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Marco and Microscopic Observations of Fatigue Crack Growth in Friction Stir Welded 7075-T651 Aluminum Alloy Plates

마찰교반용접된 7075-T651 알루미늄 판재의 피로균열전파의 거시적 및 미시적 관찰

  • Kong, Yu-Sik (A+ LINC, Pukyong National University) ;
  • Kim, Seon-Jin (Department of Mechanical & Automotive Engineering, Pukyong National University)
  • 공유식 (부경대학교 A+ LINC 사업단) ;
  • 김선진 (부경대학교 기계자동차공학과)
  • Received : 2014.01.02
  • Accepted : 2014.03.25
  • Published : 2014.04.30

Abstract

In this paper, in order to investigate the effects of marco and microscopic observations of fatigue crack growth in friction stir welded (FSWed) 7075-T651 aluminum alloy plates, fatigue crack growth tests were performed under constant amplitude loading condition at room temperature with three different pre-cack locations, namely base metal (BM-CL) and two kinds of pre-crack locations in welded joints, weld metal (WM-CL) and heat affected zone (HAZ-CL) specimens. The fatigue crack growth behavior of FSWed 7075-T651 aluminum alloy plates were discussed based on the marco and microscopic fractographic observations. The marcoscopic aspects of surface crack growth path for BM-CL and HAZ-CL specimens indicate relatively straight lines, however, the crack growth paths of WM-CL specimens grow first straight and by followed toward the TMAZ and HAZ. The microscopic aspects of fatigue fracture for BM-CL and HAZ-CL specimens indicate typical fatigue striation, but WM-CL showed intergranular fracture pattern by micro structural changes of FSW process.

Keywords

References

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