Effects of laser shock peening on the microstructure and fatigue crack propagation behaviour of thin AA2024 specimens

Kashaev, Nikolai; Ventzke, Volker; Horstmann, Μ.; Chupakhin, Sergey; Riekehr, Stefan; Falck, Rielson; Maawad, Emad; Staron, Peter; Schell, Norbert; Huber, N.

doi:10.1016/j.ijfatigue.2017.01.042

Cited by 70 publications

(32 citation statements)

References 18 publications

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“…As the areas for stable crack growth for the specimen without LSP treatment (33%) and the LSP‐treated specimen (33%) are comparable (Figure 9A,B), the effect of LSP could be only attributed to the retardation of the fatigue crack growth. However, in comparison with the propagation of long through‐the‐thickness fatigue cracks, where crack closure is the main mechanism, 30,33,57 any clear indications on crack closure could not be observed in the fractured surfaces of the LSP‐treated specimens investigated in the current study. When analysing details of the SEM‐images of fractured surfaces (areas with a stable fatigue crack growth close to an initial fatigue crack), the specimen without LSP treatment shows very fine fatigue lines and fatigue striations within fatigue crack paths (see Figure 10A).…”

Section: Resultscontrasting

confidence: 58%

“…LSP treatment has a strong beneficial effect on the fatigue performance of structural components because the compressive residual stress field induced in the material considerably retards fatigue crack growth 27–34 . Therefore, a significant improvement in the fatigue behaviour and lifetime prolongation can be achieved for components and structures with surface cracks 27,28,31,34 as well as through‐thickness cracks 29,30,32,33 . Lin et al have investigated the effect of LSP on the fatigue strength of engine components subjected to foreign object damage (FOD), where LSP is applied before FOD 35 .…”

Section: Introductionmentioning

confidence: 99%

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On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

Kashaev

Ushmaev

Ventzke

et al. 2020

Fatigue Fract Eng Mat Struct

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The present study aims to investigate the extent to which the fatigue behaviour of laser beam-welded AA6056-T6 butt joints with an already existing crack can be improved through the application of laser shock peening. Ultrasonic testing was utilized for in situ (nondestructive) measurement of fatigue crack growth during the fatigue test. This procedure allowed the preparation of welded specimens with surface fatigue cracks with a depth of approximately 1.2 mm. The precracked specimens showed a 20% reduction in the fatigue limit compared with specimens without cracks in the as-welded condition. Through the application of laser shock peening on the surfaces of the precracked specimens, it was possible to recover the fatigue life to the level of the specimens tested in the as-welded condition. The results of this study show that laser shock peening is a very promising technique to recover the fatigue life of welded joints with surface cracks, which can be detected by nondestructive testing. K E Y W O R D Saluminium alloys, fatigue crack, laser beam welding, laser shock peening, residual stress, ultrasonic crack tip diffraction

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Section: Resultscontrasting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

Kashaev

Ushmaev

Ventzke

et al. 2020

Fatigue Fract Eng Mat Struct

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“…The comparison to the base material shows that a significant change has taken place due to local plastic deformations induced by the propagating shock waves induced by LP. Kashaev et al [25] reached a similar conclusion. However, different changes in local orientation were observed between the two applied advancing directions.…”

Section: Influence Of Advancing Directionmentioning

confidence: 64%

Effect of Laser Peening Process Parameters and Sequences on Residual Stress Profiles

Kallien

Keller

Ventzke

et al. 2019

Metals

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Laser Peening (LP) is a surface modification technology that can induce high residual stresses in a metallic material. The relation between LP process parameters, in particular laser sequences, as well as pulse parameters and the resulting residual stress state was investigated in this study. The residual stress measurements, performed with the hole drilling technique, showed a non-equibiaxial stress profile in laser peened AA2024-T3 samples with a clad layer for certain parameter combinations. Shot overlap and applied energy density were found to be crucial parameters for the characteristic of the observed non-equibiaxial residual stress profile. Furthermore, the investigation showed the importance of the advancing direction, as the advancing direction influences the direction of the higher compressive residual stress component. The direction of higher residual stresses was parallel or orthogonal to the rolling direction of the material. The effect was correlated to the microstructural observation obtained via electron backscattered diffraction. Additionally, for peening with two sequences of different advancing directions, the study showed that the order of applied advancing directions was important for the non-equibiaxiality of the resulting residual stress profile.

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“…On the other hand, compressive residual stresses introduced by LSP are deeper and higher than by SP [27]. Furthermore, SP causes significant changes in microstructure [28]; however, LSP, in turn, does not lead to such changes [29]. In this regard, the detrimental effect seen for SP when moving from the medium to high cycle fatigue regime is not expected for LSP.…”

Section: Fatigue Testsmentioning

confidence: 93%

The Influence of Laser Shock Peening on Fatigue Properties of AA2024-T3 Alloy with a Fastener Hole

Sikhamov

Fomin

Klusemann

et al. 2020

Metals

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The objective of the present study was to estimate the influence of laser shock peening on the fatigue properties of AA2024-T3 specimens with a fastener hole and to investigate the possibility to heal the initial cracks in such specimens. Fatigue cracks of different lengths were introduced in the specimens with a fastener hole before applying laser shock peening. Deep compressive residual stresses, characterized by the hole drilling method, were generated into the specimens by applying laser shock peening on both sides. Subsequently, the specimens were subjected to fatigue tests. The results show that laser shock peening has a positive effect regarding the fatigue life improvement in the specimens with a fastener hole. In addition, laser shock peening leads to a healing effect on fatigue cracks. The efficiency of this effect depends on the initial crack length. The effect of laser shock peening on the fatigue life periods was determined by using resonant frequency graphs.Metals 2020, 10, 495 2 of 13 and fatigue properties of the aluminum alloy LY12-CZ with various interference values (interference value describes how much a mandrel radius is larger than a hole radius), and it was shown that with increasing interference value from 0% to 6%, the fatigue life increases by a factor of six.Another promising way to improve the behavior of fatigue critical components is laser shock peening (LSP) [7]. LSP is a process in which under the influence of laser pulses, mechanical shock waves arise, propagating under the surface of the material [8]. When the peak pressure of waves exceeds the Hugoniot elastic limit (HEL) of the material, plastic deformation occurs, which leads to compressive residual stresses within the material, i.e., near the surface. The subsurface compressive residual stresses are balanced by the stress field within the material or in zones adjacent to the LSP-treated area. In recent years, various studies have been conducted on the effect of LSP on the fatigue properties of different metallic alloys. Ivetic et al. [9] investigated the effect of the sequence of processes (hole introduction and LSP) on the fatigue properties of AA6082-T6 specimens. The experiments showed that the sequence of processes is important for the improvement of the fatigue life. The beneficial effect of LSP is higher if the hole is introduced after LSP. This is linked to the fact that compressive residual stresses in LSP-treated specimen are compensated by tensile residual stresses [3], and in the case of applying LSP after drilling a hole, the magnitude of tensile stresses would be higher, which would lead to a shorter fatigue life. Achintha et al. [10] evaluated the effect of the size of the LSP-treated area on fatigue properties of AA2024-T3 specimens. Two cases were considered: (i) LSP was performed just around the hole, and (ii) LSP was applied across the entire width of the specimen. The results showed that specimens with a smaller treated area around the hole can withstand more loading cycles than specimens peened along the e...

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Effects of laser shock peening on the microstructure and fatigue crack propagation behaviour of thin AA2024 specimens

Cited by 70 publications

References 18 publications

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

Effect of Laser Peening Process Parameters and Sequences on Residual Stress Profiles

The Influence of Laser Shock Peening on Fatigue Properties of AA2024-T3 Alloy with a Fastener Hole

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