Characterisation of welded joints produced by FSW in AA 1100-B4C metal matrix composites

The feasibility of friction stir welding for joining AA 1100 based metal matrix composites reinforced with B4C particulate is studied for 16 and 30%B4C volume concentrations. For both composites, friction stir welding has a significant influence on the particle size distribution and the matrix grain size. For the 16% composite, the average particle size decreases after welding by similar to 20% and the grain size from 15 to 5 mm as measured in the weld nugget. Tensile testing of welded joints showed up to 100% joint efficiency for both annealed AA 1100-16%B4C and AA 1100-30%B4C composite materials. However, if the ultimate tensile strength values of all the studied composites are similar at similar to 130 MPa, then the weld ductility is higher for the annealed materials. Furthermore, it was observed that varying the welding speed between 100 and 275 mm min 21 does not influence the tensile properties and the particle size distribution in the nugget.