Build location effect on the single-track pore characteristics formed with the laser powder bed fusion process

The presence of location-specific property in the laser powder bed fusion (LPBF) process impedes the part qualification desired for different applications. This study uses keyhole porosity as a parameter to evaluate the variability induced by the horizontal build location and height. Single tracks with 195 W laser power and four scan speeds: 200 mm/s, 400 mm/s, 600 mm/s, and 800 mm/s are fabricated inside hollow cylinder samples. The samples are fabricated at the center and four corners of the build platform. Besides, the same models are also fabricated at different build heights of 6.60 mm, 56.6 mm, and 107 mm at each location. Micro-CT is used to measure the pore characteristics such as the number, volume, diameter, and depth of the pores formed inside the single tracks. The results show that the build location has a noticeable effect on the porosity, with the horizontal location being more significant than the build height. The pore number and volume are the highest for the single tracks formed at a corner away from the build chamber window and towards the dispenser. Moreover, micrographs of the longitudinal section of the single tracks are acquired to study 2D pore characteristics. The comparison between the micrographs and micro-CT suggests that for the same pore the CT measurement gives slightly smaller pore sizes compared to the micrographs. (C) 2020 Society of Manufacturing Engineers (SME). Published by Elsevier Ltd. All rights reserved.

Automated summary

The study shows that the build location significantly affects porosity in laser powder bed fusion, with the horizontal location being more important than the build height. Single tracks formed at a corner away from the build chamber window and towards the dispenser have the highest pore number and volume.