Microstructure and mechanical properties of Fe-C-CU powder-forged connecting rod

Powder-forged (P/F) connecting rods have been widely used due to their advantages of high strength, less machining, light weight, and consistency etc.. Currently, P/F connecting rods were only supplied by GKN in Britain and Metaldyne in US in commercial quantities. In this work, the microstructure and mechanical properties of the P/F Fe-C-Cu automobile engine connecting rods (H16) were designed and manufactured domestically, and the factors affecting the fatigue performance were systematically analyzed. The Measured results indicate that the density of the connecting rod is greater than 7.80 g/cm³. Microstructure observation showed that there were no oxide penetrations or network near or at rod surface and the surface decarburization layer is thinner than 70 mm. Anisotropy at different locations inside the P/F connecting rod was revealed. Furthermore, the bending of connecting rods was found to affect the fatigue performance significantly. The microstructure and the surface shotpeening condition had certain influence on the sites of fatigue crack initiation. Most importantly, the fatigue strength of H16 P/F connecting rod was found to be superior to that of the wrought steel-forged connecting rod (C70), and similar to that of P/F connecting rods designed and manufactured by entities.