Spot Welding & Processing
The spot welding group conducts the research of refill friction stir spot welding (refill-FSSW), which is also known as friction spot welding. This is a novel solid-state spot welding process developed and patented by Helmholtz-Zentrum Hereon GmbH. Compared to the conventional fusion spot welding and friction stir spot welding process, it offers many advantages such as improved surface quality, enhanced mechanical properties, environment compatibility, ease of automation, etc.
- Refill-FSSW process development for similar and dissimilar material combinations
- Metallurgical characterization of microstructure based on SEM, EBSD, TEM, etc.
- Mechanical properties assessment (lap shear, cross-tension, peel, fatigue, etc.)
- Numerical simulation of welding process by thermal-mechanical analysis, stress/strain and crack propagation analyses during mechanical properties tests
- Weld corrosion resistance ability test
- Repair of defects such as crack, porosity, hole of workpiece
The spot welding group has acquired and held the international leading position for refill-FSSW due to the powerful hardware, talented researchers and intensive cooperation with other research institutions and industrial partners worldwide. We are glad to accept the technical and scientific challenges concerned on refill-FSSW.
Photo: Hereon/Christian Schmid
Currently, a clear tendency to rivet - free and energy - efficient technologies becomes apparent to join similar and dissimilar materials particularly used in the transportation industry. The goal is to reduce weight to comply with increasingly strict environmental requirements.
At Helmholtz-Zentrum Hereon, a solid state joining process called friction spot welding has been developed as an alternative to conventional fusion welding techniques that are limited with regard to material combinations and joint strength, in particular for lightweight metals. Especially the possibility to produce dissimilar joints predestines the friction spot welding for the application to produce high strength, environmentally friendly and lightweight joints of metallic materials.
The friction spot welding, also known as refill friction stir spot welding, is a friction based joining technique to create spot like joints without filler material with superior mechanical performance and surface quality. Since bonding and processing take place in the solid state all metallurgical reactions involved in melting and solidification are avoided in similar joint configuration, resulting in defect free joints with superior properties.
This technique has successfully been used to produce dissimilar aluminium/steel, aluminium/magnesium, aluminium/copper, aluminium/titanium, magnesium/titanium and magnesium/steel joints. Similar joints of different aluminium and magnesium alloys show superior properties as well.
At Helmholtz-Zentrum Hereon, we are exploring and developing the possibilities of friction spot welding further. The research is focused on analysis and characterization of process - properties as well as structural analysis of welded components. Additionally simulation tools are applied to support the investigations. By using the friction spot welding as a keyhole closure method, new fields of application are developed.