Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).
Please note that all times are shown in the time zone of the conference. The current conference time is: 7th Dec 2021, 09:56:31am CET
Session Chair: Daniel Holder, University of Stuttgart, Germany
Location:Room 1 ICM
10:00am - 10:15am
Effect of femtosecond laser shock peening on surface morphology and hardness of nickel titanium alloy
Hao Wang1, Evgeny L. Gurevich2, Andreas Ostendorf1
1Ruhr-Universität Bochum; 2Münster University of Applied Sciences
Nickel-titanium alloy (NiTi) has been widely used for the fabrication of microelectromechanical and body implants, so it is very important to enhance its surface mechanical property. Laser shock peening as a new and important surface treatment technique has been used to enhance the mechanical properties of different metal materials. Normally, the nanosecond laser with pulse-width between 5 ns and 20 ns is used to induce a high-pressure shock wave that can generate plastic deformation in the top layer of metals. In this paper, the surface morphology and hardness of NiTi alloy after femtosecond laser shock peening in the air are studied, which shows that the surface roughness and hardness increased after femtosecond laser treatment.
10:15am - 10:30am
Influence of multi-pass laser hardening on surface residual stress and distortion
Yang Lu1, Heiner Meyer2, Tim Radel1
1Bremer Institut für angewandte Strahltechnik GmbH; 2Leibniz-Institut für Werkstofforientierte Technologien
Laser hardening is used to harden the surface layer with minimal distortion and to induce residual compressive stress. Within the literature, the approach of increasing the hardness and hardening depth by multi-pass laser hardening based on accumulation effects is shown. Within this study, the effect of multi-pass laser hardening of normalized AISI 4140 on the surface residual stress and distortion is examined. The multi-pass laser hardening is carried out using a continuous wave laser with a rectangular beam shape using different process velocities and number of cycles without heat accumulation after each cycle. The results show that for a comparable hardening depth, there is less distortion at single pass hardening with low scanning speed compared to the multi-pass hardening with high scanning speed. These findings indicate that multi-pass laser hardening is therefore only preferable if technical limitations like the available laser power prevents the required hardening depth.
10:30am - 10:45am
Interaction between laser radiation and antifouling coating underwater
Stanislav Zimbelmann1, Benjamin Emde1, Jörg Hermsdorf1, Stefan Kaierle1, Tim Heusinger von Waldegge2, Dorothea Stübing2, Markus Baumann3
The biofouling on a ship´s hull has an enormous economic impact on its operation. Increasing biofouling leads to the introduction and spread of invasive species, a raised frictional drag in the water, an increased fuel consumption and thus an additional emission of greenhouse gases. In this context, the prevention or removal of biofouling becomes essential. Conventional, mechanical in-water-cleaning methods have several ecological and regulatory disadvantages. In the context of a laser-based underwater ship cleaning, that is currently under development, we investigated the interaction between laser radiation and a self-polishing copolymer (SPC) antifouling coating. Important process parameters were investigated to determine the laser power damage threshold of the SPC coating. These include the measurement of the reflection properties and the surface properties of the SPC coating.
10:45am - 11:00am
Laser cleaning as a productive surface post-treatment method for LPBF parts
Markus Hofele1,2, Johannes Neuer1, Malena Lindenberger-Ullrich1, Jochen Schanz1,2, David K. Harrison2, Anjali K. M. De Silva2, Harald Riegel2
1Aalen University, Germany; 2Glasgow Caledonian University, United Kingdom
Laser Powder Bed Fusion (LPBF) is the most common additive manufacturing technique for rapid prototyping and industrial manufacturing of complex individual metal parts. The LPBF process offers the opportunity to directly build solid metal parts with less geometric restrictions, low porosity and good mechanical properties. However, the surface of the parts exhibits a rough surface with massive powder contamination combined with a thick oxide layer on it. Laser cleaning provides the possibility of a contact-free and full-automatable surface treatment with high area rates.
This work deals with the investigation on laser cleaning of LPBF surfaces made of Aluminum AlSi10Mg. Laser cleaning with an nanosecond pulsed fiber laser by variation of the beam intensity, fluency and number of cleaning repetitions are investigated. Threshold beam intensities for the powder and oxide removal and base material ablation are determined. The ablation efficiency is analyzed by means of SEM, WLI and microscopic images.