Functional Material Design for High-Density PM Connecting Rods
PM²TEC 2001, in New Orleans, USA. Authors: Paul Skoglund, Sven Bengtsson. A con rod for a modern passenger car engine has been studied to show the performance of high-density PM-materials manufactured by warm compaction of high compressible low alloyed powders. The con rod design was optimized with respect to weight and fatigue performance by finite element analysis. Prototypes manufactured from the diffusion alloyed powder D.HP1 with 0.7%C have been tested and found to meet the design goal of a fatigue safety factor exceeding 1.5 at engine peak power. Results from the endurance tests on these warm-compacted con rods were used as a base for further improvements of mechanical strength and reliability of the manufacturing process. Fractographic investigations have led to both a better understanding of the probability for failure, as well as suggestions to design improvements for reduced scatter of fatigue strength. This paper presents a functional material design for warm compacted connecting rods with a performance similar to the currently used con rods. The design and the procedure for prototype manufacturing are described. Results from fatigue tests on both test samples and connecting rods are given. The results show that warm-compaction of robust low-alloyed powders offers the potential of reduced total cost due to less machining and fewer processing steps.