Improving Fatigue Performance of Laser-Welded 2024-T3 Aluminum Alloy Using Dry Laser Peening

Abstract

The purpose of the present study was to verify the effectiveness of dry laser peening (DryLP), which is the peening technique without a sacrificial overlay under atmospheric conditions using femtosecond laser pulses on the mechanical properties such as hardness, residual stress, and fatigue performance of laser-welded 2024 aluminum alloy containing welding defects such as undercuts and blowholes. After DryLP treatment of the laser-welded 2024 aluminum alloy, the softened weld metal recovered to the original hardness of base metal, while residual tensile stress in the weld metal and heat-affected zone changed to compressive stresses. As a result, DryLP treatment improved the fatigue performances of welded specimens with and without the weld reinforcement almost equally. The fatigue life almost doubled at a stress amplitude of 180 MPa and increased by a factor of more than 50 at 120 MPa. DryLP was found to be more effective for improving the fatigue performance of laser-welded aluminum specimens with welding defects at lower stress amplitudes, as stress concentration at the defects did not significantly influence the fatigue performance.

Laser Shock Processing and Related Phenomena

“…In the second section (comprising nine full research papers), we aimed to compile as representative as possible coverage of the different key aspects leading the present-day research in LSP technology and related disciplines. The result has been a collection of articles ranging from the study of fundamental physics aspects (mostly laser-plasma interaction diagnosis and plasma pressure development, respectively represented by the articles of Colón et al [3] and Sadeh et al [4]); passing through the application of numerical modelling to the predictive assessment of the results of the application of LSP to the most relevant present-day materials (represented by the articles of Langer et al [5] and Angulo et al [6]); continuing on to the theoretical and experimental analysis of the parametric space of LSP in view of realistic applications (represented by the articles of Kallien et al [7], Troiani and Zavatta [8], and Petan et al [9]); and, finally, arriving at two of the most advanced developments at present day in the industrial application of LSP (i.e., the articles of Le Bras et al [10] and T. Sano et al [11]). In short, a collection of first-rank articles covering fundamental processes, numerical modelling, microstructural and material-related issues, materials and standard specimens testing, parametric applications design, advanced LSP applications, and implementation issues has been obtained.…”

Development of Laser Cavitation Peening Using a Normal-Oscillation Nd:YAG Laser

“…In both the first and the second cases, a confining medium such as water is required. In the third case, a confining medium is not required as a femtosecond laser is used [24]; this method is called dry laser peening [25,26].…”

Influence of Pulse Duration on Mechanical Properties and Dislocation Density of Dry Laser Peened Aluminum Alloy using Ultrashort pulsed Laser-driven Shock Wave

“…To prevent the melting, a protective coating, such as a metal film or paint, is applied to the material surface. 10 Meanwhile, dry laser peening (DLP) uses femtosecond laser pulses, [11][12][13] which eliminates the need for any plasma confinement medium or protective coating in the air. At a high intensity of femtosecond laser irradiation, thin layers of the surface are removed explosively with more intense laser ablation as compared with that of nanosecond laser irradiation.…”