Warm Laser Shock Peening Driven Nanostructures and Their Effects on Fatigue Performance in Aluminum Alloy 6160

Ye, Chang; Liao, Yiliang; Cheng, Gary J.

doi:10.1002/adem.200900290

Cited by 87 publications

(37 citation statements)

References 16 publications

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“…This phenomenon is also observed in other reported literatures [11,12,17]. On the other hand, replacing H2O by H2O2 could break this major limitation and enhance the hardness up to around 132 VHN, which is close to the saturated hardness value of AA6061 caused by the strain hardening [18]. Meanwhile, H2O2 brings a relatively larger surface deformation depth as well ( Fig.…”

supporting

confidence: 71%

Enhanced Laser Shock by an Active Liquid Confinement—Hydrogen Peroxide

Liao

Yang

Cheng

2012

Journal of Manufacturing Science and Engineering

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This letter investigates a unique process to generate enhanced laser shock by applying an active liquid confinement-hydrogen peroxide (H2O2). The mechanism of fast chemical etching-assisted laser ablation is proposed. As a result, comparing with utilizing water as confinement, the efficiency of laser shock peening (LSP) of aluminum alloy 6061 with an active liquid confinement is improved by 150%, and the ablation rate of pulse laser ablation (PLA) of zinc is enhanced by 300%. This method breaks the major limitation of underwater pulsed laser processing caused by the breakdown plasma, with additional mechanisms to generate higher ablation rate and shock pressure under the same laser intensities.The laser shock induced by pulse laser ablation under a confinement has been widely investigated because of its great potential for industrial applications, such as LSP [1-6], laser dynamic forming [7,8], and laser-assisted micromachining [9,10]. The capability, efficiency, and application range of these laser-based techniques are strongly governed by the intensity of laser shock. Thus, enhancing the laser shock draws a great attention in this research field. The laser shock is ruled over by not only the laser power condition but also the confining media. Currently, the selection of confining media brings a major limitation to enhance the laser shock. For example, the solid confinements like glass are inconvenient for processing 3D surfaces, and they are also too brittle to stand the high power laser pulse. On the other hand, even if the liquid confinements like water are relatively more fiexible and practical, and have been widely used in industrial applications, they still suffer from the major drawback: When the laser intensity is above a threshold, the breakdown of liquid confinements screens the incident laser power and results in a saturation of laser shock and peak pressure [1,4,11,12]. Thus, it is worthwhile exploring other approaches to enhance the laser shock.In this letter, we study a unique process to enhance the laser shock by applying active liquid confinements like H2O2. The concept originates from that the laser shock is mostly dependent on the high density of laser-induced plasma, which is determined by the ablation rate of target materials through laser-material interactions [2,9,13,14]. Thus, we could effectively enhance the laser shock by using active liquid confinements because of the more effective ablation caused by the fast chemical etching reaction taking place simultaneously during laser ablation process. This idea is demonstrated by experimental results that the surface hardness and plastic deformation depth of aluminum alloy 6061 (AA6061) after LSP are effectively increased by using H2O2 as the confinement instead of H2O. LSP efficiency is improved by 150% with the application of H2O2. Our proposed mechanism suggests that the enhanced laser shock by H2O2 is majorly due to the higher ablation rate caused by the mutual promotion between the laser ablation and chemical etching. In addition, this mec...

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supporting

confidence: 71%

Enhanced Laser Shock by an Active Liquid Confinement—Hydrogen Peroxide

Liao

Yang

Cheng

2012

Journal of Manufacturing Science and Engineering

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“…Our previous research verified WLP as an effective process to maintain more stable compressive residual stress on the surface of a treated Ti-6Al-4V alloy, resulting in better fatigue performance [16]. From the micro aspect, Ye's group observed some nanoscale precipitates in the WLP-treated AA 6061-T6 [17], and it is preliminary believed that these ultra-high-density nano-precipitates greatly improve the dislocation accumulation capacity and effectively increase the ductility of metals [18]. However, more convincing evidence and scientific data are required to validate the effectiveness of the WLP process on the surface properties.…”

Section: Introductionmentioning

confidence: 80%

Residual Stress Distribution and Microstructure Evolution of AA 6061-T6 Treated by Warm Laser Peening

Huang

Wang

Sheng

et al. 2016

Metals

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Abstract:The aim of this paper is to study the effects of laser peening (LP) on the residual stress distribution and microstructure evolution of AA 6061-T6 under different temperatures. A laser peening experiment was conducted on the square-shape samples by using single spot and 50% overlap shock. Three-dimensional surface morphologies of treated samples were observed. The influence of peening temperature on the distribution of compressive residual stress was analyzed. An optical microscope (OM) and a transmission electron microscope (TEM) were employed to observe the microstructure evolution of the samples before and after LP. The results indicate that, as the peening temperature increases, the micro-hardness increases first and then decreases. The LP process induces high-amplitude compressive residual stress on the surface at different temperatures even if the compressive residual stress slightly reduces with increases in temperature. The maximum compressive residual stress affected layer depth is about 0.67 mm, appearing at a temperature of 160 • C. The OM test revealed that the grain size was significantly decreased after warm laser peening (WLP) and that the average value of grain size was reduced by 50%. The TEM test shows that more dislocation tangles were produced in AA 6061-T6 after WLP; compared to the LP process, the precipitate-dislocation interaction can benefit both strength and ductility for AA 6061-T6, thus enhancing the mechanical properties of the material.

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“…It now has become commercially available and is proposed as a competitive alternative surface enhancement and thick plate form ing process to improve fatigue resistance of metallic components [1][2][3]. A large number of trial-and-error experiments are typically required on high-value parts before practical applications can be achieved for LSP, which makes the processing cost very high.…”

Section: Introductionmentioning

confidence: 99%

Predictive Modeling and Uncertainty Quantification of Laser Shock Processing by Bayesian Gaussian Processes With Multiple Outputs

et al. 2014

Journal of Manufacturing Science and Engineering

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Accurate numerical modeling of laser shock processing, a typical complex physical pro cess, is very difficult because several input parameters in the model are uncertain in a range. And numerical simulation of this high dynamic process is very computational expensive. The Bayesian Gaussian process method dealing with multivariate output is introduced to overcome these difficulties by constructing a predictive model. Experiments are performed to collect the physical data of shock indentation profiles by varying laser power densities and spot sizes. A two-dimensional finite element model combined with an analytical shock pressure model is constructed to obtain the data from numerical simula tion. By combining observations from experiments and numerical simulation of laser shock process, Bayesian inference for the Gaussian model is completed by sampling from the posterior distribution using Morkov chain Monte Carlo. Sensitivities o f input parame ters are analyzed by the hyperparameters of Gaussian process model to understand their relative importance. The calibration of uncertain parameters is provided with posterior distributions to obtain concentration of values. The constructed predictive model can be computed efficiently to provide an accurate prediction with uncertainty quantification for indentation profile by comparing with experimental data.

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Warm Laser Shock Peening Driven Nanostructures and Their Effects on Fatigue Performance in Aluminum Alloy 6160

Cited by 87 publications

References 16 publications

Enhanced Laser Shock by an Active Liquid Confinement—Hydrogen Peroxide

Enhanced Laser Shock by an Active Liquid Confinement—Hydrogen Peroxide

Residual Stress Distribution and Microstructure Evolution of AA 6061-T6 Treated by Warm Laser Peening

Predictive Modeling and Uncertainty Quantification of Laser Shock Processing by Bayesian Gaussian Processes With Multiple Outputs

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