Fatigue crack initiation and early growth in a multiphase Al alloy included in a multilayer material system

The fatigue properties of a multilayer material system employed in the manufacture of small automotive plain bearings are assessed. This comprised three layers; a multiphase Al - Sn - Si lining, a bonding Al interlayer, and a steel backing. The structure was found to exhibit complex fatigue behaviour; including multiple crack initiations, highly microstructural crack growth, and complex crack interaction, coalescence, and deflection events. Key microstructural features are identified for both initiation and early propagation of fatigue cracks within the lining material. The effects of both the layered structure and service environment on fatigue crack propagation behaviour are assessed. This provides valuable information for the development of new lining alloys for future automotive bearing designs.