Compressive Residual Stress Evolution Process by Laser Peening

Residual stress induced by laser single pulse irradiation was analyzed using a dynamic finite element code, ABAQUS/Explicit. The effects of the magnitude and length of a surface pressure pulse having a circular top-hat shape on the final residual stress in Ti-6Al-4V were investigated. A high peak pressure and/or a long pulse duration was effective in generating large compressive residual stress deep beneath the surface. However, large tensile residual stress features occurred near the centre and edge of the laser spot on the surface for high pressure and/or long pulse durations due to a radial focusing effect. Use of shorter pulse durations avoided this. The peak pressure (3GPa) required to induce a surface compressive residual stress across the whole area of the spot was slightly higher than the threshold pressure needed to plastically deform the surface.

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Optimization of Laser Peening Parameters Using Taguchi Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.10-12.692 ◽

2007 ◽

Vol 10-12 ◽

pp. 692-696 ◽

Cited By ~ 2

Author(s):

Yue Qing Sun ◽

Jian Zhong Zhou ◽

Yi Bin Chen ◽

Shu Huang

Keyword(s):

Residual Stress ◽

Taguchi Method ◽

Compressive Stress ◽

Compressive Residual Stress ◽

Residual Compressive Stress ◽

Critical Parameters ◽

Laser Peening ◽

The Finite Element Method ◽

Optimal Setting ◽

The Impact

Using Taguchi method to optimize the critical parameters of laser peening (LP) is presented firstly. The objective of the study is to assess the impact of laser parameters on the laser peen strengthening for the 6061-T6 aluminum alloy and optimize the process parameters to achieve higher surface residual compressive stress. In order to reduce the process cost and time, the finite element method was applied to simulate the LP process. The Taguchi method is used to formulate the experimental layout and establish the order of predominance among the identified critical parameters, and predict the optimal setting for each process parameter. The results show that three parameters related to the magnitude of compressive residual stress imply different effects. Laser shot diameter ranks first, followed by pulse width and laser power in terms of their effects on the magnitude of compressive residual stress. The best combination of levels is given by the levels (3, 3, 2). The optimal result was confirmed with a superior ultimate surface residual compressive stress of 125MP.

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Application of Indirect Laser Peening to SUS304 Stainless Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.783-786.2316 ◽

2014 ◽

Vol 783-786 ◽

pp. 2316-2321

Author(s):

Hiroshi Kawakami ◽

Akiyoshi Kondo ◽

Muneharu Kutsuna ◽

Kiyotaka Saito ◽

Hiroki Inoue ◽

...

Keyword(s):

Residual Stress ◽

Stainless Steel ◽

Austenitic Stainless Steel ◽

Stress Distribution ◽

Pulse Energy ◽

Laser Power ◽

Compressive Residual Stress ◽

Residual Stress Distribution ◽

Bending Test ◽

Laser Peening

Indirect laser peening applied to the substrate of austenitic stainless steel with the sheet of similar material. Effects of indirect laser peening condition on the formation of the dimple and the residual stress were investigated in this paper. Shape of the dimple and distribution of the residual stress were measured by laser microscope and X-ray diffraction, respectively. It was observed by the microscope that clean substrate surface of as-received state kept after indirect laser peening because of protection by the sheet. However, fracture of sheet occurred slightly in high pulse energy condition. The diameter and the depth of the dimple by indirect laser peening increased with the increase of laser power. Efficiency of dimple formation decreased with the increase of pulse energy. Affective condition region of indirect laser peening with a combination between the substrate and the sheet of austenitic stainless steel may be limited below the laser power density of 10GW/cm2. It was confirmed that indirect laser peening induced compressive residual stress in the substrate. One of peak of compressive residual stress in residual stress distribution existed near the bottom of the dimple. Residual stress distribution which was produced by indirect laser peening may affect change of quasi bending modulus which was obtained by three-point bending test.

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OS1434 Effect of Applied Stress on the Compressive Residual Stress after Laser Peening

The Proceedings of the Materials and Mechanics Conference ◽

10.1299/jsmemm.2009.340 ◽

2009 ◽

Vol 2009 (0) ◽

pp. 340-342 ◽

Cited By ~ 1

Author(s):

Rie SUMIYA ◽

Toshiyuki TAZAWA ◽

Chihiro NARAZAKI ◽

Toshiyuki SAITO

Keyword(s):

Residual Stress ◽

Applied Stress ◽

Compressive Residual Stress ◽

Laser Peening

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Effects of Laser Peening Treatment on High Cycle Fatigue and Crack Propagation Behaviors in Austenitic Stainless Steel

Volume 1: Plant Operations, Maintenance, Engineering, Modifications and Life Cycle; Component Reliability and Materials Issues; Next Generation Systems ◽

10.1115/icone17-75821 ◽

2009 ◽

Author(s):

Yasuo Ochi ◽

Kiyotaka Masaki ◽

Takashi Matsumura ◽

Takaaki Ikarashi ◽

Yuji Sano

Keyword(s):

Residual Stress ◽

Stainless Steel ◽

Surface Layer ◽

Fatigue Crack ◽

Fatigue Strength ◽

Crack Propagation ◽

Compressive Residual Stress ◽

High Cycle Fatigue ◽

Laser Peening ◽

Cycle Fatigue

Laser peening without protective coating (LPwC) treatment is one of surface enhancement techniques using impact wave of high pressure plasma induced by laser pulse irradiation. One of the effects of the LPwC treatment is expected to reduce the tensile residual stress and to induce the compressive residual stress in the surface layer of metallic materials. As a laser has no reaction force due to irradiation and also it has easy characteristics for remote control, the LPwC treatment is practically used as a technique for preventing the stress corrosion cracking (SCC) and for improving the fatigue strength of some structural materials. In this study, high cycle fatigue tests with four-points rotating bending loading were carried out on the non-peened and the LPwC treated low-carbon type austenitic stainless steel 316L in order to investigate the effects of the LPwC treatment on the high cycle fatigue strength and the surface fatigue crack propagation behavior. Two types of specimens were prepared; one was a smooth specimen, the other was a specimen with a pre-crack by the fatigue loading from a small artificial hole. As the results of the LPwC treatment, the high compressive residual stress was induced in the surface layer on the specimens, and the region of the compressive residual stress was about 1mm depth from the surface. The fatigue strength of the LPwC treated SUS316L was remarkably improved during the whole regime of the fatigue life up to the 108 cycles compared with the non-peened materials. Through the fracture mechanics investigation of the pre-cracked materials after the LPwC treatment, it became clear that the fatigue crack propagation was restrained by the LPwC treatment on the pre-cracked region, when the stress intensity factor range ΔK on the crack tip was under the value of 7.6 MPa√m.

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Effects of laser peening on fretting wear behaviour of alloy 718 fretted against two different counterbody materials

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650117692707 ◽

2017 ◽

Vol 231 (10) ◽

pp. 1276-1288 ◽

Cited By ~ 4

Author(s):

S Anand Kumar ◽

R Sundar ◽

S Ganesh Sundara Raman ◽

R Gnanamoorthy ◽

R Kaul ◽

...

Keyword(s):

Residual Stress ◽

Surface Roughness ◽

Compressive Residual Stress ◽

Tangential Force ◽

Fretting Wear ◽

Wear Behaviour ◽

Laser Peening ◽

Alloy 718 ◽

Force Coefficient ◽

Near Surface

This paper deals with the effects of laser peening on fretting wear behaviour of a nickel-based superalloy, alloy 718, fretted against two different counterbody materials (alumina and SAE 52100 steel). Laser peening was carried out on alloy 718. Microstructural characterization of laser peened surface was done by electron back-scattered diffraction and transmission electron microscopy. Surface roughness, nanoindentation hardness, and residual stress of both laser peened and unpeened samples were determined. Fretting wear tests were conducted on unpeened and laser peened samples using two different counterbody materials (alumina and SAE 52100 steel balls). The results show that nanocrystallites formed in the surface and near-surface regions and compressive residual stress were induced after laser peening. Hardness increased due to grain refinement at the surface and near-surface regions. There was no significant change in the surface roughness. The laser peened sample exhibited lower tangential force coefficient values compared to unpeened samples at all loads, which may be attributed to higher hardness. Samples fretted against alumina counterbody exhibited higher tangential force coefficient compared to samples fretted against steel counterbody. Owing to increased surface hardness and higher compressive residual stress, laser peened samples exhibited lower fretting wear damage compared to unpeened samples. Due to tribochemical reactions, the wear volume of unpeened and laser peened samples fretted against alumina counterbody was higher than that of the samples fretted against steel counterbody.

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Improvement in Bending Strength of Silicon Nitride through Laser Peening

Materials ◽

10.3390/ma15010315 ◽

2022 ◽

Vol 15 (1) ◽

pp. 315

Author(s):

Kazuya Saigusa ◽

Joji Yamamoto ◽

Koji Takahashi ◽

Fumiaki Kumeno ◽

Norihito Shibuya

Keyword(s):

Residual Stress ◽

Surface Roughness ◽

Silicon Nitride ◽

Compressive Residual Stress ◽

Bending Strength ◽

Fracture Initiation ◽

Laser Peening ◽

Initiation Point

This study aimed to improve the bending strength and reliability of ceramics using laser peening (LP). In the experiment, LP without coating (LPwC) and with coating (LPC) were applied to silicon nitride (Si3N4) under various conditions. The surface roughness, residual stress, and bending strength were then measured for the non-LP, LPwC, and LPC specimens. The results show that the LPwC specimen had a greater surface roughness but introduced larger and deeper compressive residual stress when compared with the non-LP and LPC specimens. In addition, the bending strength of the LPwC specimen was higher and scatter in bending strength was less compared with the non-LP and LPC specimens. This may be attributed to the transition of the fracture initiation point from the surface to the interior of the LPwC specimen because of the compressive residual stress introduced near the surface. Thus, it was demonstrated that the application of LP is effective in improving the strength and reliability of ceramics.

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