Fraunhofer Institute for Material and Beam Technology IWS- In a recent IWS research project, laser multi-pass narrow-gap welding is being investigated for use in nickel-base alloys. The aim of the research is the use of this innovative joining technology in the field of thick-walled components in energy-efficient and resource-saving high-temperature processes (700 ° C power plant).
- The present thick-walled samples require an exact and targeted preparation as well as a joining interfaces’ surface characterization.
- For the mechanical characterization of welded joints, defined sample geometry is used in conjunction with high-frequency fatigue testing. Thus, internal material or weld irregularities can be activated as the starting point for fatigue cracks.
- The results of the fatigue tests show a direct correlation between size and shape of irregularities and the tolerable load amplitude (Murakami – concept).