Effect of scanning strategies on the microstructure and mechanical properties of Ti–15Mo alloy fabricated by selective laser melting

Abstract

The phase composition, dislocation density and crystallographic texture associated with the mechanical properties of Ti–15Mo alloys fabricated by selective laser melting (SLM) with various scanning strategies have been systematically studied in this work. The weak α′ phases were formed in the samples besides the β phases regardless of what types of scanning strategies were used owing to the oxygen residue in the powders and the gaps of powders. The texture of Ti–15Mo alloy can be altered with different scanning strategies: When the scanning rotation angles are changed from 0° to 90°, the texture orientation is transformed from <101> to <111>. The rotation between the layers can break the columnar grains into fine grains and the grain size are 0.83 μm (0°-sample I), 0.49 μm (45°-sample II), 0.61 μm (90°-sample IIII) and 0.55 μm (chessboard-sample IV), respectively. The tensile strength of the samples Ⅰ, Ⅱ, Ⅲ and Ⅳ are 867.5 ± 4.7 MPa, 898.6 ± 7.3 MPa, 839.8 ± 5.1 MPa and 1001.1 ± 10.9 MPa, respectively. The contributions of the high strength to the Ti–15Mo alloy fabricated by SLM are stemmed from the comprehensive results of the phase composition, grain size, density dislocation and crystallographic texture.