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Article
Publication date: 31 January 2020

R.G. Song, T.S. Hua, Y. Zong and S.W. Cai

This paper aims to study the effect of Micro-arc oxidation (MAO) coating on stress corrosion and electrochemical behavior of aluminum alloy.

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Abstract

Purpose

This paper aims to study the effect of Micro-arc oxidation (MAO) coating on stress corrosion and electrochemical behavior of aluminum alloy.

Design/methodology/approach

The stress corrosion cracking behavior of 7050 aluminum alloy (AA7050) after MAO treatment was investigated in 3.5 Wt.% NaCl solution using the constant load ring. Electrochemical impedance spectroscopy (EIS) was used to evaluate the change of corrosion resistance of MAO specimens in 3.5  Wt.% NaCl solution, and appropriate equivalent circuits were established.

Findings

The results demonstrated that the MAO coating can improve the corrosion resistance of the AA7050 and avoid the reduction of mechanical properties caused by corrosion. In the initial stage of corrosion, the corrosion resistance of coated specimen decreased at first and then increased. In the middle and final stage of corrosion, the corrosion resistance of coated specimen decreased at first and then stabilized.

Originality/value

The long-term corrosion behavior of MAO specimens under stress was studied by constant load experiment and EIS. It has guiding significance for the application of MAO technology on aluminum alloy.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 30 August 2011

Simon A. Barter

This paper aims to present some aspects associated with the life prediction of structures with fatigue cracks growing from small natural discontinuities in aluminium alloy…

Abstract

Purpose

This paper aims to present some aspects associated with the life prediction of structures with fatigue cracks growing from small natural discontinuities in aluminium alloy (AA)7050‐T7451 for a surface condition that is present in F/A‐18 A/B aircraft critical structure.

Design/methodology/approach

Fatigue results are presented for thick section AA7050 plate coupons loaded with a representative fighter aircraft wing root bending moment loading spectrum. Detailed quantitative fractography (QF) was used to gain a deeper understanding of issues relevant to an improved fatigue life predictive capacity for this material by using the QF results to investigate the “effectiveness” of the fatigue initiating discontinuities.

Findings

Estimates of the “effectiveness” of the fatigue initiating discontinuities as quasi pre‐existing fatigue cracks (“equivalent pre‐crack size” (EPS) here) were made with the aid of a simple crack growth model. This model, based on experience, was found to be valid for the applied spectrum and stress levels used. These stress levels were chosen to represent those that may be found in highly stressed locations of fighter aircraft; and as such would usually lead to the limiting fatigue life of such a structure.

Research limitations/implications

The method has been extended to other crack growth situations and is being used to build a database large enough to determine the best probability distribution of the “effectiveness” of the fatigue initiating discontinuities for not only the surface condition reported here but several other surface conditions typical of aircraft metallic structure.

Practical implications

The EPS of the discontinuities from which the cracks grew were used to investigate distributions that may be used in a risk‐based assessment using deterministic crack growth measurements from such discontinuities. Some of the problems that remain to be resolved in such an analysis, prior to its use in a risk‐based assessment are discussed.

Originality/value

This work improves the understanding of the interaction of small fatigue cracks generated by representative loading spectra with the small discontinuities from which they grow and shows that the fatigue process is remarkably consistent down to very small sizes.

Details

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

Keywords

Article
Publication date: 8 March 2011

Ulrike C. Heckenberger, Elke Hombergsmeier, Vitus Holzinger and Wolfgang von Bestenbostel

Laser shock peening (LSP) is a process capable of introducing compressive residual stresses into a metallic component. The residual compressive stress field can extend deeper…

Abstract

Purpose

Laser shock peening (LSP) is a process capable of introducing compressive residual stresses into a metallic component. The residual compressive stress field can extend deeper below the treated surface than that produced by conventional shot peening (SP). The effect of such deep compressive stress profile is expected to result in a significantly greater benefit in fatigue resistance after LSP compared to SP. The purpose of this paper is to examine this further.

Design/methodology/approach

Residual stress profiles have been determined by X‐ray diffraction and incremental centre hole drilling. They have been correlated with the respective LSP process parameters and the obtained fatigue behavior.

Findings

A significant improvement of the fatigue life was found for an R ratio of 0.1. SP leads to a fatigue improvement of about 15 percent. For the same specimen geometry, a fatigue life improvement of about 25‐35 percent, depending on the load level, can be obtained after LSP. However, not only for the positive R ratio, where it is quite obvious, but also for the negative R ratios, R=−1 and −3, an increase of the fatigue life is generated by SP and LSP.

Originality/value

A shown LSP has a high potential for extending the service life of metallic components at the design stage, but it may also be possible to apply this technique to in‐service aircraft to extend the service goals of existing structures.

Details

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

Keywords

Article
Publication date: 7 June 2021

Ranjith R. and S. Nalin Vimalkumar

The most difficult tasks in the design and development of products for diverse engineering applications were the selection of suitable materials. Choice of inappropriate process…

Abstract

Purpose

The most difficult tasks in the design and development of products for diverse engineering applications were the selection of suitable materials. Choice of inappropriate process variables leads to poor performance, which increases the cost of the product. The selection of the best option of available alternatives is important to improve the performance and productivity of the manufacturing enterprises.

Design/methodology/approach

The paper aims to develop Hybrid Multi-Criteria Decision Making (HMCDM) by integrating two potential optimization techniques Elimination Et Choix Traduisant la REalité and multi-objective optimization on the basis of ratio analysis. The weight of the criteria was calculated using the critic weight method.

Findings

The efficiency and flexibility of the proposed HMCDM technique were illustrated and validated by two examples. In the first case, the best electrode material among the five available alternatives was selected for the electrical discharge machining of AZ91/B4Cp magnesium composites. In the second case, the optimum weight percentage of composites providing the best tribological properties was chosen.

Originality/value

It was noted that the HMCDM methodology was quite simple to comprehend, easy to apply and provided reliable rankings of the material alternatives. The proposed hybrid algorithm is suitable for product optimization as well as design optimization.

Details

World Journal of Engineering, vol. 19 no. 4
Type: Research Article
ISSN: 1708-5284

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: 23 September 2020

Ashish Kumar Srivastava, Brijesh Sharma, Bismin R. Saju, Arpit Shukla, Ambuj Saxena and Nagendra Kumar Maurya

The development of a new class of engineering materials is the current demand for aircraft and automobile companies. In this context metal, composite materials have a widespread…

Abstract

Purpose

The development of a new class of engineering materials is the current demand for aircraft and automobile companies. In this context metal, composite materials have a widespread application in different areas of manufacturing sectors.

Design/methodology/approach

In this paper, an attempt is made to develop the aluminium-based nano metal matrix composite reinforced with graphene nanoparticles (GNP) by using the stir casting method. Different weight percentage (0.4%, 0.8% and 1.2% by weight) of GNPs are used to fabricate metal matrix composites (MMCs). The developed nanocomposites were further validated by density calculation and optical microstructures to discuss the distribution of GNPs. The tensile test was conducted to determine the strength of the developed MMCs and also supported by fractographic analysis. In addition to it, the Rockwell hardness test and impact test (toughness) with fracture analysis were also conducted to strengthen the present work.

Findings

The results reveal the uniform distribution of GNPs into the matrix material. The yield strength and ultimate tensile strength obtained a maximum value of 155.67 MPa and 170.28 MPa, respectively. The hardness value (HRB) is significantly increased and 84 HRB was obtained for the sample with AA1100/0.4% GNP, while maximum hardness value (94 HRB) was obtained for the sample AA1100/1.2% GNP. The maximum value of toughness 14.3 Jules/cm2 is recorded for base alloy AA1100 while increasing the reinforcement percentage, it decreases up to 9.7 Jules/cm2 for AA1100/1.2% GNP.

Originality/value

Graphene nanoparticles are used to develop nanocomposites, which is one of the suitable alternatives for heavy engineering materials such as steels and cast irons. It has improved microstructural and mechanical properties which makes it preferable for many engineering and structural applications.

Details

World Journal of Engineering, vol. 17 no. 6
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 28 October 2019

Rajesh Kumar Bhushan and Deepak Sharma

Sound microstructure components are necessary for reliability and safety; hence, these components are used in aircraft, satellite, automobiles and ships, where many commercial…

Abstract

Purpose

Sound microstructure components are necessary for reliability and safety; hence, these components are used in aircraft, satellite, automobiles and ships, where many commercial alloys are not suitable. The paper aims to discuss this issue.

Design/methodology/approach

AA6082/Si3N4 and AA6082/SiC composites were fabricated using the stir-casting process considering 5, 10 and 15 vol.% of reinforcement particles. Density and porosity of AA6082/Si3N4 and AA6082/SiC composites were calculated. Characterization was done using an X-ray (EDX) detector, attached to SEM. The effect of addition of Si3N4 and SiC particulates in the AA6082 was investigated.

Findings

Results showed that Si3N4 and SiC particulates had good wettability with AA6082 and were uniformly distributed in AA6082 matrix. No adverse effects of reactions were noticed in the microstructure of AA6082/Si3N4 and AA6082/SiC composites.

Research limitations/implications

AA6082 with more than 15 vol.% of Si3N4 and AA6082/SiC reinforcement particles do not find industrial application where high hardness and tensile strength are required.

Practical implications

Components made from AA6082/Si3N4 and AA6082/SiC composites find their application where high hardness with better tensile strength is required.

Social implications

Naturally and locally available materials are utilized for fabrication.

Originality/value

Little work is available in the literature on fabrication and characterization of AA6082/Si3N4 and AA6082/SiC composites. The authors have identified the process parameters at which proper fabrication is done and sound microstructure is obtained.

Details

International Journal of Structural Integrity, vol. 11 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 30 August 2011

Qianchu Liu, Madabhushi Janardhana, Bruce Hinton, Milan Brandt and Khan Sharp

The purpose of this paper is to demonstrate the preliminary work on using laser cladding technology for the restoration of structural integrity.

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Abstract

Purpose

The purpose of this paper is to demonstrate the preliminary work on using laser cladding technology for the restoration of structural integrity.

Design/methodology/approach

The primary methodology used in this research is to develop a laser cladding‐based metal deposition technique to articulate restoration of structural geometry affected by corrosion damages. Following from this method, it is planned to undertake further work to use the laser cladding process to restore geometry and the associated static/fatigue strength.

Findings

This work has found that it is possible to use laser cladding as a repair technology to improve structural integrity in aluminium alloy aircraft structures in terms of corrosion reduction and geometrical restoration. Initial results have indicated a reduction of static and fatigue resistance with respect to substrate. But more recent works (yet to be published) have revealed improved fatigue strength as measured in comparison to the substrate structural properties.

Originality/value

The research is based on an acceptable materials processing technique.

Details

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

Keywords

Article
Publication date: 16 October 2023

Y.F. Shu, B. Jiang, C. Wang and R.G. Song

The purpose of this paper is to study the effects of voltage on microstructure and properties of micro-arc oxidation (MAO) ceramic coatings formed on AZ31B magnesium alloy under…

Abstract

Purpose

The purpose of this paper is to study the effects of voltage on microstructure and properties of micro-arc oxidation (MAO) ceramic coatings formed on AZ31B magnesium alloy under the constant current–constant voltage operation mode.

Design/methodology/approach

The wear and corrosion resistance of MAO coating on AZ31B magnesium alloy was studied by MAO in silicate electrolyte under constant current and constant voltage.

Findings

When the voltage is 360 V, the wear and corrosion resistance of AZ31B magnesium alloy is the best.

Originality/value

The wear and corrosion resistance of MAO coating on AZ31B magnesium alloy was studied by friction wear and electrochemical workstation.

Details

Anti-Corrosion Methods and Materials, vol. 70 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 23 September 2022

Yuting Lv, Jiawei Guo, Weimin Huang, Yaojie Liu, Wentao Liu and Guijiang Wei

The purpose of this paper is to improve the bioactivity of variable gradient TC4 porous scaffolds prepared by selective laser melting (SLM) through the micro-arc oxidation (MAO…

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Abstract

Purpose

The purpose of this paper is to improve the bioactivity of variable gradient TC4 porous scaffolds prepared by selective laser melting (SLM) through the micro-arc oxidation (MAO) technique.

Design/methodology/approach

Variable gradient TC4 porous scaffolds were prepared by SLM, then treated with MAO at different oxidation voltages. The microstructure, thickness and composition of MAO coatings were characterized by scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction. The bioactivity of the MAO coatings was tested by simulated body fluid (SBF) immersion test.

Findings

SEM and EDS results show that with the increase of oxidation voltage, the content of Ca and P elements and the thickness of the MAO coatings increases. The thickness of the coating inside the scaffold is smaller than that of the outside regions. SBF immersion experiments showed that MAO-treated TC4 porous scaffolds had highest bioactivity at 440 V.

Originality/value

The variable gradient porous scaffolds were treated with MAO in the electrolyte containing Ca and P elements for the first time. The effect of oxidation voltages on the different region of porous scaffolds was studied in detail.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

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