Comparative study of Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy fabricated by selective laser melting and laser metal deposition

In the present study, Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy, one of the widely used near-alpha titanium alloys in the field of aeronautical and astronautical, was fabricated by two lasers additive manufacturing technologies, namely selective laser melting (SLM) and laser metal deposition (LMD). Microstructure, mechanical property, productivity, and forming cost of fabricated TA15 samples by these two processes were compared systematically. The results showed that the microstructure of the SLM-ed and LMD-ed samples exhibited differences in terms of crystallographic orientations, grain boundaries, and grain sizes, which was mainly attributed to the distinct thermal histories associated with each process. Such differences resulted in the LMD-ed sample presenting anisotropy, lower tensile strength, and higher elongation compared to the SLM-ed sample. Cost analysis indicated that the forming cost per unit volume of the LMD-ed sample was about half that of the SLM-ed sample. This difference was primally due to the higher productivity of the LMD process (226.1 cm3/h) compared to the SLM process (8.8 cm3/h), as well as the lower power cost of the powder materials (60 vs. 100 $/kg). Furthermore, the forming maximum volume of the LMD process (-30.38 m3) was about 28 times than that of the SLM process (-1.08 m3). In conclusion, this study provides a detailed comparison between SLM-ed and LMD-ed TA15 samples. The findings can act as a reference for selecting optimized fabrication methods for practical industrial applications, taking into consideration specific mechanical properties, forming size, and cost requirements.