Surface integrity of SLM manufactured meso-size gears in laser shock peening without coating

Sunil Pathak, Marek Böhm, Jan Kaufman, Jaromír Kopeček, Sanin Zulić, Ondřej Stránský, Ashish Shukla, Jan Brajer, Libor Beránek, J. Radhakrisnan, Danijela Rostohar, Tomáš Mocek

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)
42 Downloads (Pure)


The present work aimed to improve the surface integrity of the selective laser melting manufacturing (SLM) manufactured 10 mm sized meso gears using the unconventional Laser Peening without Coating (LPwC) technique. To accomplish LPwC on meso gears low energy in the range of 200 mJ to 1000 mJ at 10 Hz were applied underwater in the gear root and fillet gap generating significant surface compressive residual stresses (from +73 MPa to −298 MPa). Besides the surface, residual stresses, average surface roughness (Ra), arithmetical mean height (Sa) and parameters of the material ratio curve were also considered as a part of the study. Notable improvement was achieved in Sa, as it improved over 50 % while considerable improvement in Ra and the material ratio curve parameters has also been observed. Scanning electron microscopy confirmed that the void and porosity seen in the unpeened gears were filled. The electron backscatter diffraction analysis confirms the grain refinement in LPwC region up to 100 μm depth. It was observed that multifold dislocation occurs within the grain, and dislocation generates sub-grain. The sub-grain formation substantially inhibits further nucleation and crack propagation owing to an increase in grain boundary density. Such improvement justifies the set objectives, and the outcome of this research will pave a foundation to improve the overall performance of the micro/meso parts using the LPwC process.

Original languageEnglish
Pages (from-to)764-773
Number of pages10
JournalJournal of Manufacturing Processes
Early online date15 Dec 2022
Publication statusPublished - 6 Jan 2023

Bibliographical note

© 2022 The Authors. Published by Elsevier Ltd on behalf of The Society of Manufacturing Engineers. This is an open access article under the CC
BY-NC-ND license (


This work was supported by the European Structural and Investment Fund and The Czech Ministry of Education, Youth and Sports (MSCA-IF IV FZU— CZ.02.2.69/0.0/0.0/20_079/0017754 ). The authors are also thankful for the support of ESIF , EU Operational Programme Research , Development and Education, and from the Center of Advanced Aerospace Technology ( CZ.02.1.01/0.0/0.0/16_019/0000826 ), Faculty of Mechanical Engineering, Czech Technical University in Prague .


  • Laser shock peening
  • Meso
  • Surface quality
  • Residual stresses
  • Microstructure

ASJC Scopus subject areas

  • Strategy and Management
  • Management Science and Operations Research
  • Industrial and Manufacturing Engineering


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