Impact of Decarburization on the Fatigue Life of Powder Metal Forged Connecting Rods 2001-01-0403
A main requirement for a satisfactory function and service life of a forged powder metal connecting rod is the fatigue strength. Fatigue strength mainly depends on design, material, microstructure, and surface condition. Much work has been accomplished to optimize these factors, but still a variety of surface defects such as localized porosity, roughness, oxide penetration, decarburization, etc., can be developed during manufacturing. These surface defects impact the fatigue strength in various ways.
The impact of the decarburized layer depth on the fatigue life of a forged powder metal connecting rod is the focus of this work.
Several connecting rods were submitted to a Weibull test at the same loading pattern. After the fatigue tests, the connecting rods were divided into groups with different decarburized layer depths. Both Maximum Likelihood Estimates (MLE) and Rank Regression (RR) techniques were used to analyze test results from all the groups obtained. Several methods were applied in order to test data sets for significant differences.
Considering the results of this study, it can be said that decarburized layer depths up to 0.400 mm do not significantly impact the fatigue life of a forged powder metal connecting rod. For decarburized layer depths higher than 0.400 mm, the fatigue life decreases.