Hybrid joining of ultra high strength steel to aluminium with Friction Stir Welding
Purpose and goal
The combination of ultra high strength steels (UHSS) and aluminium is expected to play a large role in the vehicles of the future. Today´s joining technology is associated with large difficulties when aluminium is joined to the UHSS of tomorrow. In the project we test the hypothesis that friction stir welding can be used to create high performance overlap joints between aluminium and UHSS. Trials on one AA5000 alloy and a DP800 steel show very good results with robust mechanical properties.
Results and expected effects
The project proposes an innovative joining method for tomorrows combination of aluminium and ultra high strength steels. This is well in line with the road map targets of the FFI programme regarding robustness, productivity, flexibility and cost efficiency.
Approach and implementation
In this application the friction stir tool penetrates the aluminium part and rubs towards the steel part. In this way high wear rates inside steel can be avoided. Trials on a AA5000 and a DP800 ultra high strength steel show good and reproducible mechanical properties of the overlap joint. The joint is created by a controlled chemical reaction in the interface layer between the steel and the aluminum.