한국산학기술학회논문지 (Journal of the Korea Academia-Industrial cooperation Society)

  • 제17권10호
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  • Pages.280-288
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  • 2016
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  • 1975-4701(pISSN)
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  • 2288-4688(eISSN)
한국산학기술학회 (The Korea Academia-Industrial cooperation Society)
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마찰교반용접 툴 변화에 따른 마그네슘 합금 압출 판재 마찰교반용접부 기계적 물성 평가

Evaluation of Mechanical Properties of Extruded Magnesium Alloy Joints by Friction Stir Welding : Effect of Welding Tool Geometry

  • 선승주 (과학기술연합대학원대학교 철도시스템공학과) ;
  • 김정석 (한국철도기술연구원) ;
  • 이우근 (과학기술연합대학원대학교 철도시스템공학과) ;
  • 임재용 (대구대학교 기계공학부)
  • Sun, Seung-Ju (Dept. of Railway System Engineering, University of Science and Technology) ;
  • Kim, Jung-Seok (Advanced Materials Research Team, Korea Railroad Research Institute) ;
  • Lee, Woo-Geun (Dept. of Railway System Engineering, University of Science and Technology) ;
  • Lim, Jae-Yong (School of Mechanical Engineering, Daegu University)
  • 투고 : 2016.09.07
  • 심사 : 2016.10.07
  • 발행 : 2016.10.31
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초록

본 연구의 목적은 마찰교반용접을 마그네슘 합금에 응용하기에 앞서 형상이 다른 두 종류의 용접 툴을 마찰교반용접 시험에 적용 및 비교하여 마그네슘 합금 마찰교반용접에 더 적합한 용접 툴을 제안하였다. 용접 툴의 효과를 알아보기 위해서 용접조건 변수 중 이송속도는 200mm/min으로 고정하였고 회전속도를 400, 600, 800rpm으로 변화시키면서 용접부의 거동과 용접 툴 변화에 따른 효과를 평가 및 관찰하였다. 기계적 물성 평가를 위해 인장시험과 경도시험을 수행하였으며, 용접부 내 거동 및 결함의 유무를 확인하기 위하여 용접부에 수직인 방향의 횡단면을 광학현미경을 통해 관찰하였다. 용접 툴에 관계없이 회전속도가 400rpm일 때 결함이 관찰되었으며, 회전속도가 증가할수록 결함이 감소하는 경향을 보였다. 최종적으로 회전속도 800rpm에서 결함이 없는 용접부를 얻었다. 용접 툴 변화에 따른 기계적 물성 평가 결과 C type 용접 툴을 적용한 경우 보다 우수한 결과가 나타났다. 기계적 물성이 가장 우수한 용접조건은 회전속도 800rpm, 이송속도 200mm/min 이었고, 이때 용접부의 인장강도, 항복강도 그리고 연신율은 모재 대비 90.0%, 69.1%, 83.2% 수준으로 각각 나타났다.

This study proposes improved welding tools for magnesium alloys. Two types of tools were used for friction stir welding (FSW). The effect of the welding tools on the FSW joints was investigated with a fixed welding speed of 200mm/min and various rotation speeds of 400 to 800 rpm. After FSW, the joints were cross-sectioned perpendicular to the welding direction to investigate the defects. A tensile test and Vickers hardness test were conducted to identity the mechanical properties of the joints. Defects were observed when the rotation speed was 400 rpm, regardless of the welding tool, and the amount of defects tended to decrease with increases in rotational speed. Defect-free welds were obtained when the rotation speed was 800 rpm. The best weld quality was acquired using the C type welding tool. The rotation speed of 800 rpm and welding speed of 200 mm/min produced the best joining properties. The ultimate tensile strength, yield strength, and elongation of the welded region were 90.0%, 69.1%, and 83.2% those of the base metal, respectively.

키워드

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