Abstract
In order to lighten the weight of connecting rods, which are put into service with the surface as forged, mechanical properties, especially fatigue strength of the forged surface should be improved. In powder forged material, surface defects such as decarburized layer, surface roughness, and non-sintered area(NSA) are observed. This NSA, peculiar to this material, plays the most important role in determining the mechanical properties.
In order to develop the optimum strengthening process, the authors focused on this NSA and microscopically observed the microstructure and fractography to quantify the defect, using the ratio of NSA versus the cross sectional area. In addition, the effect of manufacturing conditions on the NSA production mechanism was quantitatively analyzed. As a result, NSA are caused by particle interface oxidation, thought to occur before forging via open-pores.
