YMPMAT - Filler metal with nanoparticles for welding of aluminium-alloys

Important results from the project

The pre-study aimed at evaluating the possibility to reduce the risk for solidification cracking in TIG and laser welding of, a normally difficult-to-weld material such as 7075 aluminium alloy, by adding nanoparticles to the weld in order to refine the grain size in the weld metal. TiC in different size (from nano- to microparticles) were mixed into the 7075 aluminium alloy by using Friction Stir Welding and then welding with bead-on-plate technique. A clear reduction in grain size and more equiaxed grains was achieved. Welding could be performed without solidification cracking.

Expected long term effects

The technique of using nanoparticles to improve the weldability of normally difficult-to-weld aluminum alloys (in this case a 7xxx alloy) seems positive and could potentially increase the use of these lightweight materials. The way to add nanoparticles is difficult and costly and would need to be improved / simplified.

Approach and implementation

Good expertise within the consortium has been very valuable. The work has bee divided in: Propose suitable nano- and microparticles based on thermodynamic calculations - KTH Prepare samples and produce an area in the base metal with nano- or microparticles (An area that will be welded by autogeneous TIG and laser. The area is already filled with particles to simulate use of a matching filler wire with nano- or microparticles) - Swerim/ESAB Perform TIG and laser welding - ESAB/Swerim Evaluate samples before and after welding - Swerim/Hydro Meetings and discussions - All