20th International Forgemasters Meeting - IFM 2017

Current requirements for internal combustion engines are becoming more and more demanding. Therefore, new generation of crankshafts needs to reduce in size and sustain higher loads. This dramatically increases the stresses in the components, making the fatigue strength enhancement a necessity. Sidenor understands that this improvement should arrive as a result of the combination of two different lines which have proved to be efficient separately: applying surface treatments (such as deep rolling) and improving material cleanliness. Deep rolling has been developed for fillet areas in solid-forged crankshafts for marine and energy applications. In addition to the elimination of micro notches and improvement of surface roughness quality, this cold deformation process produces a deep layer of compressive residual stress in the surface of the component, which behaves as a natural barrier for crack propagation. The other upgrade, seizing the advantage of a process integrated plant, consists of achieving extremely high cleanliness in the steel for these applications. By having less and smaller non-metallic inclusions, a higher fatigue strength is obtained. In order to confirm the superior behavior of material treated according to mentioned techniques, several tests have been performed, from which it has been shown the great advantage that combining them would imply, so that engine manufacturers may continue with their size reduction process.