Design of a novel scanning strategy for formation of extremely strong textures in hexagonal materials through laser powder bed fusion

While crystallographic texture control in cubic metals via laser powder bed fusion (LPBF) has been demonstrated in recent years, achieving such control in hexagonal metals remains a significant challenge. In the present work we present a novel route for the development of a very strong texture in a hexagonal close-packed (hcp)-structured Mg alloy through LPBF. It was achieved by employing reciprocal scanning with a 120° rotation between layers, aligning with the symmetry of Mg’s hcp crystal structure. This unique scanning strategy was designed through computational simulation of the heat flux in the melt pool and consideration of the six-fold rotational symmetry along the [0001] axis of the hcp structure. The texture formation was driven by preferential < 11 2 ¯ 0 > crystal growth along a direction inclined at approximately 60° to each scanning direction (0°, 120°, and 240°). The LPBF-fabricated specimens showed an anisotropic stress–strain responses in compression test owing to the crystal orientation-dependent selection of operative slip systems, similar to the behavior in a Mg single crystal. These findings highlight the potential in optimizing the scanning strategy by reflecting the symmetry of the crystal structure. This is particularly crucial for LPBF manufacturing non-cubic metals with prominent textures.