Surface Conditions after LASER Shock Peening of Steel and Aluminum Alloys Using Ultrafast Laser Pulses

Jan Schubnell; Eva-Regine Carl; Ardeshir Sarmast; Manuel Hinterstein; Johannes Preußner; Marco Seifert; Christoph Kaufmann; Peter Rußbüldt; Jan Schulte

doi:10.3390/ma16206769

Surface Conditions after LASER Shock Peening of Steel and Aluminum Alloys Using Ultrafast Laser Pulses

Materials (Basel). 2023 Oct 19;16(20):6769. doi: 10.3390/ma16206769.

Authors

Jan Schubnell¹, Eva-Regine Carl¹, Ardeshir Sarmast¹, Manuel Hinterstein¹, Johannes Preußner¹, Marco Seifert², Christoph Kaufmann², Peter Rußbüldt³, Jan Schulte³

Affiliations

¹ Fraunhofer Institute for Mechancis of Materials IWM, Woehlerstr. 11, 79109 Freiburg, Germany.
² Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 18, 01277 Dresden, Germany.
³ Fraunhofer Institute for Laser Technology, Steinbachstr. 15, 52074 Aachen, Germany.

Abstract

Laser shock peening (LSP) is a mechanical surface treatment process to modify near-surface material properties. Compared to conventional shot peening (SP) the process parameters can be finely adjusted with greater precision and a higher penetration depth of compressive residual stresses could be reached. However, high process times of LSP leads to high production costs. In this study, ultrafast LSP (U-LSP) with an ultrafast laser source (pulse time in the picosecond range) was applied on specimens made of X5CrNiCu15-5 and AlZnMgCu1.5. The surface characteristics (surface roughness) and surface-near properties (microstructure, residual stresses, and phase composition) were compared to the as-delivered condition, to conventional laser shock peening (C-LSP), and to SP, whereas metallographic analyses and X-ray and synchrotron radiation techniques were used. The process time was significantly lower via U-LSP compared to C-LSP. For X5CrNiCu15-5, no significant compressive residual stresses were induced via U-LSP. However, for AlZnMgCu1.5, similar compressive residual stresses were reached via C-LSP and U-LSP; however, with a lower penetration depth. A change in the phase portions in the surface layer of X5CrNiCu15-5 after C-LSP compared to SP were determined.

Keywords: aluminum alloys; laser shock peening; microstructure; residual stresses; shot peening; steel; surface roughness.

Grants and funding

This research was funded by the Fraunhofer Society for the Advancement of Applied Research within the Research Cluster of Advanced Photon Source (CAPS) and the Fraunhofer Internal Programs under grant No. Attract 40-04857. We acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Parts of this research were carried out at PETRA III and we would like to thank Alexander Schoekel and Martin Etter for assistance in using the P02.1 beamline. Beamtime was allocated for proposal I-20220124.