New Material with Improved Machinability and Strength for Powder Forged Connecting Rods

The powder forging (PF) process is used to produce fully dense powder metallurgy (PM) parts for high performance automotive applications. PF connecting rods have been widely accepted in the US, Japan, and other countries due to higher performance and lower manufacturing costs when compared to conventionally forged steel connecting rods [1, 2]. In order to meet and exceed requirements for higher fatigue strength and better machinability of PF connecting rods, a newly developed machinability enhancer, consisting of complex calcium oxide, named KSX, was introduced [3]. Minimal additions of KSX were found to be very effective in protecting the surface of the cutting tool during machining, with virtually no effect on mechanical properties obtained after the forging process. A comparison study between materials prepared with 0.3% MnS and with 0.1% KSX additions showed higher fatigue strength and better machinability in the case of the mix with KSX. These results were confirmed from fatigue tests on PF connecting rods.