• 제목/요약/키워드: Fine Recrystallized Zone

검색결과 12건 처리시간 0.021초

2024 알루미늄의 마찰용접에 관한 연구 (A study on friction welding of 2024 aluminium)

  • 송오성;강춘식
    • Journal of Welding and Joining
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    • 제8권3호
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    • pp.24-30
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    • 1990
  • 2024 Aluminium was welded by domestic manufactured continuous type friction welder. The problems and optimum condition were studied in 2024 Al-2024 Al cases. Mechanical tests and microstructure analysis were studeid. Interfacial temperature of welding was predicted by FDM. The obtained results are as follows: 1) In case of Al-Al, the optimum condition range was wide. 2) At the boundary zone, fine recrystallized zone was not harmful to the mechanical property and no growth of precipitation was observed. 3) In case of Al-Al, temperature gradient can be predictedby FDM and heat input can be taken as weld parameter.

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

  • Lee, Won-Bae;Yeon, Yun-Mo;Jung, Seung-Boo
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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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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마찰교반용접한 AZ31B-H24 마그네슘 합금의 용접특성에 미치는 용접조건의 영향 (The Effects of Welding Conditions on the Joint Properties of the Friction Stir Welded AZ31B-H24 Mg Alloys)

  • 이원배;방극생;연윤모;정승부
    • Journal of Welding and Joining
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    • 제20권5호
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    • pp.87-92
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    • 2002
  • Weldability of Friction Stir Welded(FSW) AZ31B-H24 Mg alloy sheet with 4m thick was evaluated by changing welding speed. The sound welding conditions mainly depended on the suffiicient welding heat input during the process. The insufficient heat input resulted in the void like defect in the weld zone. Higher welding speed caused a larger inner void or lack of bonding. The defects were distributed at the stir zone or the transition region between stir zone and thermo-mechanical affected zone (UE). The size of defects slightly increased with increasing welding speed. These defects had a great effect on the joint strength of weld zone. The weld zone was composed of stir zone, TMAZ and heat affected zone. The stir zone was cosisted of fine recrystallized structure with $5-8\mu\textrm{m}$ in the mean grain size. The hardness of weld zone was near the 60HV, which was slightly lower than that of base metal. The maximum joint strength was about 219MPa that was 75% of that of base metal and the yield strength was also lower than that of base metal partly due to the existance of defects.

Mg 합금의 제조 방법에 의한 FSW 접합성 평가 (The Evaluation of Weldability for Different Manufactured Mg Alloys in FSW)

  • 노중석;김홍주;장웅성;방국수
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2003년도 추계학술발표대회 개요집
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    • pp.256-258
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    • 2003
  • Hot-rolled and Extruded plates of AZ type magnesium alloys were successfully joined by friction stir welding(FSW). AZ31B-H24 and AZ61 plates with the thickness of 4mm were used, and the microstructural development in the stir zone were investigated using optical and scanning electron microscopes. The grain size of base metal and stir zone were investigated using the line-intersecter method. Hardness of the stir zone was remarkably increased due to very fine recrystallized grain structure both in AZ3l and AZ6l alloys. Tensile strengths of the FS welded Mg alloys AZ31 and AZ61 were strongly affected by formation of the intermetallic compounds, ${\beta}$-Al$\sub$12/Mg$\sub$17/.

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THE JOINT CHARACTERISTICS OF FRICTION STIR WELDED AZ91D MAGNESIUM ALLOYS

  • Kim, Jong-Woong;Lee, Won-Bae;Yeon, Yun-Mo;Jung, Seung-Boo
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.516-521
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    • 2002
  • A study was carried out to grow an understanding of the microstructural development of friction stir welds on an AZ91D magnesium alloy, and to evaluate the mechanical properties of the welds. AZ91D plates with the thickness of 4mm were used, and the microstructural development of the weld zone was investigated using optical and scanning electron microscopes. Square butt welding joint with good quality was obtained at the conditions of under 187mm/min of travel speed with 1100 to 1250 rpm of tool rotation speed. The microstructure within the weld region consisted of fine equiaxed grains with no evidence of the original dendritic structure. The hardness tests showed slightly increased harness in the weld region, and the minimum hardness measured is in that of the parent material. Tensile strength of the weld zone was remarkably improved due to very fine recrystallized structure. XRD pattern of weld zone revealed the removal of $\beta$ intermetallic compounds, $Mg_{17}$Al$_{12}$, which had been distributed in the base metal.l.

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5052 알루미늄 합금 마찰교반접합부 특성에 미치는 접합인자의 영향 (Effect of Welding Parameters on the Friction Stir Weldability of 5052 Al alloy)

  • 이원배;김상원;이창용;연윤모;장웅성;서창제;정승부
    • Journal of Welding and Joining
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    • 제22권3호
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    • pp.69-76
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    • 2004
  • Effects of friction stir welding parameters such as tool rotation speed and welding speed on the joints properties of 5052 Al alloys were studied in this study. A wide range of friction stir welding conditions could be applied to join 5052 AA alloy without defects in the weld zone except for certain welding conditions with a lower heat input. Microstructures near the weld zone showed general weld structures such as stir zone (SZ), thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). Each zone showed the dynamically recrystallized grain, transient grain and structure similar to base metal's, respectively. Hardness distribution near the weld zone represented a similar value of the base metal under wide welding conditions. However, in case of 800 rpm of tool rotation speed, hardness of the stir zone had a higher value due to the fine grain with lots of dislocation tangle, a higher angle grain boundary and some of Al3Fe particles. Except joints with weld defects, tensile strength and elongation of the joints had values similar to the base metal values and fracture always occurred in the regions approximately 5mm away from the weld center.

마찰교반접합한 오스테나이트계 스테인리스강과 6013알루미늄 합금 이종 접합부의 접합 특성 및 계면 성질 (Joint properties and Interface Analysis of Friction Stir Welded Dissimilar Materials between Austenite Stainless Steel and 6013 Al Alloy)

  • 이원배;;;정승부
    • Journal of Welding and Joining
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    • 제23권5호
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    • pp.61-68
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    • 2005
  • Dissimilar joining of Al 6013-T4 alloys and austenite stainless steel was carried out using friction stir welding technique. Microstructures near the weld zone and mechanical properties of the joint have been investigated. Microstructures in the stainless steel side were composed of the heat affected zone and the plastically deformed zone, while those in the Al alloy side were composed of the recrystallized zone including stainless steel particles, the thermo-mechanically affected zone and the heat affected zone. TEM micrographs revealed that the interface region was composed of the mixed layers of elongated stainless steel and ultra-fine grained Al alloy with lamella structure and intermetallic compound layer. Thickness of the intermetallic layer was approximately 300nm and was identified as the A14Fe with hexagonal close packed structure. Mechanical properties, such as tensile and fatigue strengths were lower than those of 6013 Al alloy base metal, because tool inserting location was deviated to Al alloy from the butt line, which resulted in the lack of the stirring.

FRICTION STIR WELDING OF MAGNESIUM ALLOYS

  • Kazuhiro Nakata;Kim, Young-Gon;Masao Ushio
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.511-515
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    • 2002
  • Extruded and cast plates of AZ type magnesium alloys were successfully joined by friction stir welding (FSW). Effect of FSW conditions on the formation of the defect was revealed in relation to tool rotation speed and specimen travel speed. Magnesium alloy with higher aluminum content became difficult to be joined and the optimum condition without defect was restricted into narrow condition range. The structure of the stirred zone was a fine-grained recrystallized structure even in the case of cast AZ91D. FSW joint had better mechanical properties than those of GTA welded joint. Especially the toughness of the stirred zone increased more than that of the base metal.

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저항 업셋 용접방식에 따른 Zircaloy-4 핵연료 피복재 용접부의 미세조직 특성 (Microstructural Characteristics of Zircaloy-4 Nuclear Fuel Cladding Welds by Resistance Upset Welding Processes)

  • 고진현;김상호;박춘호;김수성
    • Journal of Welding and Joining
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    • 제20권3호
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    • pp.98-104
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    • 2002
  • A study on microstructures of welds for Zircaloy-4 sheath end closure by the resistance upset welding methods was carried out. Two upset welding process variations such as magnetic farce and multi-impulse resistance welding were used. Grain size and microhardness across welds were analysed in terms of welding parameters. Magnetic farce resistance weld with one cycle of unbalanced mode has smaller upset length and $\alpha-grain$ size in heat affected zone than those of multi-impulse resistance weld because of lower heat input and shorter welding time. Heat affected zone formed by two upset resistance welding variations revealed fine Widmanstatten structure or martensitic ${\alpha}'$ structure due to the high heating rate and foster cooling rate. Magnetic force resistance welds showed recrystallized grains before grain growth, whereas multi-impulse resistance welds showed full grain growth.

전신 및 주조된 Mg합금의 FSW 접합성 평가 (Evaluation of FSW Weldability of Wrought and Casting Mg Alloys)

  • 노중석;김흥주;장웅성;방국수
    • Journal of Welding and Joining
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    • 제22권5호
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    • pp.53-57
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    • 2004
  • Friction stir weldability of AZ31B-H24, AZ61A-F and AZ91C-F Mg alloys were studied using microstructural observation and mechanical tests. The microstructure of stir zone(SZ) was coarse in AZ31B-H24 alloy whereas it was very fine both in AZ61A-F and AZ91C-F alloys. The hardness of SZ was remarkably increased by very fine recrystallized grains both in AZ61A-F and AZ91C-F alloys. On the other hand, the hardness of SZ was decreased in AZ31B-H24 due to the coarse microstructure. In SZ, AZ91C-F alloy showed very high hardness values because of dispersion hardening of $Mg_{17}$Al$_{12}$($\beta$ phase) and Al solid solution hardening. Because of more $Mg_{ 17}Al_{12}($\beta$ phase)$ intermetallic compounds, Mg alloy with high Al content showed poor mechanical properties.s.