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Microstructures of Friction Stir Lap Weld in A5052-H112 Alloy

A5052-H112 합금의 겹치기 마찰교반접합 조직 특성

  • Ko, Young-Bong (Dept. of Testing and Research Team, Korea Testing & Research Institute) ;
  • Lee, Joong-Hun (Dept. of technical research center, Hyundai-steel company) ;
  • Park, Kyeung-Chae (Dept. of Materials Sciences and Metallurgy, Kyungpook National University)
  • 고영봉 (한국화학시험연구원 시험연구팀) ;
  • 이중헌 (현대제철 기술연구소) ;
  • 박경채 (경북대학교 금속신소재공학과)
  • Published : 2009.12.31

Abstract

The Friction Stir Welding(FSW) has mainly been used for making butt joints in Al alloys. Development of Friction Stir Lap Welding(FSLW) would expand the number of applications. Microstructure of FSLW in A5052-H112 alloy was investigated under varying rotation and welding speed. As the rotation speed was increased and the welding speed was decreased, a amount of heat was increased. As a result, bead interval was narrower, bead width are larger, and experimental bead interval was almost similar to theoretical bead interval. Typical microstructures of FSLW A5052-H112 alloy consist of three zones, including Stir Zone(SZ), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). As a amount of heat was increased, average grain size was larger in three zones. Nevertheless, the aspect ratio was almost fixed for FSLW conditions. The misorientation of SZ, HAZ and TMAZ was examined. A large number of low angle grain boundaries, which were formed by severe plastic deformation, were showed in TMAZ as comparison with SZ and HAZ. Microhardness distribution was high in order of BM, SZ, TMAZ, and HAZ. The Micro-hardness distribution in HAZ, TMAZ of upper plate were lager than lower plate. Relationship between average grain size and microhardness was almost corresponded to Hall-Petch equation.

Keywords

References

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