Special Issue "Laser Shock Processing on Metal"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 October 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Patrice Peyre

Directeur de Recherche au CNRS, Groupe Laser, PIMM - UMR 8006 CNRS - Arts et Métiers ParisTech, 151 Bd de l'Hôpital, 75013 Paris, France
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Special Issue Information

Dear Colleagues,

Since its invention in the late 1960’s, and the pioneering work on metal strengthening in USA during the late 1970's, Laser Shock Processing has become a reliable surface treatment for improving the mechanical or corrosion resistance of metallic materials. This Special Issue on LSP aims to provide a rather exhaustive and up-to-date state of the art on LSP. Based upon recent work, the Special Issue covers the following fields: the physics of the process and shock loading conditions, the surface modifications induced by LSP, the modeling of LSP, the fatigue and corrosion properties of peened surfaces, the industrial applications of LSP, and novel applications for laser-induced shock waves.

Prof. Dr. Patrice Peyre
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • laser
  • shock-waves
  • peening
  • residual stresses
  • fatigue
  • corrosion

Published Papers (8 papers)

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Editorial

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Open AccessEditorial Laser Shock Processing on Metal
Metals 2017, 7(10), 409; doi:10.3390/met7100409
Received: 28 September 2017 / Revised: 28 September 2017 / Accepted: 28 September 2017 / Published: 1 October 2017
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(This article belongs to the Special Issue Laser Shock Processing on Metal)

Research

Jump to: Editorial

Open AccessFeature PaperArticle Laser-Driven Ramp Compression to Investigate and Model Dynamic Response of Iron at High Strain Rates
Metals 2016, 6(12), 320; doi:10.3390/met6120320
Received: 14 October 2016 / Revised: 2 December 2016 / Accepted: 8 December 2016 / Published: 18 December 2016
Cited by 2 | PDF Full-text (1503 KB) | HTML Full-text | XML Full-text
Abstract
Efficient laser shock processing of materials requires a good characterization of their dynamic response to pulsed compression, and predictive numerical models to simulate the thermomechanical processes governing this response. Due to the extremely high strain rates involved, the kinetics of these processes should
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Efficient laser shock processing of materials requires a good characterization of their dynamic response to pulsed compression, and predictive numerical models to simulate the thermomechanical processes governing this response. Due to the extremely high strain rates involved, the kinetics of these processes should be accounted for. In this paper, we present an experimental investigation of the dynamic behavior of iron under laser driven ramp loading, then we compare the results to the predictions of a constitutive model including viscoplasticity and a thermodynamically consistent description of the bcc to hcp phase transformation expected near 13 GPa. Both processes are shown to affect wave propagation and pressure decay, and the influence of the kinetics of the phase transformation on the velocity records is discussed in details. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
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Open AccessFeature PaperArticle Nanocrystallization in the Duplex Ti-6Al-4V Alloy Processed by Multiple Laser Shock Peening
Metals 2016, 6(12), 297; doi:10.3390/met6120297
Received: 14 October 2016 / Revised: 18 November 2016 / Accepted: 22 November 2016 / Published: 24 November 2016
Cited by 1 | PDF Full-text (2905 KB) | HTML Full-text | XML Full-text
Abstract
Laser shock peening of titanium alloys has been widely applied in the aerospace industry. However, little is known of the nanocrystalline formation characteristics and mechanisms. In this investigation, a nanocrystalline layer was formed in the duplex Ti-6Al-4V titanium alloy surface region by means
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Laser shock peening of titanium alloys has been widely applied in the aerospace industry. However, little is known of the nanocrystalline formation characteristics and mechanisms. In this investigation, a nanocrystalline layer was formed in the duplex Ti-6Al-4V titanium alloy surface region by means of multiple pulsed laser shock peening (LSP). The phase transition and residual stress characteristics of LSP samples were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was used to characterize the microstructure and morphologies. As the number of laser pulses increased for each location, higher grain refinement was observed. Micro-hardness testing showed that hardness increased with the number of pulses delivered to each location due to the formation of nanocrystalline layers and high dislocation density in the samples, and a gradient variation of the micro-hardness was obtained. In addition, mechanical twins and different dislocation configurations were formed in the α phase region while only dense dislocation tangles were observed in the β phase region after multiple laser pulse impacts. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
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Open AccessArticle Residual Stress Distribution and Microstructure Evolution of AA 6061-T6 Treated by Warm Laser Peening
Metals 2016, 6(11), 292; doi:10.3390/met6110292
Received: 12 September 2016 / Revised: 11 November 2016 / Accepted: 17 November 2016 / Published: 22 November 2016
Cited by 1 | PDF Full-text (3600 KB) | HTML Full-text | XML Full-text
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
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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. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
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Open AccessArticle Water Droplet Erosion Performance of Laser Shock Peened Ti-6Al-4V
Metals 2016, 6(11), 262; doi:10.3390/met6110262
Received: 20 August 2016 / Revised: 27 September 2016 / Accepted: 24 October 2016 / Published: 3 November 2016
Cited by 2 | PDF Full-text (6841 KB) | HTML Full-text | XML Full-text
Abstract
The water droplet erosion (WDE) performance of laser shock peened (LSP) Ti-6Al-4V was investigated. LSP condition using two or three peening impacts per unit area induced compressive residual stresses. However, LSP treatment showed a mild increase in microhardness and no observable changes in
[...] Read more.
The water droplet erosion (WDE) performance of laser shock peened (LSP) Ti-6Al-4V was investigated. LSP condition using two or three peening impacts per unit area induced compressive residual stresses. However, LSP treatment showed a mild increase in microhardness and no observable changes in the microstructure. The effect of LSP and its associated attributes on the WDE performance was studied according to the American Society for Testing and Materials Standard (ASTM G73). Influence of the impact speed between 150 and 350 m/s on the WDE performance was explored. Two sample geometries, T-shaped flat and airfoil, were used for the WDE tests. For the flat samples, LSP showed little or no beneficial effect in enhancing the WDE performances at all tested speeds. The peened and unpeened flat samples showed similar erosion initiation and maximum erosion rate (ERmax). The LSP airfoil samples showed mild improvement in the WDE performance at 300 m/s during the advanced erosion stage compared to the as-machined (As-M) condition. However, at 350 m/s, no improved WDE performance was observed for the LSP airfoil condition at all stages of the erosion. It was concluded that compressive residual stresses alone are not enough to mitigate WDE. Hence, the notion that the fatigue mechanism is dominating in WDE damage is unlikely. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
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Open AccessArticle Investigation on a Novel Laser Impact Spot Welding
Metals 2016, 6(8), 179; doi:10.3390/met6080179
Received: 29 June 2016 / Revised: 20 July 2016 / Accepted: 28 July 2016 / Published: 3 August 2016
Cited by 4 | PDF Full-text (6985 KB) | HTML Full-text | XML Full-text
Abstract
In this paper a novel laser impact spot welding (LISW) method is described, in which a hump was formed on the flyer plate on the intended welding spot location by local pre-forming. When the flyer and base plates were placed together to perform
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In this paper a novel laser impact spot welding (LISW) method is described, in which a hump was formed on the flyer plate on the intended welding spot location by local pre-forming. When the flyer and base plates were placed together to perform welding, the two plates kept in contact over their entire surfaces except at the hump, where a local air gap was enough to guarantee the impact velocity and collision angle to achieve spot welding using laser pulse energy. The presented approach was implemented to join thin titanium foils to copper foils under low laser energy system. Joints with regular shapes were obtained. The microstructure in the weld interface was studied with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It was found that the jetting occurred at the central region of the weld spots due to oblique impact. Wave features were observed in the weld interfaces. The impact energy was found to have significant influence on the wave’s characteristics. Moreover, SEM images and EDS analysis did not show apparent element diffusion across the weld interface. Besides, the lap shearing test was used to characterize the mechanical properties of the spot welded joints. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
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Open AccessArticle Effects of Warm Laser Peening on Thermal Stability and High Temperature Mechanical Properties of A356 Alloy
Metals 2016, 6(6), 126; doi:10.3390/met6060126
Received: 29 February 2016 / Revised: 20 April 2016 / Accepted: 25 April 2016 / Published: 24 May 2016
Cited by 2 | PDF Full-text (4297 KB) | HTML Full-text | XML Full-text
Abstract
To study the effects of warm laser peening (WLP) on the thermal stability and mechanical properties of A356 alloy, the samples were treated by WLP using a Nd:YAG solid-state laser and temperature control device. The residual stress, micro-hardness and microstructures of samples treated
[...] Read more.
To study the effects of warm laser peening (WLP) on the thermal stability and mechanical properties of A356 alloy, the samples were treated by WLP using a Nd:YAG solid-state laser and temperature control device. The residual stress, micro-hardness and microstructures of samples treated by WLP were observed. The result shows that the temperature significantly affects the strengthening effect of laser peening (LP). The residual stress induced by WLP decreases with the increasing temperature. The micro-hardness and dislocation density increase first, and then decrease with the increases of temperature. The grain refinement degree of the samples treated by WLP is much higher than that of LP. In addition, after aging for 100 min at 220 °C, the samples treated by LP and WLP were comparatively investigated in thermal stability. Obviously, the residual compressive stress, micro-hardness and microstructure induced by WLP present a better thermal stability property than that of LP. The residual stress and micro-hardness of WLP samples are obviously improved, and the increasing degrees are 23.31% and 19.70%, respectively. The dislocation density remains at a high level, while the grains are still in fine crystalline state. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
Open AccessArticle Picosecond Laser Shock Peening of Nimonic 263 at 1064 nm and 532 nm Wavelength
Metals 2016, 6(3), 41; doi:10.3390/met6030041
Received: 12 November 2015 / Revised: 3 February 2016 / Accepted: 5 February 2016 / Published: 23 February 2016
Cited by 3 | PDF Full-text (2762 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents a study on the surface modifications of nickel based superalloy Nimonic 263 induced by laser shock peening (LSP) process. The process was performed by Nd3+:Yttrium Aluminium Garnet (YAG) picosecond laser using the following parameters: pulse duration 170 ps;
[...] Read more.
The paper presents a study on the surface modifications of nickel based superalloy Nimonic 263 induced by laser shock peening (LSP) process. The process was performed by Nd3+:Yttrium Aluminium Garnet (YAG) picosecond laser using the following parameters: pulse duration 170 ps; repetition rate 10 Hz; pulse numbers of 50, 100 and 200; and wavelength of 1064 nm (with pulse energy of 2 mJ, 10 mJ and 15 mJ) and 532 nm (with pulse energy of 25 mJ, 30 mJ and 35 mJ). The following response characteristics were analyzed: modified surface areas obtained by the laser/material interaction were observed by scanning electron microscopy; elemental composition of the modified surface was evaluated by energy-dispersive spectroscopy (EDS); and Vickers microhardness tests were performed. LSP processing at both 1064 nm and 532 nm wavelengths improved the surface structure and microhardness of a material. Surface morphology changes of the irradiated samples were determined and surface roughness was calculated. These investigations are intended to contribute to the study on the level of microstructure and mechanical properties improvements due to LSP process that operate in a picosecond regime. In particular, the effects of laser wavelength on the microstructural and mechanical changes of a material are studied in detail. Full article
(This article belongs to the Special Issue Laser Shock Processing on Metal)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: A study on a 355nm UV-pulsed laser shock processing of polypropylene filled with copper micro-particles
Author: Myung Ju-Kim
Abstract: This study investigated 355nm UV-pulsed laser shock processing of a 150 µm thick film of polypropylene filled with copper particles. Generally, processing polypropylene with a low beam energy UV laser is difficult because the material’s absorption rate is less than 1% in UV wavelengths. However, polypropylene filled with copper particles is easily processed by UV laser, because copper has a UV absorption rate of more than 70%. The absorbed heat of the copper is transmitted to the polypropylene, accomplishing the machining process. Experimental results were observed while changing the laser processing speed rate. Also, the mechanism of the experimental results was investigated theoretically and experimentally.
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