Review on volumetric energy density: influence on morphology and mechanical properties of Ti6Al4V manufactured via laser powder bed fusion

Abstract

Various laser powder bed fusion (LPBF) process parameters must be considered as they can independently affect the properties of end-product. However, many studies simply examine one or two LPBF process parameters. Laser power, scan speed, scan spacing, and layer height are the four primary LPBF process parameters that contribute to volumetric energy density (VED) used in LPBF. VED is often used as an optimization metric for LPBF process parameters, because it takes all four major parameters into consideration. Thus, this paper focuses on the effect of VED on the morphology and properties of part, and also discusses on the interrelationship between all four parameters. Common range used for each parameter is 70–400 W for laser power, 70–1800 mm/s for scan speed, 50–140 µm for scan spacing, and 20–50 µm for layer height. It can be seen as the VED increased, the microstructure of as-built titanium alloy Ti6Al4V components exhibited smaller α’ martensite size and larger columnar β grain. High VED can also reduce porosity and defect formation, which will help in increasing part density. The lowest surface roughness reported for LPBF Ti6Al4V is 4.91 µm. Meanwhile, the maximum microhardness obtained is 443 HV and the highest tensile strength achieved is 1400 MPa. The VED used for studies that obtained these results are in the range of 55–65 J/mm3. Thus, it can be concluded that the most suitable VED for LPBF printing of Ti6Al4V is around 55–65 J/mm3.

Innovative Fabrication Design for In Situ Martensite Decomposition and Enhanced Mechanical Properties in Laser Powder Bed Fused Ti6Al4V Alloy

“…Therefore, this study highlights the crucial role of optimizing process parameters, including gap size, in achieving high-quality LPBF-fabricated parts. Superior mechanical properties can be attained by eliminating residual porosity and reducing pore size, making it an important consideration to note [70,71].…”

Understanding the hot isostatic pressing effectiveness of laser powder bed fusion Ti-6Al-4V by in-situ X-ray imaging and diffraction experiments

“…Numerous studies on the process optimization have been conducted. They aimed at reducing the amount and volume of defects resulting from PBF-LB 3 , 7 , 8 . These optimization efforts also include in-situ synchrotron X-ray imaging studies conceived to understand the mechanisms of defect formation and the melt pool dynamics during manufacturing 5 , 9 .…”

Surface morphology and dimensional accuracy of additively manufactured Ti-6Al-4V alloy: Effect of variable scanning speed with constant laser power in widespread energy density

“…It is generally calculated with the use of laser power (LP; P ), scanning speed (SS; v ), hatch spacing ( h ) and layer thickness ( t ) as indicated by the following equation:Various researchers have attempted to improve better surface quality through variations in energy density values. 1,7–13 However, the scattered energy density between higher and lower values over the surface roughness revealed the energy density as a whole is not only responsible but the process parameters which decide the energy density account for the achievement of the quality of the part. Variations in LP and SS combinations lead to differences in surface quality.…”