Influence of laser polishing on the material properties of aluminium L-PBF components

Markus Hofele*, André Roth, Patrick Hegele, Tim Schubert, Jochen Schanz, David K. Harrison, Anjali K.M. De Silva, Harald Riegel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
3 Downloads (Pure)

Abstract

In this study, the influence of laser polishing on the microstructural and mechanical properties of additively manufactured aluminium AlSi10Mg Laser Powder Bed Fusion (L-PBF) parts is analysed. The investigation is carried out on a 5-axis laser cell equipped with 1D Scanner optics driven by a solid-state disc laser at a wavelength of 1030 nm. Laser polishing is performed with pulsed or continuous laser radiation on samples in the initial L-PBF state or after stress relief treatment in a furnace. The metallurgical investigation of the remelting zone with a depth of 101–237 µm revealed an unchanged and homogeneous chemical composition, with a coarsened α-phase and a changed grain structure. The hardness within the remelting zone is reduced to 102–104 HV 0.1 compared to 146 HV 0.1 at the L-PBF initial state. Below the remelting zone, within the heat affected zone, a reduced microhardness, which can reach a thickness up to 1.5 mm, occurs. Laser polishing results in a reduction in residual stresses and resulting distortions compared to the L-PBF initial state. Nevertheless, the re-solidification shrinkage of the polished surface layer introduces additional tensions, resulting in sample distortions well above ones remaining after a stress relieve heat treatment of the initial state. The mechanical properties, analysed on laser polished flat tensile specimens, revealed an increase in the ultimate elongation from 4.5% to 5.4–10.7% and a reduction in the tensile strength from 346 N/mm² to 247–271 N/mm² through laser polishing. Hence, the strength resulting from this is comparable to the initial L-PBF specimens after stress relieve heat treatment.

Original languageEnglish
Article number750
Number of pages28
JournalMetals
Volume12
Issue number5
DOIs
Publication statusPublished - 27 Apr 2022

Keywords

  • laser polishing
  • material properties
  • residual stress
  • distortion
  • hardness
  • tensile strength
  • additive manufacturing
  • selective laser melting (SLM)
  • aluminium AlSi10Mg
  • surface remelting
  • Laser Powder Bed Fusion (L-PBF)

ASJC Scopus subject areas

  • Materials Science(all)
  • Metals and Alloys

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