Abstract
Recently, automobile companies re directing their efforts toward lowering mileage, making compact and etc. of automobile engines for the economical and environmental reasons. Therefor, weight reduction of engine parts, such as forged connecting rods is most important item. To increase fatigue limit of the connecting rods, the following four characteristics to be developed : a)Decarburized depth b)Hardness c)Residual stress d)Notch (surface flaw, surface roughness). So, the authors investigated influence of residual stress and surface flaw upon fatigue limit of forged connecting rods. The main result shows as follows : Fatigue limit of the connecting rods in proportional to the surface residual stress.
