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Increased use of powder-forged connecting rods in the automotive industry prompted an investigation into the suitability of powders from different suppliers for this application. Specifications developed by North American users call for ultra clean powders to enhance machinability and fatigue life. Powders from four manufacturers were each blended with graphite and lubricant, then pressed, sintered and forged to full density. Metallographic samples were prepared and evaluated for inclusion content. In addition, the powders were mixed to the composition of connecting rods, (C - 0.5%, Cu - 2% and MnS - 0.3%), and were similarly pressed, sintered and forged. Test bars were machined from the forged discs. Uniaxial fatigue tests were performed in the tension-compression mode and strain-life curves were developed. It was determined that all powders examined were very clean and were comparable in their inclusion content.

The constant challenge for automotive engineers to design vehicles with greater reliability at lower cost has brought powder metallurgy (P/M) to the foreground. This technology provides parts to or near net shape and results in savings of material, energy, capital equipment and floor space. This paper is an extension of SAE reports 850458 and 870133 and describes automotive powder metal components not previously identified. It should help engineers find cost effective applications early in the design stage so that P/M technology can be efficiently adopted. In addition, recent important technological developments in the P/M field applicable to automotive parts are highlighted. In particular, increased reliability achieved through SPC is stressed. A novel blending process is described whereby the alloying ingredients are “glued” to iron powder particles resulting in an increase in P/M quality through improved homogeneity.