Improvements in mechanical property and corrosion resistance of Ti-6.5Al-2Zr-1Mo-1V fabricated by laser powder bed fusion using cost-effective modified hydride-dehydrided powder

Due to higher mechanical properties and shorter fabrication time, Ti-6.5Al-2Zr-1Mo-1V (TA15) fabricated by laser powder bed fusion (LPBF) is gaining increasing attention. However, the high cost of raw powder limits its wide application. In this study, TA15 is fabricated by LPBF using cost-effective modified HDH powder (LPBF-ed modified HDH). Microstructure, mechanical properties, and corrosion resistance of the fabricated sample are investigated and compared systematically with sample fabricated by LPBF using gas atomization (GA) spherical powder (LPBF-ed GA). The result shows that both two samples can achieve full density at the optimized process parameters and consist of alpha ' phase. But compared with LPBF-ed GA sample, the volumetric energy density (VED) of LPBF-ed modified HDH decreases about 60 % (41.15 vs. 94.65 J/mm3), which makes the LPBF-ed modified HDH sample exhibit finger grain size (decreasing from 0.231 mu m to 0.129 mu m). Such differences together with different interstitial element content result in LPBF-ed modified HDH samples exhibiting higher mechanical properties and corrosion resistance compared with LPBF-ed GA sample, namely tensile strength and elongation improves about 10 % (from 1286.1 MPa to 1353.7 MPa) and 100 % (from 5.8 % to 11.2 %), respectively, while corrosion current density (Icorr) and passivation current density (Ip) reduces about a half (from 2.98 x 10- 8 A/ cm2 and 4.07 x 10-6 A/cm2 to 1.03 x 10- 8 A/cm2 and 2.54 x 10-6 A/cm2, respectively). Furthermore, the cost analysis result indicates that the cost of modified HDH powder was reduced by 60 % compared with GA powder (50 vs. 120 $/kg). Cost-effective raw materials together with a good combination of tensile strength and elongation and excellent corrosion resistance make LPBF-ed modified HDH parts exhibit broad application prospects, especially in the fields of aviation and maritime.