Femtosecond laser peening of 2024 aluminum alloy without a sacrificial overlay under atmospheric conditions

Sano, Tomokazu; Eimura, Takayuki; Kashiwabara, Ryota; Matsuda, Tomoki; Isshiki, Yutaro; Hirose, Akio; Tsutsumi, Sadami; Arakawa, Kazuto; Hashimoto, Tadafumi; Kobayashi, Masaki; Sano, Yuji

doi:10.2351/1.4967013

Cited by 67 publications

(20 citation statements)

References 37 publications

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“…The tensile residual stresses in the WM, below the weld toe, and in the HAZ were observed to a depth of ~300 µm from the weld center in the as-welded specimen. These tensile residual stresses inside the material between the surface and a depth of ~100 µm changed to compressive stresses after DryLP, which is comparable to the thickness of the compressive layer in the DryLPed BM [9].…”

Section: Residual Stressmentioning

confidence: 68%

“…However, areas of WM with reduced strength exist, and avoiding generation of blowholes in the laser-welded joints is difficult. Although the thickness with the compressive residual stress induced by DryLP process is almost one-tenth of conventional LP methods [9,10], this method was shown to be effective for FSW-processed 7075-T73 aluminum alloy, where the stir zone, thermo-mechanically affected zone, and HAZ were softened, but no welding defects occurred, confirming that the fatigue performance was better than that of the BM at lower stress amplitude after DryLP treatment. However, the effectiveness of DryLP on welded precipitation-strengthened aluminum alloy containing welding defects has never been investigated.…”

mentioning

confidence: 86%

“…Unlike other A single-mode fiber laser (IPG Photonics, YLS-2000-SM, Japan, wavelength: 1070 nm, CW) was used for full-penetration bead-on-plate welding of the aluminum alloy, as shown in Figure 1a. The fiber Metals 2019, 9,1192 3 of 13 diameter was 14 µm and we used a laser power of 2.0 kW. The laser was focused on the alloy surface with a spot size of 54 µm.…”

Section: Introductionmentioning

confidence: 99%

“…As shown in Figure 1b,c, femtosecond laser pulses with a wavelength of 800 nm, pulse duration of 130 fs, and pulse energy of 0.6 mJ (Spectra-Physics, Spitfire, Japan) were focused using a plano-convex lens with focal length of 70 mm onto the specimen. The laser pulses were overlapped, with a coverage of 692%, which was shown to be the most effective condition for DryLP of 2024-T3 aluminum alloy [9]. A detailed description of the DryLP process was provided in the previous study.…”

Section: Introductionmentioning

confidence: 99%

“…A LP method that does not require such a coating has been developed using an irradiation source formed by overlapping low-energy pulses [7,8]. Furthermore, a dry LP (DryLP) technique has been developed that does not require a sacrificial overlay and is performed under ambient conditions, where the material is directly irradiated using femtosecond laser pulses [9][10][11]. Although femtosecond laser pulses have a small pulse energy, the electric field is so strong that the material is explosively ablated without requiring the opaque overlay or the plasma confinement medium [12,13].…”

mentioning

confidence: 99%

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

Sano

Eimura

Hirose

et al. 2019

Metals

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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.

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Section: Residual Stressmentioning

confidence: 68%

mentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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

Sano

Eimura

Hirose

et al. 2019

Metals

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Recent Developments and Novel Applications of Laser Shock Peening: A Review

2021

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Wear, corrosion, and fatigue are responsible for more than 80% of the failures of metallic materials. As most failures caused by wear, corrosion, and fatigue initiate from the material surface, surface integrity has a crucial impact on the overall performance of the materials. Surface integrity characteristics, including hardness, microstructure, morphology, roughness, and residual stress status, can significantly affect the wear and corrosion behavior. By improving hardness and introducing beneficial compressive residual stresses in the near-surface region, laser shock peening (LSP) can significantly improve the fatigue performance of metallic materials. In the LSP process, light from a high-energy pulsed laser penetrates through the transparent confinement media and irradiates the ablative coating, quickly heating the affected area to a high temperature and generating high-pressure plasma. The expansion of the plasma causes a shockwave that can plastically deform the target metals, resulting in work hardening and compressive residual stresses. Compared with shot peening (SP), LSP has the following advantages. 1) LSP can produce deeper layers of compressive residual stresses; 2) the process parameters in LSP can be precisely controlled; 3) the surface integrity of the parts after LSP is improved without the need for postprocessing; 4) LSP can be used to treat components with complex geometry; and 5) LSP has a high processing efficiency and makes for a clean working environment. Because LSP represents a new generation of surface strengthening technology that can replace SP, it has gained wide attention. Askar'yan and Moroz measured the pressures exerted by a high-intensity laser beam on the surface of a metal target [1] and found that this pressure is sufficient for steering space vehicles. However, the experiments were conducted under vacuum conditions to prevent dielectric breakdown, and such conditions are not practical for use in industry. [2] Anderholm at Sandia Laboratories irradiated an aluminum film covered in quartz with a laser beam and found that the presence of a transparent confinement layer can significantly increase the shock pressure. [3] Although this experiment was also conducted in vacuum, it proved that with the presence of a transparent confinement layer, a laser power density that does not cause dielectric breakdown in air can also generate a sufficiently large shock pressure. This observation is of great significance for the later industrial applications that involve laser-generated shockwaves.Fairand et al. at Battelle Memorial Institute changed the microstructure of 7075 aluminum alloy through short-pulse, laser-induced shockwaves with a high power density, and they found that after processing, the stress corrosion cracking (SCC) resistance and fatigue performance of the alloy improved. [4] This is a key event in the development of LSP; after this study, the National Science Foundation of the United States began to support the investigation of LSP. Clauer et al. [5] changed the intensity ...

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Engineering Stress in Thin Films: An Innovative Pathway Toward 3D Micro and Nanosystems

Truong

Nguyen

Zhao

et al. 2021

Small

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Transformation of conventional 2D platforms into unusual 3D configurations provides exciting opportunities for sensors, electronics, optical devices, and biological systems. Engineering material properties or controlling and modulating stresses in thin films to pop‐up 3D structures out of standard planar surfaces has been a highly active research topic over the last decade. Implementation of 3D micro and nanoarchitectures enables unprecedented functionalities including multiplexed, monolithic mechanical sensors, vertical integration of electronics components, and recording of neuron activities in 3D organoids. This paper provides an overview on stress engineering approaches to developing 3D functional microsystems. The paper systematically presents the origin of stresses generated in thin films and methods to transform a 2D design into an out‐of‐plane configuration. Different types of 3D micro and nanostructures, along with their applications in several areas are discussed. The paper concludes with current technical challenges and potential approaches and applications of this fast‐growing research direction.

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Femtosecond laser peening of 2024 aluminum alloy without a sacrificial overlay under atmospheric conditions

Cited by 67 publications

References 37 publications

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

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

Recent Developments and Novel Applications of Laser Shock Peening: A Review

Engineering Stress in Thin Films: An Innovative Pathway Toward 3D Micro and Nanosystems

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