One of the main causes of in-service spalling of bearing steels is fatigue crack initiation from non-metallic inclusions. At the present time, while the relationship between endurance and cleanliness of bearing steels is obvious, no quantitative relationship between them has been established. The aim of this paper is to present a new quantitative method which predicts the rolling fatigue life distribution of bearings. This approach is based on a model of fatigue crack initiation in the vicinity of an inclusion in the steel matrix and on a simple fatigue crack propagation relationship. This basic model is used in a statistical approach to describe the scatter of fatigue lives using the distribution of inclusions in the Hertzian zone. The fairly good agreement with fatigue results shows that this approach constitutes a real future tool for predicting the influence of the main material parameters on the fatigue life distribution of bearings.

The proceedings of a November 1996 conference in New Orleans, update previous information and present new materials and processing relating to steel for the anti-friction bearing industry. Among other subjects, they cover steel cleanliness and measuring methods, bearing fatigue life, advanced steel

The most widely used steel grade for rolling bearings is based on a steel composition first used almost a hundred years ago, the so-called lC-1.5Cr steel. This steel is used either in a selective surface induction hardened condition or in a through hardened heat treated condition, both yielding exceptional structural and contact fatigue properties. The Lundberg and Palmgren rolling bearing life prediction model, published in 1947, was the first analytical approach to bearing performance prediction, subsequently becoming a widely accepted basis for rolling bearing life calculations. At that time the fatigue life of rolling bearings was dominated by the classical sub-surface initiated failure mode. This mode results from the accumulation of micro-plastic strain at the depth of maximum Hertzian stress and is accelerated by the stress concentrations occurring at the micro internal defects. In common with all fatigue processes, rolling bearing failure is a statistical process: the failures of bearings with high inclusion content tested at high stress levels belong to the well-known family of "Weibull" distributions. Steady improvements in bearing steel cleanliness due, amongst other things, to the introduction of secondary metallurgy steel making techniques, have resulted in a significantly increased rolling bearing life and load carrying capacity. In recognition of this, in 1985 Ioannides and Harris introduced a new fatigue life model for rolling bearings, comprising a more widely applicable approach to the modelling of bearing life based on the relevant failure mode. Subsequently this has been extended to include effects of hardness and of micro-inclusion distributions in state-of-the-art clean bearing steel.

The design of mechanical structures with predictable and improved durability cannot be achieved without a thorough understanding of the mechanisms of fatigue damage and more specifically the relationships between the microstructure of materials and their fatigue properties. Written by leading researchers in the field, this book, along with the complementary books Fatigue of Materials and Structures: Fundamentals and Application to Damage and Design (both also edited by Claude Bathias and André Pineau), provides an authoritative, comprehensive and unified treatment of the mechanics and micromechanisms of fatigue in metals, polymers and composites. Each chapter is devoted to one of the major classes of materials or to different types of fatigue damage, thereby providing overall coverage of the field. This book deals with multiaxial fatigue, thermomechanical fatigue, fretting-fatigue, influence of defects on fatigue life, cumulative damage and damage tolerance, and will be an important and much used reference for students, practicing engineers and researchers studying fracture and fatigue in numerous areas of materials science and engineering, mechanical, nuclear and aerospace engineering.

Presents the up-to-date information on the state of materials fromelectronic, magnetic, and photonic materials, light metals,materials processing and manufacturing, and structural materialswhich are of invaluable benefit to the global industry.

Presents a calculation method for applying the life rating procedure for ball and roller bearings. This guide includes both surface and subsurface failure modes and the effects on bearing life of material, residual stress, lubrication and contamination in addition to applied loading.