Lead-Free Replacements for SAE 792 in Bushing Applications

Lead is well recognized as having environmental and health risks. The elimination of lead from automotive components has been accelerated by the European End of Life Directive as well as litigation concerns in the U.S. In response to these circumstances, two new lead-free bronze materials have been developed as replacements for SAE 792 (CuSn10Pb10). The two lead free materials are sintered bronzes with nominal compositions CuSn10Bi3 and CuSn8Ni. The characteristics and performance of these materials are compared and contrasted to sintered and cast SAE 792. Fatigue strength, mechanical properties, corrosion resistance, and wear resistance are described and related to the microstructural and application conditions. The CuSn10Bi3 material is preferred for SAE 792 applications having poor lubrication or high-speed conditions, typically in spark ignition connecting rod bushings or highly loaded transmission bushings. The CuSn8Ni material is directed at SAE 792 applications with higher loads and better lubrication, typically connecting rod bushings in Diesel engine applications.