Effect of Support Height on Microstructure and Mechanical Properties of Selective Laser Melting Ti–15Mo Alloy

In this research, for the first time, the Ti–15Mo alloy generated via selective laser melting (SLM) with many different support heights was examined. With the increase of the support height, the risks of forming microcracks and small holes increase while the ductility of the sample decreases. The grain sizes of the samples decrease with an increase in support height because of the more efficient heat dissipation rate during the SLM process. The average grain sizes of the samples are 36.95 ± 0.7 μm (5 mm-sample I), 35.24 ± 0.7 μm (10 mm-sample II) and 33.91 ± 0.7 μm (15 mm-sample III), respectively. As the support height increases, the intensity of (111) texture increases and the misorientation angles gradually decrease. The ultimate tensile strength, yield strength and ductility of the three samples are 970 ± 13 MPa, 769 ± 12 MPa and 9.78% ± 1.5% (sample I), 1051 ± 11 MPa, 932 ± 11 MPa and 7.17% ± 2% (sample II), 1123 ± 14 MPa, 1089 ± 9 MPa and 5.4% ± 1.4% (sample III), respectively. The decrease in grain size, increase in dislocation density and enhancement of the (111) texture are all conducive to achieving the higher strength.