• Title, Summary, Keyword: Friction Stir Welding

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Effects of Welding Condition on Hardness and Microstructure of Friction Stir Welded Joints of AI-7075-T651 Plate (용접조건이 AI-7075-T651의 마찰교반용접부의 경도와 미세조직에 미치는 영향)

  • Kim, C.O.;Sohn, H.J.;Kim, S.J.
    • Journal of Power System Engineering
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    • v.15 no.3
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    • pp.58-64
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    • 2011
  • As well known, the friction stir welding is a novel welding process which is a solid state welding process for sheet or plate using the friction stir phenomenon. This paper describes the effect of welding condition such as the rotation speed and the travelling speed during the friction stir welding process on the micro Virkers hardness and the microstructure of friction stir welded joints in AI-7075-T651 plate. From those investigations, the highest hardness of stir zone was observed at the welding condition of SO-3. The microstructures of the friction stir welded joints was not dependent on the welding conditions, but in the SO-4 specimen, the friction stir welding defect like tunnel shape was found in stir zone.

Electric Resistance Heated Friction Stir Spot Welding of Overlapped Al5052 Alloy Sheets (중첩된 알루미늄 5052 합금판재의 전기저항가열 마찰교반점용접에 관한 연구)

  • Kim, T.H.;Jang, M.S.;Jin, I.T.
    • Transactions of Materials Processing
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    • v.24 no.4
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    • pp.256-263
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    • 2015
  • Electric resistance spot welding has been used to join overlapped steel sheets in automotive bodies. Recently to reduce weight in automotive vehicles, non-ferrous metals are being used or considered in car bodies for hoods, trunk lids, doors parts, etc. Various welding processes such as laser welding, self-piercing rivet, friction stir welding are being used. In the current study, a new electric resistance heated friction stir spot welding is suggested for the spot welding of non-ferrous metals. The welding method can be characterized by three uses of heat -- electric resistance heating, friction stir heating and conduction heating of steel electrodes -- for the fusion joining at the interfacial zone between the two sheets. The welding process has variables such as welding current, diameter of the steel electrodes, revolutions per minute (rpm) of the friction stir pin, and the insert depth of the stir pin. In order to obtain the optimal welding variables, which provide the best welding strength, many experiments were conducted. From the experiments, it was found that the welding strength could be reached to the required production value by using an electrode diameter of 10mm, a current of 7.6kA, a stirring speed of 400rpm, and an insert depth of 0.8mm for the electric resistance heated friction stir spot welding of 5052 aluminum 1.5mm sheets.

THE EVALUATION OF MICROSTRUCTURE AND MECHANICAL PROPERTIES OF FRICTION STIR WELDEDAL-MG-SI ALLOY

  • Lee, Won-Bae;Yeon, Yun-Mo;Jung, Seung-Boo
    • Proceedings of the KWS Conference
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    • pp.499-504
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    • 2002
  • The microstructural change associated with the hardness profile in friction stir welded, age-hardenable 6005 Al alloy had been evaluated. Frictional heat and plastic flow during friction stir welding created the fine recrystallized grain (Stir Zone, SZ), the elongated and recovered grain (Thermo-Mechanical Affected Zone, TMAZ) in the weld zone. Heat affected zone (HAZ), which could be only identified by hardness test because there is no difference in the grain structure compared with that of the base metal, was formed beside the weld zone. A softened region had been formed near the weld zone during friction stir welding process. The softened region was characterized by the dissolution and coarsening of the strengthening precipitate during the friction stir welding. The sound joints of 6005 Al alloys were successfully formed under a wide range of the friction stir welding conditions.

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Development of Microstructure and Mechanical Properties of Friction Stir Lap Jointed Invar 42/SS 400 (겹치기 마찰교반접합된 Invar 42/SS 400 합금의 미세조직과 기계적 특성 발달)

  • Song, K.H.;Nakata, Kazuhiro
    • Journal of Welding and Joining
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    • v.30 no.5
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    • pp.34-39
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    • 2012
  • This study was conducted to investigate the microstructure and mechanical properties of friction stir lap joints. Invar 42 and SS 400 were selected as the experimental materials, and friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. The application of friction stir welding to Invar 42 effectively reduced the grain size in the stir zone; the average grain size of Invar 42 was reduced from $11.5{\mu}m$ in the base material to $6.4{\mu}m$ in the stir zone, which resulted in an improvement in the mechanical properties of the stir zone. The joint interface between Invar 42 and SS 400 showed a relatively sound weld without voids and cracks, and the intermetallic compounds with $L1_2$ type in lap jointed interface were partially formed with size of 100 nm. Moreover, the hook in the advancing side of Invar 42 was formed from SS 400, which contributed to maintenance of the tensile strength. The evolution of microstructures and mechanical properties of friction stir lap jointed Invar 42 and SS 400 are also discussed herein.

Friction stir welding with back-bead to improve fatigue strength (이면비드를 가진 마찰교반용접에 대한 피로강도에 관한 연구)

  • Rajesh, S.R.;Yun, Byeong-Hyeon;Kim, Heung-Ju;Kim, Teuk-Gi;Cheon, Chang-Geun;Jang, Ung-Seong
    • Proceedings of the KWS Conference
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    • pp.17-19
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    • 2007
  • The fatigue experiments of friction stir welded Al-6061-T6 alloy with and with out back bead were performed to investigate the variation in fatigue strength and life of the Joint. It was found that there were always existed flaws at the roots of friction stir welds for the normal welding parameters and clamping conditions. In order to overcome this root flaws, friction stir welds with optimum back bead has been developed. The test results with root flaws and with back bead were compared. The fatigue life of weld with root flaws was 5-10 times shorter than that of the friction stir weld with back bead.

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A Development of Optimizing Tools for Friction Stir Welding with 2 mm Thick Aluminum Alloy using a Milling Machine (밀링을 이용한 AI합금의 마찰 교반용접용 최적공구형상 및 치수개발에 관한 연구)

  • 장석기;신상현
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.4
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    • pp.791-796
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    • 2001
  • Friction stir welding is a solid phase welding process that does not melt the metal when welding. The FSW is the most remarkable and potentially useful new welding technique that is still in development. Friction stir butt welding process on 2 mm thick Al 1050 plates by utilizing a milling machine was experimentally studied. With the optimized heat generating tool welds could be achieved that are void and crack free. It was found that the friction stir welded tensile test specimens failed in the HAZ outside of the weld metal, and that the tensile strength was above 90% of that of the base metal.

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Friction Stir Welding of Aluminium alloys and Its Application (알루미늄합금의 마찰교반접합 및 그 적용)

  • 연윤모;정승부;박종목
    • Proceedings of the KSR Conference
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    • pp.226-234
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    • 2000
  • The friction stir welding technique is a derivative of conventional friction welding, which enables the advantages of solid-phase welding to be applied to the fabrication of long butt and lap joints, with very little postweld distortion. Friction stir welding is a remarkable new welding technique for joining aluminum alloys and has the potential for welding other ferrous materials. It has already been developed beyond a laboratory curiosity and has been proved as a potential practical welding technique offering low-distortion, high-quality, low-cost welds from simple concept machine tool welding equipment. To bring this remarkable method of welding aluminum alloys to the attention of Industry, this article introduces the basic principle of friction stir welding, pointing out the practical advantages and most important of all, describes the exceptionally good metallurgical and mechanical properties.

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Evaluation of Microstructure and Mechanical Properties of Friction Stir Lap Jointed Inconel 600/SS 400 (겹치기 마찰교반접합된 Inconel 600/SS 400 합금의 미세조직과 기계적 특성 평가)

  • Song, Kuk-Hyun;Nakata, Kazuhiro
    • Korean Journal of Materials Research
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    • v.22 no.3
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    • pp.123-129
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    • 2012
  • The microstructures and mechanical properties of friction stir welded lap joints of Inconel 600 and SS 400 were evaluated; friction stir welding was carried out at a tool rotation speed of 200 rpm and welding speed of 100 mm/min. Electron back-scattering diffraction and transmission electron microscopy were introduced to analyze the grain boundary characteristics and the precipitates, respectively. Application of friction stir welding was notably effective at reducing the grain size of the stir zone. As a result, the reduced average grain size of Inconel 600 ranged from $20{\mu}m$ in the base material to $8.5{\mu}m$ in the stir zone. The joint interface between Inconel 600 and SS 400 showed a sound weld without voids and cracks, and MC carbides with a size of around 50 nm were partially formed at the Inconel 600 area of lap joint interface. However, the intermetallic compounds that lead to mechanical property degradation of the welds were not formed at the joint interface. Also, a hook, along the Inconel 600 alloy from SS 400, was formed at the advancing side, which directly brought about an increase in the peel strength. In this study, we systematically discussed the evolution of microstructures and mechanical properties of the friction stir lap joint between Inconel 600 and SS 400.

Mechanical Properties of Friction Stir Welded Ni-Base Superalloy (마찰교반접합된 니켈기 초합금의 기계적 특성)

  • Song, Kuk-Hyun;Nakata, Kazuhiro
    • Korean Journal of Materials Research
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    • v.21 no.7
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    • pp.410-414
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    • 2011
  • This study was carried out to evaluate the microstructures and mechanical properties of a friction stir welded Ni based alloy. Inconel 600 (single phase type) alloy was selected as an experimental material. For this material, friction stir welding (FSW) was performed at a constant tool rotation speed of 400 rpm and a welding speed of 150~200 mm/min by a FSW machine, and argon shielding gas was utilized to prevent surface oxidation of the weld material. At all conditions, sound friction stir welds without any weld defects were obtained. The electron back-scattered diffraction (EBSD) method was used to analyze the grain boundary character distributions (GBCDs) of the welds. As a result, dynamic recrystallization was observed at all conditions. In addition, grain refinement was achieved in the stir zone, gradually accelerating from 19 ${\mu}m$ in average grain size of the base material to 5.5 ${\mu}m$ (150 mm/min) and 4.1 ${\mu}m$ (200 mm/min) in the stir zone with increasing welding speed. Grain refinement also led to enhancement of the mechanical properties: the 200 mm/min friction stir welded zone showed 25% higher microhardness and 15% higher tensile strength relative to the base material.

Mechanical properties of friction stir welded aluminum alloys 5083 and 5383

  • Paik, Jeom-Kee
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.1 no.1
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    • pp.39-49
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    • 2009
  • The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW), laser welding and friction stir welding (FSW), FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base) alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009), jointly funded by its member agencies.