A Low-Cost Material Design of Gray Iron for Heavy-Duty Brake Drums 2009-01-0216

For heavy-duty brake drums and rotors, grade G3500 is commonly used per SAE J431. Numerous studies have shown that grade G3500 alloyed with molybdenum (Mo) and nickel (Ni) is necessary in many heavy-duty applications. Because of the recent rapid rise in raw material costs of Mo and Ni, and the manufacturers’ inability to pass the costs onto the customers, there is a real need to develop new chemistries that will provide a relief to the cost pressure while maintaining the performance of the parts. In this paper, a low cost chemistry is proposed based on a material design concept that is centered on the microstructure design, which in turn is based upon the performance requirements of the parts. The chemical composition and casting processes are subsequently constructed to achieve a set of pre-described microstructure characteristics. Dynometer tests of simulated road conditions and limited road tests have shown that the brake drums made with new low-cost chemistry exhibited equal or better performances than the parts made with the existing higher cost chemistry.