Effect of Al–5Ti–1B grain refiner on microstructure and properties of arc-additive-manufactured Al–Mg alloy

Abstract

In this study, a strip-shaped Al–5Ti–1B grain refiner was employed to produce Al–Mg alloy using cold metal transfer arc additive manufacturing. The microstructure and mechanical properties of the straight-wall samples (SWSs) were analyzed. The results indicated that the Al3Ti phase occurred in SWS with Al–5Ti–1B, and acted as heterogeneous nucleation sites during solidification. Formation of Al3Ti particles led to the transformation of the columnar grains between the layers into equiaxed grains and refined the grains at the center of the layers. Furthermore, the Al3Ti particles increased the fraction of low-angle grain boundaries by 8.2%. In addition, the anisotropy in mechanical properties (i.e. tensile strength and elongation) was reduced significantly. Also, the low hardness zone between the layers was eliminated. Thereby, improving the mechanical properties of the additive-manufactured Al–Mg alloy samples.