Fatique properties of laser welds made with beam oscillations

0584173 - ÚPT 2024 DE eng A - Abstract
Šebestová, Hana - Mrňa, Libor - Jambor, Michal
Fatique properties of laser welds made with beam oscillations.
Laser Symposium & ISAM 2023. Dresden: Fraunhofer Institute for Material and Beam Technology IWS, 2023. s. 52. ISBN N.
[Laser Symposium /12./ and International Symposium Additive Manufacturing (ISAM) /5./ 2023. 29.11.2023-01.12.2023, online]
Grant - others:AV ČR(CZ) StrategieAV21/17
Program: StrategieAV
Institutional support: RVO:68081731 ; RVO:68081723
Keywords : laser welding * beam oscillation * power density * fatigue * notch * microstructure
OECD category: Mechanical engineering

Three different oscillation modes of the same oscillation diameter and frequency were proposed and experimentally investigated to modify laser weld geometry and reduce the root notches. The oscillation modes with a lower fluctuation in energy per unit trajectory length (circle, cardioid) led to the elimination of weld root defects. In contrast, the line oscillation promoted the formation of a lean root of large concavity. Although the fatigue properties are generally notch-sensitive, the line oscillation welds achieved better fatigue properties at the region of high lifetimes than low-notch welds of other modes. It is attributed to the simpler sinusoidal beam trajectory compared to the other two modes at which the beam repeatedly passes the melt pool, thus increasing the number of phase transformations inducing internal stresses. From the fatigue point of view, even a significant defect can be compensated by more beneficial microstructure and less residual stresses. All the aspects must be considered. Thus, predicting a welded structure's fatigue behavior is a very complex issue, especially when the beam oscillation is involved.
Permanent Link: https://hdl.handle.net/11104/0352158