ABSTRACT
Applications of Lead 535
50 woo
High fatigue resistance is also preferred because of fluctuating stress conditions. Fatigue fractures begin at the bearing surface and penetrate the bearing material until close to the bond between the lining and the steel backing, then proceed parallel to this surface, so that a thin layer of bearing metal continues to adhere to the steel. The lining becomes more and more brittle and, finally, shatters. The low melting point of lead gives rise to a reduction of the fatigue strength with rising temperature. A similar behavior is also to be expected of the white metals based on lead and tin. The life of white-metal linings under dynamic stress is increased by a reduction of wall thickness. A fatigue strength of -15.0 MPa is observed for a steel-backed, tin-based white-metal bearing of 0.2 mm thickness, whereas the fatigue strength was increased to 27.8 MPa for a white-metal layer thickness of 0.04 mm [2]. In addition to fatigue strength, the impact strength of bearing materials is of importance.
