Investigation of weld defects in friction-stir welding and fusion welding of aluminium alloys

Kah, Paul; Rajan, Richard; Martikainen, Jukka; Suoranta, Raimo

doi:10.1186/s40712-015-0053-8

Cited by 163 publications

(84 citation statements)

References 37 publications

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“…Slag inclusions in fusion welding likewise cause local interruptions in the microstructure [40,45]. These defects are distinguishable inside the weld region underneath the surface and can be identified by micro-cracks and streak-like segregation, with gas blisters in their immediate proximity [43][44][45]. As a result, these defects can be harmful for the structural integrity and may decrease the strength characteristics of the weld.…”

Section: Coherent Interfacesmentioning

confidence: 99%

“…Sometimes the crushed particles from breaking of the oxide surface layer cannot escape from the shoulder's rotation and are sucked into the stirring region. Slag inclusions in fusion welding likewise cause local interruptions in the microstructure [40,45]. These defects are distinguishable inside the weld region underneath the surface and can be identified by micro-cracks and streak-like segregation, with gas blisters in their immediate proximity [43][44][45].…”

Section: Coherent Interfacesmentioning

confidence: 99%

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Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds

Tamadon

Pons

Sued

et al. 2017

Metals

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BACKGROUND-The solid-phase joining of A6082-T6 plates by bobbin friction stir welding (BFSW) is problematic. Better methods are needed to evaluate the microstructural evolution of the weld. However, conventional Al reagents (e.g., Keller's and Kroll's) do not elucidate the microstructure satisfactorily, specifically regarding grain size and morphology within the weld region. APPROACH-We developed innovative etchants for metallographic observations for optical microscopy. RESULTS-The macrostructure and microstructure of A6082-T6 BFSW welds were clearly demonstrated by optical microscopy analysis. The microetching results demonstrated different microstructures of the Stir Zone (S.Z) distinct from the Base Metal (B.M) and Heat Affected Zone (HAZ) & Thermo-mechanical Affected Zone (TMAZ). The micrographs showed a significant decrease in grain size from 100 µm in B.M to ultrafine 4-10 µm grains for the S.Z. Also, the grain morphology changed from directional columnar in the B.M to equiaxed in the S.Z. Furthermore, thermomechanical recrystallization was observed by the morphological flow of the grain distortion in HAZ and TMAZ. The etchants also clearly show the polycrystalline structure, microflow patterns, and the incoherent interface around inclusion defects. ORIGINALITY-Chemical compositions are identified for a suite of etchant reagents for metallographic examination of the friction-stir welded A6082-T6 alloy. The reagents have made it possible to reveal microstructures not previously evident with optical microscopy.

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Section: Coherent Interfacesmentioning

confidence: 99%

Section: Coherent Interfacesmentioning

confidence: 99%

Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds

Tamadon

Pons

Sued

et al. 2017

Metals

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“…The major difference between ns-LAAPTOF and fs-LAAPTOF spectra is the absence of gold peaks in the fs spectra. At the wavelength of the excimer ns laser (193 nm), the reflectance of both gold and silver are nearly 35 % (Kah et al, 2015). At the wavelength of the fs laser (800 nm), the reflectance is more than 95 % for both gold and silver.…”

Section: Sio 2 Particlesmentioning

confidence: 92%

Exploring femtosecond laser ablation in single-particle aerosol mass spectrometry

et al. 2018

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Abstract. Size, composition, and mixing state of individual aerosol particles can be analysed in real time using singleparticle mass spectrometry (SPMS). In SPMS, laser ablation is the most widely used method for desorption and ionization of particle components, often realizing both in one single step. Excimer lasers are well suited for this task due to their relatively high power density (10 7 -10 10 W cm −2 ) in nanosecond (ns) pulses at ultraviolet (UV) wavelengths and short triggering times. However, varying particle optical properties and matrix effects make a quantitative interpretation of this analytical approach challenging. In atmospheric SPMS applications, this influences both the mass fraction of an individual particle that is ablated, as well as the resulting mass spectral fragmentation pattern of the ablated material. The present study explores the use of shorter (femtosecond, fs) laser pulses for atmospheric SPMS. Its objective is to assess whether the higher laser power density of the fs laser leads to a more complete ionization of the entire particle and higher ion signal and thus improvement in the quantitative abilities of SPMS. We systematically investigate the influence of power density and pulse duration on airborne particle (polystyrene latex, SiO 2 , NH 4 NO 3 , NaCl, and custom-made core-shell particles) ablation and reproducibility of mass spectral signatures. We used a laser ablation aerosol time-of-flight single-particle mass spectrometer (LAAPTOF, AeroMegt GmbH), originally equipped with an excimer laser (wavelength 193 nm, pulse width 8 ns, pulse energy 4 mJ), and coupled it to an fs laser (Spectra Physics Solstice-100F ultrafast laser) with similar pulse energy but longer wavelengths (266 nm with 100 fs and 0.2 mJ, 800 nm with 100 fs and 3.2 mJ). We successfully coupled the freefiring fs laser with the single-particle mass spectrometer employing the fs laser light scattered by the particle to trigger mass spectra acquisition. Generally, mass spectra exhibit an increase in ion intensities (factor 1 to 5) with increasing laser power density (∼ 10 9 to ∼ 10 13 W cm −2 ) from ns to fs laser. At the same time, fs-laser ablation produces spectra with larger ion fragments and ion clusters as well as clusters with oxygen, which does not render spectra interpretation more simple compared to ns-laser ablation. The idea that the higher power density of the fs laser leads to a more complete particle ablation and ionization could not be substantiated in this study. Quantification of ablated material remains difficult due to incomplete ionization of the particle. Furthermore, the fslaser application still suffers from limitations in triggering it in a useful time frame. Further studies are needed to test potential advantages of fs-over ns-laser ablation in SPMS.

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“…The FSW only used the single sided shoulder rotating tool and the weld form on one side of the material [2]. The material is softened by heat generation of the tool action that rotated and transverse and later resulting the severe material deformation [3]. The plasticized material is flowed from the tool's front to the edge of the trailing and form the weld joint [4].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Bobbin Friction Stir Welded 1100 Aluminum Alloys using Response Surface Methodology

Nasir¹,

Sued²,

Abidin³

2019

IJRTE

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This paper presents the modelling of the mechanical properties of the bobbin friction stir welded of 6 mm thick AA1100 with control factors of spindle and welding speeds. Face-centered composite design (FCCD) was used to design the experimental work and the results of the responses and the combination of factors were analyzing through analysis of variance (ANOVA). From ANOVA, the result indicates that both spindle and welding speed influence significantly the tensile strength and average hardness at SZ of AA1100. The optimum factors for maximum tensile strength and average hardness of the AA1100 were 950 rpm and welding speed of 130 mm/min. Both models giving a relative small percentage error of 0.8 % and 1.64 % for tensile strength model and average hardness in stir zone (SZ) region, respectively, thus indicate the models were adequate.

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Investigation of weld defects in friction-stir welding and fusion welding of aluminium alloys

Cited by 163 publications

References 37 publications

Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds

Development of Metallographic Etchants for the Microstructure Evolution of A6082-T6 BFSW Welds

Exploring femtosecond laser ablation in single-particle aerosol mass spectrometry

Optimization of Bobbin Friction Stir Welded 1100 Aluminum Alloys using Response Surface Methodology

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