STIFFCRANK - Advanced laser surface hardening of microalloyed steels for fatigue enhancement of automotive engine components
Cooperation: AIMEN Technology Centre, Vigo, Spain; Sidenor Investigacion y Desarrollo S. A., Bilbao, Spain; Lulea University of Technology, Lulea, Sweden
The need for light, small and powerful components in engine applications results from the extremely increased requirements with regard to reduction of CO2 emissions. As a consequence of downsizing, extreme challenges for the materials and mechanics of components arise - especially in case of the crankshaft.
The expectations on wear resistance and the fatigue performance of these precision parts are more than challenging. Employing induction hardening technology and deep rolling, respectively, surface zones can be partially hardened in a targeted manner according to the requirements. As part of the European joint project “STIFFCRANK”, a new laser-based process for the surface treatment of steel is to be developed in order to ensure safe and endurable use of crankshafts. The focus here is on optimizing service life and reliability as well as qualifying the process for components in the mobility sector. These goals are to be achieved on the basis of a better understanding of the relationships between residual stresses close to the surface and the microstructural conditions that arise through laser-based surface hardening. In addition, the effects on the service life of crankshafts under fatigue loading are examined in detail. Finally, guidelines for the optimization of the production of highly stressed components are to be created, taking into account both the steel grades used and the laser processes employed. Particular attention is paid to the analysis and evaluation of the internal stress states induced in the components. It is very important to scientifically assess the relationship between the microstructure evolution, the hardness distribution and the inherent stress fields.