Characterisation of welded joints produced by FSW in AA 1100–B 4 C metal matrix composites

Abstract

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 ∼20% and the grain size from 15 to 5 μm 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 ∼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⁻¹ does not influence the tensile properties and the particle size distribution in the nugget.