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Application of a bearing steel requires a knowledge of how the steel will change size at the temperatures of bearing operation, to determine if the changes in geometry will effect bearing performance. The concern is greatest for through hardened steels whose entire volume is subject to expansion from transformation of retained austenite and contraction from tempering of martensite. This paper presents size change data for 52100 and 52100 Mod. II steels for aging temperatures from room temperature to 220°C (425°F), and for M50 and stainless bearing steels aged up to 425°C (800°F). Historic papers establishing the fundamentals of stability in low alloy steels are reviewed. Behavior of high alloy and stainless bearing steels is explained.

The effects of surface and near surface tensile stresses on rolling contact fatigue initiation are discussed, based upon measurement of residual stresses and observations of bearings run under both full lubrication (high lambda) and thin film (low lambda) conditions. Previous work considers the applied tensile stresses of interference fit and high speed rotation which effect the macroscopic Hertzian stress field. This paper also takes into account the localized contact stresses and residual stresses at the microscopic sites of stress concentrations. The origins of most rolling contact fatigue failures are at or very near the rolling contact surfaces. Residual stress data for through hardening and case hardening steels are presented. High tensile stresses on the order of 700 MPa (100 ksi) from poor grinding and 480 MPa (70 ksi) from high DN operation cause early failures.

Tensile stresses in bearing components, particularly in rings, may be caused by conditions of manufacturing, mounting, or operation. During bearing operation, when a condition to cause tension is present, the stress cycle varies rapidly between compression when the Hertz contact stress is applied and tension when the contact stress has passed. Analysis of 14 bearing failures indicates that tensile stresses as low as 140 to 200 MPa (20 to 30 ksi) are sufficient to cause cracks to grow in fatigue. When tensile stresses drive the crack in a radial direction, fracture rather than spalling will occur.