Effect of process parameter optimization on morphology and mechanical properties of Ti6Al4V alloy produced by selective laser melting

Ti6Al4V alloy has been found extensive use in various sectors like aerospace, medical service, national defense, and industrial automation. In this study, Ti6Al4V alloy was obtained by selective laser melting (SLM) to investigate the effects of different process parameters on the quality, relative densities, and morphology of the parts produced, as well as the influence of linear energy density on the quality of these parts. The results of the research show that the optimal forming parameter is attained when the laser power ranges from 190 to 250 ​W, the scanning speed ranges from 600 to 720 ​mm/s, the overlap rate is 50 ​%, and the relative density of the specimens reaches up to 99.3 ​%. Accordingly, the linear energy density is in the range of 0.26–0.36 ​J/mm. Vickers hardness and tensile strength tests were performed for the samples, the mechanical properties of the samples exhibit the highest value of 300 ​± ​1.5 HV and tensile strength of 1180 ​MPa. By analyzing the experimental results, it can be observed that there is a direct correlation between the linear energy density and the quality of the forming process. When the linear energy density is excessively high, the parts are porous and defective. Conversely, the titanium alloy does not melt sufficiently, which makes it difficult to complete forming. According to the above results, the forming performance of the parts is improved by optimizing the process parameters, and the waste of materials is reduced. Meanwhile, a feasible reference for Ti6Al4V alloy by SLM is provided.