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The performance and microstructural behavior of several bearing steels tested in radial ball bearings were interpreted in terms of their microstructural alterations, residual stress and resistance to tempering. The bearings were fabricated out of 52100, M-50, and M-50 NiL steels and tested under identical conditions: a radial load of 1111 kg to produce a 3.62 GPa maximum Hertzian contact stress and a speed of 3 000 rpm to produce a calculated lambda ratio of 5.5. The plastically deformed region below the ball track surface of bearings which had run for extended periods was examined metallurgically and measurements were made of the hardness and circumferential residual stress. The 52100 steel bearings exhibited a white-etched microstructure in the softened worked region. The M-50 developed much less plastic flow without work softening, and the M-50 NiL exhibited the least microstructural alteration.

This paper presents a method of measuring the actual load distribution within a rolling element bearing. This method has been used successfully to measure the load distribution in both cylindrical and tapered roller bearings, with accuracies of 15% or less when comparing the applied load with the computed resultant load. An example using a tapered roller bearing is given.

Surface damage created by debris significantly reduces the life of rolling element bearings. The metallurgical structure of a bearing raceway can be modified to optimize strength and damage tolerance. The correct balance between raceway strength and damage tolerance can significantly improve bearing life in contaminated environments. Two test procedures exist for measuring the damage tolerance of steels. Both test procedures produce comparable results, which can be correlated using baseline data. Damage tolerant steel produces a significant life improvement in large tapered roller bearings.