Evaluation of Press & Sinter Connecting Rods with Warm Compaction Process

Conventional forged and powder forged connecting rods (con-rods) for automotive engines have been a successful application for an appreciable amount of time. In recent years several powder metallurgy (P/M) processes have been proposed to eliminate the need for forging, for example heat treatment after sintering or double compacting - double sintering./1/

A new P/M alloy which achieves a density of nearly 7.2 g/cm³ using a Warm Compaction process has been developed. This alloy has high fatigue strength, and high Young's modulus as compared to conventional P/M alloys and processing (single press - single sintering). The new alloy also has machinability as good as wrought steel as determined by a drilling test.

Con-rods made from this alloy, employing the Warm Compaction processes, were evaluated. Weight was almost the same as compared to conventional forged con-rods intended for three-cylinder engines. The shape of the con-rod using the new alloy was determined by finite element analysis with consideration of material properties. The new con-rod satisfied fatigue strength requirements for this type of engine based on axial loading test.