Fatigue Strength of Bearing Metals Lining on Steel Plates in Lubricating Oil

Abstract

In the previous paper, plain bending fatigue tests were carried out on tin-base white metal lining on steel plate in lubricating oil and the fatigue strength of the metal was discussed in terms of the crack propagation rate. In the present paper, the fatigue tests are made on lead-base white metal and copper-lead bearing alloy to find the effects of lining thickness, operating temperature and activity of lubricating oil on their fatigue strengths. Lining metals are different in fatigue strength from the bulk metal and the bending fatigue strength of lining metals shows the same tendency as the endurance under bearing tests which is, however, variable with test procedures. The fatigue strength of metals increases as the lining thickness decreases. The larger the ratio of the elastic modulus of backing metal to that of lining metal, the greater is the effect of lining thickness on the fatigue strength. The fatigue strength of lead-base white metal is more affected by temperature than that of tin-base white metal. The fatigue strength of the metal is decreased by the chemical adsorption of lubricants at the tip of fatigue crack. On lead-base white metal and copper-lead alloy, the fatigue strength also decreases due to the surface pre-corrosion by free fatty acid in oil.