Effect of Hardness, Surface Finish and Grain Size on Rolling Contact Fatigue Life of M50 Bearing Steel

Journal of Basic Engineering 01/1960; 82(2):11. DOI: 10.1115/1.3662574

ABSTRACT The effect of hardness, surface finish and grain size upon the compressive rolling contact fatigue strength of M-50 bearing steel has been studied. Considerable testing on the RC Rig and statistical treatment methods have been included. A mathematical expression relating these variables to life expectancy is presented and the optimization of these variables is discussed. It is shown that bearing fatigue of M50 increases by increasing hardness, decreasing surface, and increasing grain size. The optimum life identified occurs at Rc 64 hardness, 1.5 RMS surface finish, and a grain size of ASTM 2

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    ABSTRACT: The five-ball fatigue tester was used to study the effect of component hardness combinations on the fatigue life of rolling elements subjected to repeated stresses applied in rolling contact. SAE521OO steel balls from the same heat of material were tempered to a range of Rockwell C hardnesses from 59.7 to 66.4. Groups of balls having average Rockwell C hardnesses of 60.5, 63.2, and 65.2 were used as upper test balls and run with lower test balls of nominal Rockwell C harnesses of 60, 62, 63, 65, and 66. Nominal test conditions included an average race temperature of 150 F, 800,000-psi maximum (Hertz) compressive stress, and a highly purified naphthenic mineral oil lubricant. The fatigue life results were compared with component hardness combinations, plastic deformation of the upper test ball, retained austenite, grain size, and contact temperature. The following results were obtained.
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    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.
    Materials Science and Technology 12/2011; 28(1):58-69. · 0.75 Impact Factor


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