Effects of powder compression and laser re-melting on the microstructure and mechanical properties of additively
manufactured parts in laser-powder bed fusion
Achieving good surface profile and low levels of porosity are prime challenges in the Laser-Powder Bed Fusion (L-PBF) additive manufacturing technique. In order to optimise these properties, post-processing is often required. However, the compression of powder spread on the build plate and re-melting of each build layer during the L-PBF process could address these challenges. In this study, the effect of different powder compression ratios and laser re-melting regimes on the density, microstructure morphology, surface profile and mechanical properties of L-PBF produced parts were investigated. Two different metal printers with same laser processing parameters were used to fabricate 10 x 10 x 10 mm3 stainless steel 316L samples. To examine the impact of compression ratio and layer re-melting, one set of samples was prepared with three different compression levels for each layer, and the second set of samples either a single or double set of laser passes for each layer. The Volumetric Energy Density (VED) range examines was from 26.7 J/mm3 to 80 J/mm3. Density, hardness, elastic modulus, microstructure, and surface profiles of the printed samples were characterized. A 3% increment in density and a 50% reduction in the surface roughness were achieved using a laser double pass over each layer. The results demonstrate, by applying different powder compression ratios onto the powder bed and by re-melting each layer, that the density, surface roughness, and the elastic modulus of the produced samples can be improved.
Metadata
Item Type:
Article (Published)
Refereed:
Yes
Additional Information:
Article number: 100264
Uncontrolled Keywords:
Laser powder bed fusion; Additive manufacturing; Powder compression; Laser re-melting; Nano-indentation; Archimedes density