Journal of the Korean Society for Railway (한국철도학회논문집)

The Korean Society for Railway (한국철도학회)
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Evaluation of Mechanical Properties and Analysis of Microstructure of AZ61 Magnesium Alloy Butt Joints by Friction Stir Welding

AZ61 마그네슘 합금 마찰교반용접부의 기계적 특성 평가 및 미세조직 분석

  • Sun, Seung-Ju (Department of Railway System Engineering, University of Science and Technology) ;
  • Kim, Jung-Seok (Advanced Materials Research Team, Korea Railroad Research Institute) ;
  • Lim, Jae-Yong (Department of Mechanical Engineering) ;
  • Lee, Woo-Geun (Department of Railway System Engineering, University of Science and Technology) ;
  • Go, Yo-Han (Department of Advanced Materials Engineering, University of Science and Technology) ;
  • Kim, Young-Min (Implementation Research Division, Korea Institute of Materials Science) ;
  • You, Bong-Sun (Implementation Research Division, Korea Institute of Materials Science)
  • Received : 2016.04.07
  • Accepted : 2016.08.19
  • Published : 2016.08.31
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Abstract

In this study, the optimal welding condition of an extruded AZ61 magnesium alloy plate was investigated through evaluation of the mechanical properties and microstructure in the friction stir welding zones. The friction stir welding conditions considered in this study were the tool rotation speeds of 400, 600, and 800rpm and the welding speeds of 200, 300, and 400mm/min. To evaluate the welding strength, tensile and hardness tests were carried out. Microstructures of the welded regions were examined using optical microscopes. Under a tool rotation speed of 800rpm and welding speed of 200mm/min, the joint showed the best joining properties. The UTS, yield strength, and elongation of the welded region showed values of 79.0%, 65.4%, and 30.1%, respectively, of those of the base metal.

본 연구에서는 AZ61 압출 판재 마찰교반용접부의 기계적 강도 평가와 미세조직 평가를 수행하여 최적의 용접조건을 도출하였다. 용접조건은 용접 툴의 회전속도 400, 600, 800rpm, 이송속도 200, 300, 400mm/min으로 선정하였다. 인장시험 및 경도시험을 통해서 용접부의 기계적 강도 평가를 하였으며, 파단면 관찰과 용접부 단면 미세조직 관찰을 통해서 용접부의 결함 유무를 확인하였다. 용접부 특성 평가 결과 본 연구에서 제시한 용접조건 내에서 AZ61 압출 판재의 최적용접조건은 회전속도 800rpm, 이송속도 200mm/min이었고, 용접부의 인장강도, 항복강도 그리고 연신율은 모재 대비 79.0%, 65.4%, 30.1%로 측정되었다.

Keywords

References

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