On the fatigue performance of laser hybrid welded high Zn 7000 alloys for next generation railway components

Wu, Shengchuan; Hu, Yuqing; Duan, Hua; Chen, Yu; Jiao, Haitao

doi:10.1016/j.ijfatigue.2016.05.017

Cited by 75 publications

(34 citation statements)

References 35 publications

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“…As for pore sphericity, the larger the spherical value, the more regular and round the pore. It is also found that metallurgical pores tend to be a sphericity of 0.60 or so . As for pore distribution, it is clear from both Figures and that larger porosity and relatively smaller porosity are located at the upper and lower parts of the hybrid joints, respectively.…”

Section: Experiments and Simulationsmentioning

confidence: 70%

“…Peak‐hardened 7000 series aluminum alloys conventionally used into aerospace industries have currently been attempted for high‐speed railway components, such as sleeper beams, axle boxes, and pantographs . To improve the structural integrity, more attentions should be paid on the higher fatigue resistance of such high‐strength alloys due to welding, casting, and 3D printing . However, defects such as gas pores and hot cracks cannot be completely eliminated by high energy density beam welding despite subjected to optimum processing parameters and suitable filler metals .…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, industrial X‐ray cannot correctly identify such small‐sized bulk defects particularly beneath the surface . Hence, the intrinsic aspects of internal defects throw a great challenge to the safety assessment of fusion welded Al alloy structures under fatigue loading …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Song

Ding³

et al. 2019

Fatigue Fract Eng Mat Struct

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Defect or shrinkage is known to have a detrimental effect on the fatigue resistance of casting lightweight alloys and additively manufactured or 3D printed materials. However, very few works focus on the damage mechanism of fusion welded Al alloys due to gas pores or metallurgical defects. This paper performs an investigation on the effect of porosity on the damage evolution of laser hybrid welded 7020‐T651 alloys. The critical pore size comparable with average weld grain was assumed in terms of the population and dimension of micropores. To characterize the coupling effect between gas pores and cracks, an in situ fatigue testing rig was developed to well work at the synchrotron radiation tomography system. Combining synchrotron X‐ray microtomography and fatigue resistance testing, the pore size and location were correlated with the crack initiation and crack growth path but relatively less on the long crack propagation rate. Furthermore, the interaction between the porosity and stress concentration was elucidated by using finite element simulations, which shows that the gas pore appears to be a preferred cracking site especially near the surface.

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Section: Experiments and Simulationsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Song

Ding³

et al. 2019

Fatigue Fract Eng Mat Struct

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show abstract

“…Softening in the FZ was caused by microstructural changes as a result of very high temperatures experienced in the FZ and the associated rapid heating and cooling rates during welding. The heating action of the laser led to segregation of the strengthening elements, magnesium and copper, and their hybrids (intermetallic compounds), formation and growth of nonstrengthening coarse precipitates, dissolution of strengthening precipitates and uniform re-distribution of precipitating elements during heating which then froze due to fast cooling rates [32]. In addition, softening can also be attributed to violent vaporization of low boiling point magnesium and element variation resulting from the filler dilution [33] as observed in Figure 5 a) showing lower Cu and Mg contents with increasing filler metal feed rate.…”

Section: Micro-hardnessmentioning

confidence: 99%

Effect of filler metal feed rate and composition on microstructure and mechanical properties of fibre laser welded AA 2024-T3

Ahn

Chen

et al. 2017

Journal of Manufacturing Processes

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“…Besides, autogenous laser beam welding is unsuitable to weld 7020 Al alloys mainly due to high reflectivity . The hybrid laser‐arc welding (HLW) method was therefore developed by Steen and Eboo in 1979, showing great potential to Al alloys with more stable welding process, deeper weld penetration, and larger gap tolerance …”

Section: Introductionmentioning

confidence: 99%

Effect of microstructural features on the failure behavior of hybrid laser welded AA7020

Song

et al. 2018

Fatigue Fract Eng Mat Struct

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Detailed investigations of microstructural feature, mechanical property, fatigue strength, and damage mechanism were conducted on hybrid laser welded 7020‐T651 aluminum alloys used into high‐speed railway vehicles. The results show that the hybrid laser welding process can induce significant changes of microstructures and alloying elements, together with numerous gas pores. Such local modifications degrade the fatigue performance. The tensile strength of welded joints was approximately 74% with respect to the base metal, thus satisfying the design standard. The fatigue property was determined in the low and high cycle regimes. It was found that the fatigue strength of welded joints was fairly inferior to that of the base metal, but far higher than the IIW recommended value. Furthermore, welding defects were well believed to contribute to the shorter fatigue life. The small fatigue crack growth presented highly discontinuous and inhomogeneous due to microstructure and porosity. By contrast, the crack stable growth stage was less sensitive to microstructural features of hybrid welded joints.

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On the fatigue performance of laser hybrid welded high Zn 7000 alloys for next generation railway components

Cited by 75 publications

References 35 publications

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Fatigue behaviors of laser hybrid welded AA7020 due to defects via synchrotron X‐ray microtomography

Effect of filler metal feed rate and composition on microstructure and mechanical properties of fibre laser welded AA 2024-T3

Effect of microstructural features on the failure behavior of hybrid laser welded AA7020

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