Direct laser fabrication and microstructure of a burn-resistant Ti alloy

Microstructures of laser-deposited Ti–6Al–4V

“…Some research had been done on DLF which showed that important features of the process such as build height and width, residual stress, microstructure are strongly dependent on the DLF processing parameters including laser power, laser scanning velocity, z-axis increment (deposit direction), powder feed rate, etc [1][2][3][4][5][6][7][8][9][10]. Much of the previous work has been focused on equipment and software development and limited research has been reported on materials such as Ti-6Al-4V [5,7].…”

Laser-aided manufacturing technologies; their application to the near-net shape forming of a high-strength titanium alloy

“…In this instance, there was no evidence from either the tensile testing or from the fracture toughness work of a poor substrate-deposit bond. The strong interface is thought to be associated with the preparation of the substrate, prior to deposition, where a 'melt-back' run, scanning the laser across the surface without any powder deposition, was undertaken [7].…”

Direct Laser Fabrication of Ti-25V-15Cr-2Al-0.2C (wt pct) Burn-Resistant Titanium Alloy

“…High laser power at 1148 W causes the precipitates to be longer ( Figure 6(d)) and thicker (5 by 1 lm) than those (2 by 0.8 lm) built ( Figure 6(a)) by low laser power 755 W. However, there is no obvious difference in the volume fraction (16 pct). [11] Comparing Figure 7 with Figure 6, annealing at 973 K (700°C)/2 hours in argon has no obvious effect on the particles size and distribution. Hot isostatically pressing at 1203 K (930°C)/103 MPa/4 hours has a significant effect on the coarsening of the precipitates along grain boundaries and the formation of precipitate-free zones adjacent to these boundaries because the titanium carbides diffuse toward high energy boundaries, as indicated by arrows in Figure 8(a).…”

“…The overall microstructure of direct laser fabricated Ti-25V-15Cr-2Al-0.2C burn-resistant titanium alloy, using laser powers up to 516 W, has been characterized in detail by Wu et al [10,11] At low powers, equiaxed grains containing approximately 16 pct volume fraction of precipitates are found throughout most of the height of the samples with elongated equiaxed grains at the substrate/sample interface. Increases in laser power from 222 W to 516 W have little effect on the overall morphology of the Ti-25V-15Cr-2Al-0.2C alloy, but the precipitates become both longer and thicker.…”