Joining of AA1100–16 vol.-%B₄C metal matrix composite using laser welding and friction stir welding

Abstract

This work investigated the weldability of AA1100–16B₄C (vol.-%) metal matrix composite using laser welding and friction stir welding (FSW). The microstructure and mechanical properties of joints produced by two welding techniques were compared. For laser welding, a large amount of brittle needle-like phases, together with some residues of B₄C particles were observed in the fusion zone of the joint. The use of Ti filler can improve the microstructure and increase the joint efficiency from 63 to 75%. On the other hand, the FSW, being a solid state welding technique, was interesting as it minimised the formation of brittle intermetallic phases. In addition, the breakage of B₄C particles and the grain refinement of the matrix were observed in the weld zone. The FSW joints show superior mechanical properties than the laser welded joints. Up to 100% joint efficiency can be achieved by FSW for annealed AA1100–16B₄C materials.

Ce travail a examiné la soudabilité du composite à matrice métallique AA1100-16B₄C (% en vol) en utilisant le soudage au laser et le soudage par friction-malaxage (FSW). On a comparé la microstructure et les propriétés mécaniques des joints produits par les deux techniques de soudage. Pour le soudage au laser, on a observé une grande quantité de phases fragiles en forme d'aiguille ainsi que des résidus de particules de B₄C, dans la zone de fusion du joint. L'utilisation de métal d'apport de Ti peut améliorer la microstructure et augmenter l'efficacité du joint de 63 à 75%. D'un autre côté, le FSW, une technique de soudage à l'état solide, était intéressant puisqu'il minimisait la formation de phases intermétalliques fragiles. De plus, on a observé, dans la zone de soudure, la rupture des particules de B₄C et l'affinement de grain de la matrice. Les joints du FSW montraient des propriétés mécaniques supérieures aux joints soudés au laser. On peut obtenir une efficacité du joint jusqu'à 100% par FSW pour les matériaux recuits d'AA1100-16B₄C.

Keywords:

• Laser welding
• Friction stir welding
• Metal matrix composites
• Microstructure
• Mechanical properties
• Intermetallic phases

The authors would like to express their great appreciation for the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC), Rio Tinto Alcan and NRC-Aluminium Technology Centre through the NSERC Industrial Research Chair in Metallurgy of Aluminium Transformation at the University of Quebec at Chicoutimi. They also gratefully acknowledge the technical support provided at the NRC-Aluminium Technology Centre, especially Dr Amira, Mrs Grégoire, Mr Larouche and Mr Patry for their precious contributions.

Notes

This paper is part of a special issue on Advances in High Temperature Joining of Materials