteristics, it will lead to an increase in manufacturing cost, or increase the deformation and dimensional changes to reduce the yield, so the problem is that it will lead to an increase in product cost.

[0015] In addition, depending on the application of the bearing steel, it is necessary to increase the cross-section (large section), so the equipment for carburizing or carbonitriding needs to be greatly remodeled, so the economic burden is also a problem.

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