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


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

  • Source
    [Show abstract] [Hide abstract]
    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.
    Preview · Article · Feb 1965
  • [Show abstract] [Hide abstract]
    ABSTRACT: Unisteel machines were used in investigations of rolling fatigue of a bearing steel and found to provide a useful means of comparing the effects of fire-resistant fluids on the fatigue resistance of the steel. The effects of the properties of the steel specimens were examined and steel quality and hardness were shown to be important. Surface finish of the specimens appeared to have no effect over the range of values observed. Interlaboratory tests indicated that individual machines can differ significantly in the values of fatigue life which they produce, so that comparisons should be made on the same machine or same sets of machines.A statistical method was used to compare sets of results and three parameters, the 10% life, the 50% life and the Weibull slope, were used to characterize each set. It was found that the order of merit of the fluid types tested were mineral oil, phosphate ester, invert emulsion and aqueous glycol. The use of mineral oil as a standard fluid for purposes of comparison introduced problems, though it appears that mineral oil could be used with advantage to check the quality of the steel test specimens.
    No preview · Article · May 1972 · Wear
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A carbide factor was derived based upon a statistical analysis which related rolling-element fatigue life to the total number of residual carbide particles per unit area, median residual carbide size, and percent residual carbide area. An equation was empirically determined which predicts material hardness as a function of temperature. The limiting temperatures of all of the materials studied were dependent on initial room temperature hardness and tempering temperature. An equation was derived combining the effects of material hardness, carbide factor, and bearing temperature to predict rolling-element bearing life.
    Preview · Article · Nov 1972
Show more