On the forming mechanism of banded structures in aluminium alloy friction stir welds

Chen, Z.W.; Chen, Song

doi:10.1016/j.scriptamat.2007.10.026

Cited by 84 publications

(35 citation statements)

References 18 publications

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“…The features of the nugget in the present sample are different to the commonly observed onion ring structure in FS nugget. This means that the out flow from thread spaces forming the nugget zone in the present case differs from those identified for the case of forming onion rings [17]. Non-ring nugget structure is, however, not uncommon and can be identified in FS nuggets presented in literature for FSW/P of similar cast alloys [18][19][20][21].…”

Section: Methodscontrasting

confidence: 49%

Effects of Rotation Speed and Forward Speed on Stir Zone Formation During Friction Stir Processing of Al-7Si-0.3Mg Alloy

Cui¹,

Chen²

2010

Int.J.Soc.Mater.Eng.Resour.

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Friction stir processing (FSP) could potentially be used to modify and refine the microstructures of aluminium alloy castings for use as structural rather than non-structural components. However, there is currently an insufficient understanding on how FSP parameters affect the individual and combined flows forming the various regions in the processed zone during FSP in literature. In this study, a cast Al-7Si-0.3Mg alloy was used to provide readily identifiable processed zones. A series of FS experiments covering a wide range of tool forward (v) and rotation ( ω ) speeds were conducted followed by the measurement of individual and combined stir zone areas. We have identified that the deformation of α (Al) dendrites and eutectic AlSi sheared by the pin resulting in fine Si particles evenly distributed in α (Al) matrix was a major mode of flow. Another mode of flow was associated with the material merely dragged into the FS zone and, as a result, Si-particle clusters remained. The basic modes of material flow did not change but the volume of each individual flow and combined flow volume depended on both v and ω . The trends observed on the present data can explain how pin rotation relates to the material transportation mechanism and the associated torque (M) required. The present data also explains how v, not ω , relates to specific energy (E s ) and the volume of the total stir zone.

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Section: Methodscontrasting

confidence: 49%

Effects of Rotation Speed and Forward Speed on Stir Zone Formation During Friction Stir Processing of Al-7Si-0.3Mg Alloy

Cui¹,

Chen²

2010

Int.J.Soc.Mater.Eng.Resour.

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“…Compared with BMs, the SZ contains more elongated and finer austenitic islands. Similar to the typical microstructure of Al alloy and steel joints welded through FSW [16,17,[24][25][26][27], the average grain size is significantly finer in the SZ than in the BM because the SZ experiences higher temperature and has undergone significantly plastic deformation. No significantly grain coarsening and σ phase are observed across the welded joint.…”

Section: Materials and Experimentsmentioning

confidence: 71%

“…In addition, FSW prevents precipitation. Initially, FSW is mainly used in metals with low-melting points, such as Al and Mg alloys, because the tools used in FSW display limited capacities at high temperatures [16,17]. With the improvement in tools used in FSW, the application of FSW is extended to materials with high melting points, such as steel and titanium alloys.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Microstructure, Mechanical Properties, and Corrosion Resistance of a Friction-Stir-Welded Joint of Hyper Duplex Stainless Steel

Xing-long

et al. 2017

Metals

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This study investigates the microstructure, mechanical properties, and corrosion resistance of a friction-stir-welded joint of the hyper duplex stainless steel SAF2707. Friction stir welding (FSW) is performed at a tool rotation rate of 400 rpm and a welding speed of 100 mm/min. The microstructure of the joints is examined using scanning electron microscopy and X-ray diffraction. Tensile test and fractography are subsequently employed to evaluate the mechanical properties of the joints. Results show that the grain size of the stir zone (SZ) is smaller than that of the base metal (BM). Electron back-scattered diffraction analysis reveals that fine-equiaxed grains form in the SZ because of the dynamic recrystallization during the FSW. These grains become increasingly pronounced in the austenite phase. The tensile specimens consistently fail in the BM, implying that the welded joint is an overmatch to the BM. Moreover, the welded joints consist of finer grains and thus display higher tensile strength than their BMs. Potentiodynamic polarization curves and impedance spectroscopy both demonstrate that the corrosion resistance of the SZ is superior to that of the base material.

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“…6f. The distinctive appearance of the AS and RS interface was explained by the deposition of material layers behind the tool as a function of traverse per revolution [15][16][17][18][19][20]. In the first half of the revolution of the tool the material transmits from AS and accumulates at RS.…”

Section: Optical Microstructurementioning

confidence: 99%

Microstructure examination and microhardness of friction stir welded joint of (AA7020-O) after PWHT

et al. 2018

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This paper studies the microstructure and microhardness of the welded joints of the annealed aluminum alloy AA7020-O produced by friction stir welding (FSW) technique. The material was applied to post weld heat treatment (solution treatment and artificially aged, T6). The traverse speed and the rotational speed are the most important process parameters of FSW, and have great influence on the heat input of the welding operation which governs the welded joints quality. To investigate their effect, the welding operation was performed using three traverse speeds, 20, 40 and 60 mm/s with two rotational speeds of 1125 and 1400 rpm, and other welding parameters were kept constant to produce comparable joints. It was found that the two rotational speeds are accepted with lower traverse speeds to produce sound joints. Microstructure of the welded joints was significantly affected by the FSW process parameters, and slight effect was reported for the grain size. Microhardness examination showed high weld joint quality with respect to the base metal hardness, which proves the reprecipitation of the hardening phase in the weld zone. The microhardness profile was strongly dependant on the rotational speed, and the average values of the joints hardness have increased with the decrease in the rotational speed, where it have been slightly affected by the welding speed. ª 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of Housing and Building National Research Center. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

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On the forming mechanism of banded structures in aluminium alloy friction stir welds

Cited by 84 publications

References 18 publications

Effects of Rotation Speed and Forward Speed on Stir Zone Formation During Friction Stir Processing of Al-7Si-0.3Mg Alloy

Effects of Rotation Speed and Forward Speed on Stir Zone Formation During Friction Stir Processing of Al-7Si-0.3Mg Alloy

Characterization of the Microstructure, Mechanical Properties, and Corrosion Resistance of a Friction-Stir-Welded Joint of Hyper Duplex Stainless Steel

Microstructure examination and microhardness of friction stir welded joint of (AA7020-O) after PWHT

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