Understanding the microstructure and mechanical properties of Ti-6Al-4V and Inconel 718 alloys manufactured by Laser Engineered Net Shaping

Laser‐Based Additive Manufacturing Technologies for Aerospace Applications

“…[123] A typical lamellar cast Ti-6Al-4V microstructure consists of a hexagonal closepacked (HCP) α phase and body-centered cubic (BCC) β phase, as shown in Figure 13. [118] Similarly with an SLM process, the martensite α' structure was observed, having a reduced plate width with an increased scan speed as shown in Figure 15. Depending upon the location of the build, laser power input, and other process parameters, the cooling rate and heat treatment history (each layer, except the top layer, is subjected to reheating from the subsequent passes), the size, shape, and distribution of α and β, or acicular α 0 can vary as shown in Figure 14.…”

“…[117] The resulting microstructure resembles that of Figure 9. [38,118] In the DED process, similar defects can occur if powder is used. Reproduced with permission.…”

“…A comparison with the tensile and yield strengths as well as the ductility for different AM processes involving Ti-6Al-4V is shown in Figure 18. [118] Copyright 2019, Elsevier. Electron backscatter diffraction images of high-power-fabricated LENS Inconel 718 in a) short age (732˚C for 4 h), b) double age (720˚C for 8 h þ620˚C for 10 h), and c) homogenization, solutioning, and double aging (1093˚C for 1 h, air cooled, solutioning at 960˚C for 1.5 h, and double age).…”

“…[37] On the other hand, IN738 exhibited a different trend in which the ductility increased by nearly a factor of 3 compared with the wrought sample. [118] Copyright 2019, Elsevier. IN625 specimens generated by electron beam melting (EBM) in the as-fabricated condition have equivalent ductility to the wrought product but 9% lower yield strength.…”

“…IN625 specimens generated by electron beam melting (EBM) in the as-fabricated condition have equivalent ductility to the wrought product but 9% lower yield strength. [118] Copyright 2019, Elsevier. [99] The microstructure after the AM process usually assumes similar features as those found in the as-welded state; often a post-AM process thermal treatment is Figure 14.…”