Journal of the Korean Institute of Gas (한국가스학회지)

The Korean Institute of GAS (한국가스학회)
권호 표지

Assessment of Yield Characteristics of Gas Pipeline Materials by Observing Surface-Local Deformation

미소 표면변형 관찰을 통한 가스배관 부재의 항복특성 평가

  • Lee, Yun-Hee (Division of Quality of Life, Korea Research Institute of Standards and Science) ;
  • Baek, Un-Bong (Division of Quality of Life, Korea Research Institute of Standards and Science) ;
  • Cheong, In-Hyeon (Division of Quality of Life, Korea Research Institute of Standards and Science) ;
  • Nahm, Seung-Hoon (Division of Quality of Life, Korea Research Institute of Standards and Science) ;
  • Lee, Sang-Houck (K-Technocon Co., Ltd.)
  • 이윤희 (한국표준과학연구원 삶의질표준본부) ;
  • 백운봉 (한국표준과학연구원 삶의질표준본부) ;
  • 정인현 (한국표준과학연구원 삶의질표준본부) ;
  • 남승훈 (한국표준과학연구원 삶의질표준본부) ;
  • 이상혁 ((주) 케이테크노콘)
  • Published : 2008.06.30
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Abstract

A combination of the instrumented indentation and 3D morphology measurement has been tried in order to perform a real-time property measurement of degraded materials in gas pipelines; three-dimensional indent morphologies were recorded using a reflective laser scanner after a series of insturmented indentations on three metallic specimens. Dimensions of the permanent deformation zone and contact boundary were analyzed from the cross-sectional profile over an remnant indent and used for estimating yield strength and hardness, respectively. Estimated yield strength was comparable with that from uniaxial tensile test and actual hardness implying material pile-up effects was lower than the calculated value from indentation curve by $20{\sim}30%$. It means that this 3D image analysis can explain the material pile-up effects on the contact properties. Additionally, a combined system of indentation and laser sensor was newly designed by modifying a shape of the indentation loading fixture.

가스배관 열화부재의 실시간 역학물성 측정기술로 계장화 압입과 압입흔적 입체측정의 융합이 시도되었다. 압입하중-변위곡선을 계장화 압입시험으로 획득한 후 반사식 레이저 스캔너를 이용하여 압입흔적을 3차원으로 관찰하였다. 압흔 단면프로파일로부터 소성역 크기와 실제 접촉경계를 분석할 수 있었고, 두 값을 이용하여 소재의 항복강도와 경도를 계산하였다. 항복강도는 단축 인장시험에서 얻어진 값과 유사한 경향을 나타내었고, 경도는 재료쌓임 영향으로 압입곡선에서 계산된 값에 비해 $20{\sim}30%$ 낮은 값을 나타내었으나 최대 인장강도와 정량적인 관련성이 있음을 확인할 수 있었다. 덧붙여 압입하중 인가부의 형태를 수정하여 압입시험과 동시에 압흔주변 형상변화를 측정하기 위한 시스템도 고안되었다.

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