열처리공학회지 (Journal of the Korean Society for Heat Treatment)

  • 제32권3호
  • /
  • Pages.118-123
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  • 2019
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  • 1225-1070(pISSN)
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  • 2508-4046(eISSN)
한국열처리공학회 (The Korean Society for Heat Treatment)
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주사음향현미경을 이용한 코발트기 초내열합금 미세조직에 관한 장시간 열영향에 대한 비파괴평가

Nondestructive Evaluation for Long-term Heat Treatment Effects on Microstructure of Co-base Superalloy by Scanning Acoustic Microscope

  • 이준희 (조선대학교 첨단소재공학과) ;
  • 김정석 (조선대학교 재료공학과)
  • lEE, JoonHee (Dep. of Advanced material and Engineering, Chosun University) ;
  • Kim, ChungSeok (Dep. of Materials Science and Engineering, Chosun University)
  • 투고 : 2019.05.08
  • 심사 : 2019.05.22
  • 발행 : 2019.05.30
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초록

The aim of this study investigates the feasibility of scanning acoustic microscope (SAM) with high frequency transducer for material degradation. The test specimen was prepared by artificial heat treatment of Co-base superalloy. The high frequency 200 MHz acoustic lens was used to generate the leaky surface acoustic wave (LSAW) on the test specimens. The matrix precipitates coarsened with thermal aging time, and then grow up to several tens of micrometers. The velocity of LSAW decreased with increasing aging time. Also, it has a good correlation between LSAW and hardness. Consequently, V(z) curve methods of SAM using high frequency transducer is useful tool to evaluate the heat treatment effects on microstructure.

키워드

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Fig. 1. Details of acoustic lens and interference of acoustic waves.

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Fig. 2. Interference of acoustic waves for multiple echoes V(z) curve.

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Fig. 3. Scanning acoustic microscope: (A) schemetic diagram and (b) photo of SAM.

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Fig. 4. Measurement configuration for V(z) curved of scanning acoustic microscope.

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Fig. 5. SEM images of matrix precipitates of the Cobase superalloy with heat treatment time.

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Fig. 6. Variation of Rockwell Hardness with heat treatment time.

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Fig. 7. The typical V(z) curves of As-received and 4,000 h heat treatment time.

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Fig. 8. Variation of leaky surface acoustic wave velocity with thermal aging time.

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Fig. 9. Variation of the elastic modulus with heat treatment time.

Table 1. Chemical composition of the Co-base superalloy

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Table 2. Artificial aging heat treatment conditions

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참고문헌

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