Fraunhofer Institute for Mechanics of Materials IWMAdditive manufacturing (AM) opens up new possibilities for the production of highly stressed metal components and complex geometries – especially for small and medium-sized enterprises (SMEs). However, a key challenge lies in the inadequate surface quality of additively manufactured components, which severely limits their fatigue strength. The “AM Surface” research project specifically investigated how mechanical post-treatment processes – such as shot peening, roll finishing, and smoothing – can contribute to the targeted improvement of component properties. The methods and findings developed pave the way for broader industrial application of additive manufacturing, including in safety-relevant areas.
Mechanical surface treatment of additively manufactured metal components for targeted improvement of fatigue strength
Completed research project
Project description
Additive manufacturing (AM) is becoming increasingly important for the production of highly stressed metal components, as it enables the efficient manufacture of complex geometries while avoiding high levels of machining. In addition to geometric freedom, AM offers great innovation potential, especially for SMEs – in particular through the possibility of manufacturing individual components quickly and resource-efficiently without expensive tools. Despite acceptable strength values, however, AM components often have insufficient surface quality when untreated. Surface-near defects act as crack initiators and lead to premature failure of the component.
Mechanical surface treatment processes such as shot peening, roll hardening, and smoothing offer enormous potential for increasing the fatigue strength of additively manufactured components by introducing compressive residual stresses into the edge zone of a workpiece and compacting and smoothing the surface layer. While there are a limited number of studies on shot peening of AM components, the effect of roll hardening and smoothing on the targeted increase of fatigue strength has not yet been systematically researched.
The “AM Surface” project showed that surface post-treatment can be used to specifically compact surfaces and introduce residual stresses, thereby improving component properties and significantly increasing service life. In addition to experimental investigations, another focus was on the development of calculation and design methods suitable for SMEs. An easy-to-use procedure for component design was developed based on the widely used FKM guidelines, depending on the process parameters of the post-treatment methods.
Fraunhofer IWM subproject:
- Systematic investigation of the effects of hard rolling on the internal stress distribution in AM components
- Experimental determination of fatigue strength as a function of post-treatment parameters
- Development and validation of a calculation and design method for predicting component life, taking into account post-treatment processes based on the widely used FKM guidelines
- Derivation of practical evaluation guidelines for industrial application
Transfer of project results to the following Fraunhofer IWM R&D services for companies:
- Targeted increase in the fatigue strength of highly stressed AM components through customized surface treatment (also for highly stressed and safety-relevant components)
- SME-friendly design and evaluation methods for optimized surface treatment and precise service life assessment based on widely used FKM guidelines
- Numerical simulation and service life assessment of mechanically post-treated AM components
- Experimental characterization and quality assurance of post-treated AM components – e.g., via residual stress analyses and microstructure investigations
- Consulting and support for the introduction of post-treatment processes in SMEs, including process optimization and parameter studies
