Effective femtosecond laser shock peening on a Mg–3Gd alloy at low pulse energy 430 µJ of 1 kHz

Lu, Chenghao; Ge, Licheng; Zhu, Bing; Li, Yangxin; Chen, Xianfeng; Zeng, Xiaoqin; Chen, Yuping

doi:10.1016/j.jma.2019.05.005

Cited by 26 publications

(5 citation statements)

References 16 publications

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“…[44] These dominate the changes in the surface and in-depth residual stress during NLSP. As shown in Figure S5, Supporting Information, the compressive residual stresses induced by FLSC [46,47] are tuned to tensile states on the colorized surfaces after NLSP near peened surfaces. The limitation of the plasma generation induced by weak light coupling and the negative effect of tensile stress induced by thermal ablation [48,49] lead to shallow affected depths for light yellow samples.…”

Section: Peak Pressure Generation and Residual Stress Distributionmentioning

confidence: 99%

Improvement of Laser Shock Peening Depth Through Regulation of Surface Optical Absorption

Yan

Zhu

et al. 2021

Adv Materials Inter

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Higher depths at the millimeter scale (1-2 mm), along with greater magnitudes, have been reported after the NLSP of Ti6Al4V titanium alloy, [2,10] 2024, [11] 6061, [12] and 7075 [13] aluminum alloys. Elaborated laser systems with large power densities are currently required to increase the peak pressure to enable a high input of energy (slightly over 10 GW cm -2 ) during the interaction between the incident laser and metals. [14] The critical power density threshold for the confinement layer breakdown is validated to limit the possible peak pressure. [15][16][17] Changing the wavelength of the incident laser from 1064 to 532 nm decreases the breakdown threshold of the confining water layers from 10 to 6 GW cm -2 , and the maximum peak pressure from ≈5.5 to 4.5 GPa. [18,19] Compressive residual stresses can also be generated deep below the peened surface by multiple or overlapping laser pulses. [20,21] The reduced attenuation of the shock wave indicates an increased depth for the plastic-deformed layer during subsequent peening, while the affected depths usually reach saturated border values within three to five impacts. [22,23] Additionally, femtosecond laser shock peening is applied to induce a shallower affected depth and a limited compressive layer owing to the high instantaneous power density. [24] It is necessary to increase the surface optical absorption and associated energy conversion at higher affected depths in NLSP. The surface optical absorption property determines the thermal energy fraction, [25,26] with a value of ≈0.2 utilized in investigations. [27,28] In this case, optical absorption is defined by the surface morphology of the metal rather than its intrinsic absorptance. [29] Various absorption mechanisms with different optical behaviors are found in the structures induced using lithographic and chemical techniques. [30,31] These essentially originate from selective absorption responses such as the surface plasmon resonance, magnetic-polariton, geometric optical response, and metamaterial resonances. [29,[32][33][34] A nanoscale structure and laser-induced periodic surface structure can enhance the absorption of laser energy by the reconstruction of surface electromagnetic distributions. [35] The absorption of light is enhanced on structured surfaces by multiple reflections based on the angular dependence of Fresnel absorption. [35] The absorption spectrum of femtosecond laser treated surfaces increased sharply over a wide range of wavelengths of incident Laser shock peening is conducted to enhance the mechanical properties of metals. Efficient optical absorption of metal surface is desirable to increase the laser shock peening depth. In this work, a method is proposed to regulate the absorption behavior by surface colorizing to increase the affected depth and magnitude of nanosecond laser shock peening (NLSP). Colorized samples are fabricated with high absorption of 400-1500 nm, which is 89% higher than that of un-colorized samples. This regulated optical response is attributed to the multi-ref...

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Section: Peak Pressure Generation and Residual Stress Distributionmentioning

confidence: 99%

Improvement of Laser Shock Peening Depth Through Regulation of Surface Optical Absorption

Yan

Zhu

et al. 2021

Adv Materials Inter

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“…In contrast, femtosecond laser shock peening (FLSP) can be conducted directly under air conditions, which provides different engineering potentials [22][23][24]. In FLSP processing, milli-Joule-scale energy input (even micro-Joule-scale energy input [25,26]) is adopted, which is three orders of magnitude lower than that used in NLSP [20,22,23]. Due to the ultra-short duration characteristics, FLSP induces high shock wave pressure of several hundred GPa in the air with milli-Joule-scale energy [25,26], whereas 1-10 GPa pressure can be induced in NLSP with Joule-scale energy [13,14,20].…”

Section: Introductionmentioning

confidence: 99%

“…In FLSP processing, milli-Joule-scale energy input (even micro-Joule-scale energy input [25,26]) is adopted, which is three orders of magnitude lower than that used in NLSP [20,22,23]. Due to the ultra-short duration characteristics, FLSP induces high shock wave pressure of several hundred GPa in the air with milli-Joule-scale energy [25,26], whereas 1-10 GPa pressure can be induced in NLSP with Joule-scale energy [13,14,20]. The introduction of water layers weakens the peening effects as strong ionization of confining medium shields the majority absorption of incident laser energy [20].…”

Section: Introductionmentioning

confidence: 99%

“…During FLSP, dense dislocation, refined grains, and compressive residual stresses are induced near the peened surface [27]. Thus, similar improvement of surface mechanical properties can be achieved with lower energy input, compared with NLSP, such as surface hardness [26,28], anti-corrosion properties [9,23], anti-fatigue properties [22,29]. Moreover, surface textures and ripples are formed on those peened surfaces to obtain the multifunctional surfaces, which is a unique characteristic of FLSP [25].…”

Section: Introductionmentioning

confidence: 99%

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Laser Shock Peening of Ti6Al4V Alloy with Combined Nanosecond and Femtosecond Laser Pulses

Sun¹,

Bai

et al. 2021

Metals

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Laser shock peening (LSP) with nanosecond or femtosecond laser pulses is applied to improve the mechanical properties of metallic materials. Thus, it is necessary to compare the effects of different processing methods on microstructure changes and property improvement. In this study, nanosecond LSP (NLSP), femtosecond LSP (FLSP), and LSP with combined nanosecond and femtosecond laser pulses (F-NLSP) are conducted on Ti6Al4V alloys to compare the surface morphologies, in-depth microstructures, and nanohardness changes. In FLSP, the peened surface is smooth, and the affected depth is limited near the peened surface. NLSPed and F-NLSPed samples present rough surfaces due to the severe ablation process. Small equiaxed grains with no preferred grain orientation are denser in F-NLSPed samples than that in NLSPed samples. Compared with NLSPed samples, the affected depth and amplitude of in-depth nanohardness are larger in F-NLSPed samples. This is attributed to the increased laser absorption of incident laser on the treated surface by femtosecond laser pulses. The results in this study show the effects of different LSP methods and provide chances in engineering potentials for material property improvements.

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“…Compared with ns-LSP, fs-LSP is found to introduce higher surface hardness at lower energy input 36 and interact differently with the confinement medium and protective coating than ns-laser. 35 For instance, Lu et al 37 found that the surface hardness of Mg−3Gd alloy is improved by 70% through fs-LSP with 430 μJ pulse energy, as compared to 45.1% using ns-LSP with 9 J pulse energy due to less thermally facilitated subsurface structure relaxation. Apart from the effective strength improvement, fs-LSP is also beneficial to corrosion resistance enhancement.…”

Section: Introductionmentioning

confidence: 99%

Enabling High-Performance Surfaces of Biodegradable Magnesium Alloys via Femtosecond Laser Shock Peening with Ultralow Pulse Energy

Wang

Hung

Howe

et al. 2021

ACS Appl. Bio Mater.

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The fast degradation rate and poor wear resistance of magnesium (Mg) alloys in physiological environments have limited their potential usage as next-generation biodegradable orthopedic implant materials. In this work, femtosecond laser shock peening (fs-LSP) was successfully applied to simultaneously improve the surface mechanical, corrosion, and tribocorrosion properties of WE43 Mg alloys in blood bank buffered saline solution at body temperature. Specifically, the treated surfaces of WE43 Mg alloys via fs-LSP with ultralow pulse energy were investigated under different power densities, confining mediums, and absorbent materials. It was found that the combination of a black tape and a quartz layer gave the optimum peening effect under a power density of 28 GW/cm 2 , which simultaneously strengthened the surface and reduced the corrosion kinetics. In addition, a rapid self-repassivation was observed in fs-LSP-treated WE43 surfaces during tribocorrosion, promising sustained corrosion resistance under mechanical loading, critical to the reliability of load-bearing implants. Finally, the subsurface microstructural evolution and residual stress development in WE43 after fs-LSP were discussed based on the results from transmission electron microscopy analysis and finite element simulations.

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Effective femtosecond laser shock peening on a Mg–3Gd alloy at low pulse energy 430 µJ of 1 kHz

Cited by 26 publications

References 16 publications

Improvement of Laser Shock Peening Depth Through Regulation of Surface Optical Absorption

Improvement of Laser Shock Peening Depth Through Regulation of Surface Optical Absorption

Laser Shock Peening of Ti6Al4V Alloy with Combined Nanosecond and Femtosecond Laser Pulses

Enabling High-Performance Surfaces of Biodegradable Magnesium Alloys via Femtosecond Laser Shock Peening with Ultralow Pulse Energy

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Effective femtosecond laser shock peening on a Mg–3Gd alloy at low pulse energy 430 µJ of 1 kHz

Cited by 26 publications

References 16 publications

Improvement of Laser Shock Peening Depth Through Regulation of Surface Optical Absorption

Improvement of Laser Shock Peening Depth Through Regulation of Surface Optical Absorption

Laser Shock Peening of Ti6Al4V Alloy with Combined Nanosecond and Femtosecond Laser Pulses

Enabling High-Performance Surfaces of Biodegradable Magnesium Alloys via Femtosecond Laser Shock Peening with Ultralow Pulse Energy

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Effective femtosecond laser shock peening on a Mg–3Gd alloy at low pulse energy 430 µJ of 1 kHz