Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Relief of Residual Stress and Estimation of Heat-Treatment Characteristics for Al6061 Alloy by Cryogenic Heat Treatment

극저온 열처리에 의한 Al6061 합금의 잔류응력 제거 및 열처리 특성 평가

  • Ko, Dae-Hoon (Precision Manufacturing System Division, Pusan Nat'l Univ.) ;
  • Park, Ki-Jung (Dept. of Materials Science and Engineering, Pusan Nat'l Univ.) ;
  • Cho, Young-Rae (Dept. of Materials Science and Engineering, Pusan Nat'l Univ.) ;
  • Lim, Hak-Jin (Defense Product Technical Research Laboratory, Poongsan Corporation) ;
  • Lee, Jung-Min (Defense Product Technical Research Laboratory, Poongsan Corporation) ;
  • Kim, Min-Byung (Department of Mechanical Engineering, Pusan Nat'l Univ.)
  • 고대훈 (부산대학교 대학원 정밀가공시스템) ;
  • 박기정 (부산대학교 재료공학부) ;
  • 조영래 (부산대학교 재료공학부) ;
  • 임학진 ((주)풍산 방산기술연구소) ;
  • 이정민 ((주)풍산 방산기술연구소) ;
  • 김병민 (부산대학교 기계공학부)
  • Received : 2010.12.08
  • Accepted : 2011.07.20
  • Published : 2011.10.01
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Abstract

The purpose of this study is to relieve the residual stress of Al6061 using cryogenic heat treatment. Experimental T6 and cryogenic heat treatments were carried out to define the convective heat-transfer coefficient, which was then applied in the finite-element method (FEM) to predict the residual stress. The predicted residual stress was compared with the residual stress measured by X-ray diffraction (XRD), and the results were in good agreement. The mechanical properties were estimated by measuring the electrical conductivity and hardness. In addition, the size and formation of the precipitations were observed by TEM and XRD analysis for both T6 and cryogenic heat treatments. The effects of the cryogenic heat treatment on the residual stress, mechanical properties, and precipitation of Al6061 alloys were thus confirmed.

본 연구의 목적은 극저온 열처리를 통해 Al6061 의 열처리 잔류응력을 제거하는 것이다. 이를 위해 유한요소해석을 이용하여 열처리 잔류응력을 예측하였으며, 열처리 조건에 따른 각 단계별 대류 열전달계수를 T6 와 극저온 열처리 실험을 수행하여 결정하였다. 예측된 잔류응력 결과는 X 선회절법(XRD)으로 측정된 잔류응력 결과와 비교하여 유한요소해석 결과의 타당성을 확인하였다. 또한 T6 와 극저온 열처리에 대해 각각 전기 전도도와 경도를 측정하여 기계적 특성을 평가하고 TEM 관찰과 XRD 회절 분석을 통해 석출물의 크기 및 성분을 파악하였다. 이를 통해 Al6061 의 T6 열처리와 비교하여 극저온 열처리를 적용함에 따른 잔류응력, 기계적 특성 및 미세조직변화를 조사하였다.

Keywords

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