| Abstract: | Improvement in Fatigue Properties by Means of Deep Rolling Deep rolling has an almost 60 years old tradition and today it is an important process especially for automobile structural parts. The development of deep rolling was greatly influenced by the Institute of Material Science of the Technical University in Darmstadt. After a short historical review the general mechanism of mechanical strengthening is discussed. Then new experimental results on ductile cast irons and a case hardened steel are given. The improvement in fatigue strength of notched specimens out of these materials is even higher than that observed on steel in previous investigations. However the experiments also indicate that mechanical strengthened parts obviously have no real fatigue limit. Measurements of crack propagation on nodular cast iron specimens show that the propagation rate of cracks in the notch root is extremely reduced by compressive residual stresses. However no real crack arrest could be observed. |
