Rolling bearing steels – a technical and historical perspective

Abstract

Starting about 1920 it becomes easier to track the growth of bearing materials technology. Until 1955, with few exceptions, comparatively little progress was made in this area. AISI 52100 and some carburising grades (AISI 4320, AISI 9310) were adequate for most applications. The catalyst to quantum advances in high-performance rolling-element bearing steels was the advent of the aircraft gas turbine engine. With improved bearing manufacturing and steel processing together with lubrication technology, the potential improvements in bearing life can as much as 80 times that attainable in the late 1950s or as much as 400 times that attainable in 1940. This paper summarises the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability: the single most important variable that has significantly increased bearing life and reliability is vacuum processing of bearing steel. Differences between through hardened, case carburised and corrosion resistant steels are discussed. The interrelation of alloy elements and carbides and their effect on bearing life are presented. An equation relating bearing life, steel hardness and temperature is given. Life factors for various steels are suggested and discussed. A relation between compressive residual stress and bearing life is presented. The effects of retained austenite and grain size are discussed.

Rework solution method on large size radial roller bearings

“…Bearing half-included outer race angle, in degree C r Basic dynamic radial load rating, in newtons b m Rating factor for contemporary, commonly used, high-quality hardened bearing steel in accordance with good manufacturing practices, the value of which varies with bearing type and design f c Factor, which depends on the geometry of the bearing components, the accuracy to which the various components are made, and the material C r ′ Modified dynamic radial load rating, in newtons S Reliability (probability of survival), in percent N Life, number of stress cycles L Life, number of stress cycles/hours, in millions of revolutions/hours L 10 Basic life with 10 % failure probability (90 % survival), in millions of revolutions a 1 Life modification factor for reliability a 2 Adjustment factor for bearing materials and processing a 3 Adjustment factor for bearing operating conditions including operating profile/mission a 23 Adjustment factor for bearing including interrelationship of material and lubrication effects L z Life of stressed volumes, in number of stress cycles/hours L 1 − z Life of unstressed volumes, in number of stress cycles/hours L or Life of the outer raceway, in hours L ir Life of the inner raceway, in hours L re Life of the rolling element set, in hours…”

Editorial

“…We are fortunate to have been able to persuade Zaretsky, one of the pioneers of the subject, to contribute a historical perspective to this special issue. 1 An area of considerable uncertainty in bearing metallurgy is the relationship between microstructural changes and failure during service. Some of these changes are obvious in etched metallographic samples, for example the white etching regions which are often associated with microscopic cracks or are found in association with failed bearings.…”

The correlation between ZDDP tribofilm morphology and the microstructure of steel

“…100Cr6 is a low alloy through hardened bearing steel. It is also the most popular bearing material [34]. After heat treatment typical for bearing applications (austenitisation at approximately 860 C followed by quenching and tempering at about 160 C) its microstructure consists of a tempered martensite matrix, 6-16 vol.% of retained austenite 1 [35,36] and approximately 3-4 vol.% of residual carbides 2 [26].…”