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Article
Publication date: 17 August 2021

Xiaoyu Zhang, Dichen Li and Jiale Geng

Laser cladding deposition is limited in industrial application by the micro-defects and residual tensile stress for the thermal forming process, leading to lower fatigue…

Abstract

Purpose

Laser cladding deposition is limited in industrial application by the micro-defects and residual tensile stress for the thermal forming process, leading to lower fatigue strength compared with that of the forging. The purpose of this paper is to develop an approach to reduce stress and defects.

Design/methodology/approach

A hybrid process of laser cladding deposition and shot peening is presented to transform surface strengthening technology to the overall strengthening technology through layer-by-layer forming and achieve enhancement.

Findings

The results show that the surface stress of the sample formed by the hybrid process changed from tensile stress to compressive stress, and the surface compressive stress introduced could reach more than four times the surface tensile stress of the laser cladding sample. At the same time, internal micro-defects such as pores were reduced. The porosity of the sample formed by the hybrid process was reduced by 90.12% than that of the laser cladding sample, and the surface roughness was reduced by 43.16%.

Originality/value

The authors believe that the hybrid process proposed in this paper can significantly expand the potential application of laser cladding deposition by solving its limitations, promoting its efficiency and applicability in practical cases.

Details

Rapid Prototyping Journal, vol. 27 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 30 August 2011

Peter A. Gaydos and Jeff L. Dulaney

Sacrificial opaque overlays used in laser peening provide optimal processing and protect the surface of the part being processed from thermal damage from the laser pulses…

Abstract

Purpose

Sacrificial opaque overlays used in laser peening provide optimal processing and protect the surface of the part being processed from thermal damage from the laser pulses. Traditional solid film overlays for laser peening often require several applications and the running of multiple partial laser peening sequences in order to completely process the desired surface. This paper aims to discuss an automated overlay system that eliminates these issues.

Design/methodology/approach

LSP Technologies' (LSPT') patented RapidCoater™ automated overlay system provides optimal laser processing and surface protection by providing a conformal opaque layer that is automatically refreshed between each laser pulses. PLC control provides precise timing of the application of the process overlays in synchronization with the laser pulse.

Findings

Use of the RapidCoater system has been shown to reduce processing time by up to five times when compared to using tape overlays. Cost reductions of about 40 percent are also achieved.

Originality/value

LSPT, Inc. invented and developed this proprietary technology to provide its laser peening customers with higher productivity and improved process affordability.

Details

International Journal of Structural Integrity, vol. 2 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 31 May 2011

Goran Ivetic

The aim of this paper is to give a simple and accurate tool for prediction and comparison of residual stresses in laser shock peened and shot peen treated materials.

Abstract

Purpose

The aim of this paper is to give a simple and accurate tool for prediction and comparison of residual stresses in laser shock peened and shot peen treated materials.

Design/methodology/approach

This work applies finite element code ABAQUS in order to compare the residual stress state and plastic deformation in specimens in aluminium alloy 7050‐T7451, treated with shot peening (SP) and laser shock peening (LSP) processes. Both processes are simulated using the Hugoniot elastic limit (HEL) of the material in question, and the processes are modelled using same input parameters (pressure on the surface of the specimen and the duration of contact between the material and the peening medium).

Findings

By using the same approach in both the analyses, a sound comparison of two technologies can be made, by comparing the obtained residual stress profiles. In addition, surface pressure and contact time can be varied easily in a parametric analysis, allowing the calibration of the numerical results.

Research limitations/implications

Owing to simplicity of used numerical models, different process parameters relative to SP process have not been taken in consideration directly, but through their effect on pressure on the surface of the specimen and the duration of contact between the material and the peening medium.

Originality/value

Application of HEL material model, usually applied to LSP problems, to the analysis of SP process gives promising results, in spite of simplicity of used numerical model.

Details

International Journal of Structural Integrity, vol. 2 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 24 August 2012

Gulshan Singh, Juan Ocampo, Harry Millwater and Allan Clauer

The purpose of this paper is to develop an approach to optimize the cycles‐to‐failure of a peened component with respect to laser peening (LP) variables: pressure…

Abstract

Purpose

The purpose of this paper is to develop an approach to optimize the cycles‐to‐failure of a peened component with respect to laser peening (LP) variables: pressure magnitude, mid‐span, and spot size when the component is subject to a variable amplitude loading.

Design/methodology/approach

To optimally design an LP process, an experimentally validated 3D finite element simulation of the LP process, a cycles‐to‐failure estimation capability incorporating residual stress, and a particle swarm optimization strategy were developed and employed to maximize the cycles‐to‐failure of a component of a titanium turbine disk.

Findings

The most critical finding of this research is that a minor difference in the residual stress profile can lead to a large difference in the cycles‐to‐failure. This finding implies that selecting the optimization objective to be the cycles‐to‐failure is a better option as compared to the residual stress profile.

Research limitations/implications

The LP‐induced residual stresses are assumed static and do not change as number of load cycles increase.

Originality/value

The paper develops a framework that relates the LP variables and the cycles‐to‐failure of a peened component. A modified particle swarm optimization approach is developed to optimize the fatigue life of a turbine disk.

Article
Publication date: 8 March 2011

Uroš Trdan, Sebastjan Žagar, Janez Grum and José Luis Ocan˜a

The purpose of this paper is to investigate the effect of shock waves and strain hardening effect of laser and shot peening on precipitation‐hardened aluminium alloy AA 6082‐T651.

Abstract

Purpose

The purpose of this paper is to investigate the effect of shock waves and strain hardening effect of laser and shot peening on precipitation‐hardened aluminium alloy AA 6082‐T651.

Design/methodology/approach

The hardened layer was evaluated by means of surface integrity with optical microscopy, scanning electron microscope (SEM), energy dispersive spectroscopy, analysis of microhardness and residual stress profiles. Corrosion anodic polarization tests in a 3.5 per cent NaCl water solution were carried out to express a pitting potential and the degree of pitting attack, which was verified on SEM and with 3D metrology.

Findings

Research results indicated significant differences between two treatment techniques which had an important influence on the final condition of the surface layer. Potentiodynamic polarization tests inferred that laser peening enabled shift of the pitting potential to more positive values, which ensures higher corrosion resistance.

Originality/value

Results confirmed that the higher corrosion resistance of the laserpeened specimens against pitting corrosion depends on the modification of the surface, due to ablation during plasma generation. Despite increased surface roughness, laserpeened specimen exhibits beneficial increase of the pitting/breakdown potential and in reduction of pitting attack degree at the specimen surface.

Details

International Journal of Structural Integrity, vol. 2 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 8 March 2011

Yuji Sano, Koichi Akita, Kazuya Takeda, Rie Sumiya, Toshiyuki Tazawa, Toshiyuki Saito and Chihiro Narazaki

The purpose of this paper is to investigate the behavior of compressive residual stress induced by laser peening under external loading on an age‐hardened high‐strength…

Abstract

Purpose

The purpose of this paper is to investigate the behavior of compressive residual stress induced by laser peening under external loading on an age‐hardened high‐strength aluminum alloy A2024‐T3, a low‐carbon austenitic stainless steel SUS316L (Type 316L) and a nickel‐based alloy NCF600 (Alloy 600).

Design/methodology/approach

The surface residual stress was measured intermittently by X‐ray diffraction during cyclic uniaxial loading.

Findings

The compressive residual stress due to laser peening significantly decreased during the first few cycles at stress ratio of 0.1 with the maximum loading stress exceeding the 0.2 per cent yield stress. No remarkable decrease was observed afterward until the end of the loading cycles.

Originality/value

Under symmetric loading at the stress ratio of −1 to A2024‐T3, a major decrease took place in the compression side of the first loading cycle. The surface residual stresses remained in compression within all the extent of the present experiments, even if the maximum loading stress exceeded the yield stress of the materials.

Details

International Journal of Structural Integrity, vol. 2 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 31 May 2011

Lothar Wagner, Mansour Mhaede, Manfred Wollmann, Igor Altenberger and Yuji Sano

The purpose of this paper is to investigate the influence of mechanical surface treatments on the surface layer properties and the fatigue performance of the aircraft…

1280

Abstract

Purpose

The purpose of this paper is to investigate the influence of mechanical surface treatments on the surface layer properties and the fatigue performance of the aircraft alloys Al 7075‐T73 and Ti‐6Al‐4V

Design/methodology/approach

Laser peening without coating (LPwC), shot peening (SP), ultrasonic shot peening (USP) and ball burnishing (BB) were applied and the resulting changes in surface roughness and residual stress‐depth profiles were evaluated. Fatigue performance of both alloys was tested in rotating beam loading (R=−1) on hourglass‐shaped specimens and the results were compared with the electrolytically polished (EP) reference conditions.

Findings

All studied mechanical surface treatments led to pronounced increases in fully reversed fatigue lives and fatigue strengths in both Al 7075‐T73 and Ti‐6Al‐4V.

Originality/value

To the authors' knowledge, this is the first paper that compares fatigue performance of a wide variety of mechanically surface treated conditions in two aircraft alloys.

Details

International Journal of Structural Integrity, vol. 2 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 8 March 2011

Dennis J. Buchanan, Michael J. Shepard and Reji John

The purpose of this paper is to analyze the residual stress relaxation in laser shock‐peened and shot‐peened IN100 subject to thermal exposure.

544

Abstract

Purpose

The purpose of this paper is to analyze the residual stress relaxation in laser shock‐peened and shot‐peened IN100 subject to thermal exposure.

Design/methodology/approach

Shot peening (SP) is a commonly used surface treatment that imparts compressive residual stress into the surface of components. The shallow depth of compressive residual stresses, and the extensive plastic deformation associated with SP, has been overcome by modern approaches such as laser shock peening (LSP). LSP surface treatment produces compressive residual stress magnitudes that are similar to SP that extend four to five times deeper, and with less plastic deformation. Retention of compressive surface residual stresses is necessary to retard initiation and growth of fatigue cracks under elevated temperature loading conditions.

Findings

Results indicated that the LSP processing retains a higher percentage of the initial residual stress profile over that of SP.

Originality/value

The retained residual stresses after thermal exposure of these surface treatment processes can be incorporated into a life prediction methodology that takes credit for beneficial compressive surface residual stresses to delay initiation and retard fatigue crack growth.

Details

International Journal of Structural Integrity, vol. 2 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 6 August 2019

Yongxiang Hu, Mengqi Lai, Zonghao Hu and Zhenqiang Yao

Laser additive manufacturing is widely utilized to fabricate the Ti6Al4V alloy, but it requires post-processing to improve its performance. This paper aims to propose laser

Abstract

Purpose

Laser additive manufacturing is widely utilized to fabricate the Ti6Al4V alloy, but it requires post-processing to improve its performance. This paper aims to propose laser peening (LP) as an effective way to improve the surface characteristics of the Ti6Al4V alloy fabricated by direct laser deposition (DLD).

Design/methodology/approach

Surface integrity including surface roughness, porosity, residual stress and microhardness are investigated in detail before and after LP treatment. Microstructure evolution is characterized by the electron backscatter diffraction (EBSD) to analyze crystal phase, grain boundary misorientation and texture.

Findings

Multiple overlapping layers of LP treatment result in slight influence on the polished surface of DLD-built samples. Porosity measured by the Archimedes test is found to be greatly decreased after LP treatment. Compressive residual stresses are significantly induced, the magnitude of which is greatly increased by increasing layers of LP treatment. And, local weakening or enhancement of residual stress in depth is observed because of pore and inclusion defects in the DLD-built Ti6Al4V alloy. Favorable hardness property can be obtained after multiple overlapping layers of LP treatment. EBSD analysis shows that LP treatment with multiple layers can introduce a large amount of lower-angle boundaries, indicating that dislocations beneath the top surface could induce a strain-hardened layer. The microtexture of the DLD-built Ti6Al4V alloy cannot be eliminated to decrease the anisotropy of the mechanical property.

Research limitations/implications

The variation of porosity observed after LP inside the DLD-built Ti-Al-4V is attractive but requires more detailed work to analyze the evolution of pore geometry.

Practical implications

Surface treatment of an additive manufactured titanium alloy was carried out to improve its fatigue resistance.

Originality/value

This work is original in proposing LP as an effective post process for the surface treatment of an additive manufactured titanium alloy through analyzing the surface integrity and microstructure evolution.

Details

Rapid Prototyping Journal, vol. 25 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 August 2005

A. Tolga Bozdana

To review the most commonly used mechanical surface enhancement (MSE) techniques and their applications available in aerospace industry.

6424

Abstract

Purpose

To review the most commonly used mechanical surface enhancement (MSE) techniques and their applications available in aerospace industry.

Design/methodology/approach

A brief description of each technique, as well as advantages and disadvantages over other techniques are given. The effects of those techniques on the surface characteristics and service properties of treated components are summarised. Finally, the applications of such techniques in the aerospace industry are presented with descriptive illustrations.

Findings

Provides a know‐how information and also comparison of techniques. Guides researchers and engineers to proper and appropriate use of each technique for relevant case or application.

Research limitations/implications

The list of techniques can be extended to a wider range which may perhaps include specific and special purpose surface enhancement methods. The applications given in the paper are mainly industrial examples of such techniques which may reduce its usefulness in academia.

Practical implications

A very useful source of information and reference for companies and engineers working in repair and production technologies of aerospace components, and also a valuable guidance for researchers and academia or for those who are intending to make a research on surface enhancement technologies.

Originality/value

This paper introduces the most commonly used MSE techniques and their effects on the service properties of aerospace components, and provides a practical help and information for people in the industry and academia.

Details

Aircraft Engineering and Aerospace Technology, vol. 77 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

1 – 10 of 158