Deforming TC6 titanium alloys at ultrahigh strain rates during multiple laser shock peening

The effect of shock waves and strain hardening of laser shock peening without protective coating (LSPwC) on alloy AA 6082-T651 was investigated. Analysis of residual stresses confirmed high compression in the near surface layer due to the ultrahigh plastic strains and strain rates induced by multiple laser shock waves. Corrosion tests in a chloride environment were carried out to determine resistance to localised attack, which was also verified on SEM/EDS. OCP transients confirmed an improved condition, that is, a more positive and stable potential after LSPwC treatment. Moreover, polarisation resistance of the LSPwC treated specimen was by a factor of 25 higher compared to the untreated specimen. Analysis of voltammograms confirmed an improved enhanced region of passivity and significantly smaller anodic current density of the LSPwC specimen compared to the untreated one. Through SEM, reduction of pitting attack at the LSPwC specimen surface was confirmed, despite its increased roughness.

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Residual Stress State and Fatigue Behaviour of Laser Shock Peened Titanium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.524-525.129 ◽

2006 ◽

Vol 524-525 ◽

pp. 129-134 ◽

Cited By ~ 3

Author(s):

I. Altenberger ◽

Yuji Sano ◽

M.A. Cherif ◽

Ivan Nikitin ◽

Berthold Scholtes

Keyword(s):

Residual Stress ◽

Titanium Alloys ◽

Cold Work ◽

Fatigue Behaviour ◽

Laser Shock Peening ◽

Fatigue Properties ◽

Stress Profile ◽

Laser Shock ◽

Near Surface ◽

Shock Peening

Laser shock peening is a very effective mechanical surface treatment to enhance the fatigue behaviour of highly stressed components. In this work the effect of different laser shock peening conditions on the residual stress depth profile and fatigue behaviour without any sacrificial coating layer is investigated for two high strength titanium alloys, Ti-6Al-4V and Timetal LCB. The results show that the optimization of peening conditions is crucial to obtain excellent fatigue properties. Especially, power density, spot size and coverage severely influence the residual stress profile of laser shock peened Ti-6Al-4V and Timetal LCB specimens. For both alloys, subsurface as well as surface compressive residual stress peaks can be obtained by varying the peening conditions. In general, Timetal LCB exhibits steeper stress gradients than Ti-6Al-4V for identical peening conditions. The main parameters affecting the fatigue life are near-surface cold work and compressive residual stresses.

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Regularity of Residual Stress Distribution in Titanium Alloys Induced by Laser Shock Peening with Different Energy Spatial Distributions

Laser & Optoelectronics Progress ◽

10.3788/lop55.061402 ◽

2018 ◽

Vol 55 (6) ◽

pp. 061402

Author(s):

李翔 Li Xiang ◽

何卫锋 He Weifeng ◽

聂祥樊 Nie Xiangfan ◽

杨竹芳 Yang Zhufang ◽

罗思海 Luo Sihai ◽

...

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Titanium Alloys ◽

Residual Stress Distribution ◽

Laser Shock Peening ◽

Spatial Distributions ◽

Laser Shock ◽

Shock Peening

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FE Modeling and Analysis of Patterning Micron Surface Structures by Laser Shock Peening

Volume 10: Mechanics of Solids and Structures, Parts A and B ◽

10.1115/imece2007-43842 ◽

2007 ◽

Author(s):

A. W. Warren ◽

Y. B. Guo

Keyword(s):

Mechanical Behavior ◽

High Strain ◽

Shock Pressure ◽

Surface Structures ◽

Laser Shock Peening ◽

Strain Rates ◽

Laser Shock ◽

High Strain Rates ◽

Direct Input ◽

Shock Peening

Laser shock peening (LSP) is a potential fabrication process to pattern micron surface structures. The purpose of this paper is to model 3D shock pressure and dynamic mechanical behavior at high strain rates during laser patterning process. The 3D shock pressure was modeled using a user defined subroutine. The mechanical behavior at high strain rates is predicted by the Bammann, Chiesa, and Johnson (BCJ) model. A 3D FEA model of microscale LSP was created using the developed loading and material subroutines. For comparison, a direct input of measured material properties was also used. The results show that decreasing pulse time shifts the maximum transient stress from the surface to the subsurface. The rapid loading causes increased magnitudes of compressive stress throughout the depth. The BCJ model predicts higher stresses than the direct input method.

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A critical appraisal of laser peening and its impact on hydrogen embrittlement of titanium alloys

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405419838956 ◽

2019 ◽

Vol 233 (13) ◽

pp. 2371-2398 ◽

Cited By ~ 2

Author(s):

G Ranjith Kumar ◽

G Rajyalakshmi ◽

S Swaroop

Keyword(s):

Hydrogen Embrittlement ◽

Titanium Alloys ◽

Corrosion Behaviour ◽

Weight Ratio ◽

Theoretical Models ◽

Laser Shock Peening ◽

Laser Peening ◽

Laser Shock ◽

Hydrogen Degradation ◽

Shock Peening

Many efforts have been made to understand the effects of hydrogen on titanium alloys, resulting in an abundance of theoretical models and papers. Titanium alloys are crucial advanced materials that provide an excellent combination of a high strength-to-weight ratio and good corrosion behaviour even though they are reasonable to corrosion attack. Titanium alloys are susceptible to hydrogen embrittlement when comes into contact with hydrogen, and galvanic pair with an active metal current, or the pH is greater than 12 or less than 3 or an impressed current. In view of the fact that hydrogen behaves differently with α and β phases, hydrogen degradation may vary markedly in titanium alloys. Hydrogen diminishes the corrosion and erosion resistance and fatigue life of in-service titanium components. A laser peening or laser shock peening is a novel technique for making the metal surfaces and sub-layers densify. It evokes that laser shock peening adoption results in yielding and plastic deformation, thereby creating high compressive residual stresses extending below the surface of the material which is desirable for hydrogen embrittlement resistance and reduction of crack initiation and growth of the component. This article is a review of information relating hydrogen embrittlement of titanium alloys and surface modification technique which influence the strength potential of titanium alloys.

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