• 제목/요약/키워드: Indentation Technique

검색결과 146건 처리시간 0.029초

계장화 압입시험법을 이용한 보일러 설비의 고온 기계적 물성 측정과 수명 평가 (High-temperature Mechanical Properties Measurement and Life Assessment of Boiler Equipment by Instrumented Indentation Technique)

  • 노동성;홍정화;김광호;이정준
    • 한국안전학회지
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    • 제24권3호
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    • pp.1-6
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    • 2009
  • Recently power plants and oil refineries are focusing on capacity enlargement for better efficiency through higher temperature and higher pressure. Thickness of boiler tubes becomes lessened due to oxidation and erasion caused by high temperature bums gas flowing over tubes outside. Accordingly, mechanical stress of tubes is increasing and that is a critical factor to make a crack and fracture. To prevent those sorts of accidents, aging assessment for proper periodic repair and replacement should be conducted reliably and reasonably. We performed IIT test on Cr-Mo steel, one of the most heat-resistant materials for facilities in power plants, and we report the test result and the considerable effectiveness of IIT test.

계장화 압입시험법에 의한 Alloy 617 용접 물성치 측정 (Measurement of Weld Material Properties of Alloy 617 Using an Instrumented Indentation Technique)

  • 송기남;홍성덕;노동성;이주하;홍정화
    • Journal of Welding and Joining
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    • 제31권5호
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    • pp.41-46
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    • 2013
  • Different microstructures in the weld zone of a metal structure such as a fusion zone or heat affected zone are formed as compared to the parent material. Thus, the mechanical properties in the weld zone are different from those in the parent material. As the basic data for reliably understanding the structural characteristics of a welded PCHE specimen to be made of Alloy 617, the mechanical properties in the weld zone and parent material for a Alloy 617 plate are measured using an instrumented indentation technique in this study.

계장화 압입시험법에 의한 SUS316L판의 용접부 기계적 물성치 측정 (Measurement of Weld Mechanical Properties of SUS316L Plate Using an Instrumented Indentation Technique)

  • 송기남;홍성덕;노동성
    • Journal of Welding and Joining
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    • 제31권2호
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    • pp.37-42
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    • 2013
  • Different microstructures in the weld zone of a metal structure such as a fusion zone or heat affected zone are formed as compared to the parent material. Thus, the mechanical properties in the weld zone are different from those in the parent material. As the basic data for reliably understanding the structural characteristics of welded PCHE prototype made of SUS316L, the mechanical properties in the weld zone and parent material for a SUS316L plate are measured using an the instrumented indentation technique in this study.

계장형 압입시험법에 의한 원자력 구조재료 용접 물성치 측정 (Measurement of Mmechanical Properties in Weld Zone of Nuclear Material using an Instrumented Indentation Technique)

  • 송기남;노동성
    • Journal of Welding and Joining
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    • 제30권3호
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    • pp.51-56
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    • 2012
  • Different microstructures in the weld zone of a metal structure including a fusion zone and heat affected zone are formed as compared to the base material. Thus, the mechanical properties in the weld zone are different from those in the base material. As the basic data for reliably understanding the structural characteristics of welded nuclear material, the mechanical properties in the weld zone and base material for a Zircaloy-4 strap and Hastelloy${(R)}$-X alloy strap are measured using an instrumented indentation technique (IIT) in this study.

Advanced Indentation Studies on the Effects of Hydrogen Attack on Tensile Property Degradation of Heat-Resistant Steel Heat-Affected Zones

  • Choi, Yeol;Jang, Jae-il;Lee, Yun-Hee;Kwon, Dongil;Kim, Jeong-Tae
    • Corrosion Science and Technology
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    • 제2권6호
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    • pp.266-271
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    • 2003
  • Safety diagnosis of various structural components and facilities is indispensable for preventing catastrophic failure of material by time-dependent and environment accelerating degradation. Also, this diagnosis of operating components should be done periodically for safe maintenance and economical repair. However, conventional standard methods for mechanical properties have the problems of bulky specimen, destructive procedure and complex procedure of specimen sampling. So, a non-destructive and simple mechanical testing method using small specimen is needed. Therefore, an advanced indentation technique was developed as a potential method for non-destructive testing of in-field structures. This technique measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation such as yield strength, tensile strength and work-hardening index. In this paper, we characterized the tensile properties including yield and tensile strengths of the V-modified Cr-Mo steels in petro-chemical and thermo-electrical plants. And also, the effects of hydrogen-assisted degradation of the V-modified Cr-Mo steels were analyzed in terms of work-hardening index and yield ratio.

Non-equibiaxial residual stress evaluation methodology using simulated indentation behavior and machine learning

  • Seongin Moon;Minjae Choi;Seokmin Hong;Sung-Woo Kim;Minho Yoon
    • Nuclear Engineering and Technology
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    • 제56권4호
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    • pp.1347-1356
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    • 2024
  • Measuring the residual stress in the components in nuclear power plants is crucial to their safety evaluation. The instrumented indentation technique is a minimally invasive approach that can be conveniently used to determine the residual stress in structural materials in service. Because the indentation behavior of a structure with residual stresses is closely related to the elastic-plastic behavior of the indented material, an accurate understanding of the elastic-plastic behavior of the material is essential for evaluation of the residual stresses in the structures. However, due to the analytical problems associated with solving the elastic-plastic behavior, empirical equations with limited applicability have been used. In the present study, the impact of the non-equibiaxial residual stress state on indentation behavior was investigated using finite element analysis. In addition, a new nonequibiaxial residual-stress prediction methodology is proposed using a convolutional neural network, and the performance was validated. A more accurate residual-stress measurement will be possible by applying the proposed residual-stress prediction methodology in the future.

발전설비 주요배관 신뢰도 확보를 위한 연속압입시험 적용 (Application of Continuous Indentation Technique for Reliability Evaluation in Power Plant Facilities)

  • 박상기;안연식;정계조;조용상;최열
    • 비파괴검사학회지
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    • 제24권2호
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    • pp.158-162
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    • 2004
  • 발전설비에서 용접 구조물의 신뢰성은 매우 중요하며, 구조물 신뢰성평가를 위해서는 재료물성의 정확한 평가에 근거되어야 한다. 발전설비의 건설중 용접부의 물성평가는 실제 용접부에서의 파괴시험이 어려우므로 현장 용접부와 유사하게 용접, 시험한 결과인 PQR(Procedure Qualification Record)에 의해서만 보증을 하고 있다. 이런 문제점을 해결하기 위하여 현장 용접부에 대하여 비파괴적으로 기계물성 측정이 가능한 연속압입시험법을 적용하였다. 연속압입시험법은 압입시 압입하중-깊이를 측정하여 항복강도, 인장강도 그리고 가공경화지수와 같은 기계적 특성들의 분석이 가능한 시험법으로, 화력 발전소 건설 및 운전중 주증기관과 재열증기관의 기계인장물성을 평가하기 위하여 적용하였다.

Hole effect를 고려한 AAO(Anodic Aluminum Oxide) 구조물의 물성치에 대한 연구 (The Study on Properties of AAO(Anodic Aluminum Oxide) Structures with Hole Effect)

  • 고성현;이대웅;지상은;박현철;이건홍;황운봉
    • 한국정밀공학회지
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    • 제21권4호
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    • pp.186-193
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    • 2004
  • Porous anodic alumina has been used widely for corrosion protection of aluminum surfaces or as dielectric material in micro-electronics applications. It exhibits a homogeneous morphology of parallel pores which can easily be controlled between 10 and 400nm. It has been applied as a template for fabrication of the nanometer-scale composite. In this study, mechanical properties of the AAO structures are measured by the nano indentation method. Nano indentation technique is one of the most effective methods to measure the mechanical properties of nano-structures. Basically, hardness and elastic modulus can be obtained by the nano-indentation. Using the nano-indentation method, we investigated the mechanical properties of the AAO structure with different size of nano-holes. In results, we find the hole effect that changes the mechanical properties as size of nano hole.

나노 인덴테이션의 하중-변위 곡선을 이용한 표면처리강판 코팅층의 기계적 특성 결정 (Determination of the mechanical properties of the coated layer in the sheet metal using load-displacement curve by nanoindentation technique)

  • 고영호;이정민;김병민
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 춘계학술대회 논문집
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    • pp.148-151
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    • 2004
  • Mechanical properties such as Young's modulus and hardness of thin film in coated steel are difficult to determine by nano-indentation from the conventional analysis using the load-displacement curve. Therefore, an analysis of the nano-indentation loading curve was used to determine the Young's modulus, hardness and strain hardening exponent. A new method is recently being developed for plasticity properties of materials from nano-indentation. Elastic modulus of the thin films shows relatively small influence whereas yield strength and strain hardening are found to have significant effect on measured data. The load-displacement behavior of material tested with a Berkovich indenter and nano-indentation continuous stiffness method is used to measure the modulus and hardness through thin films.

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향상된 구형압입 고무 물성평가법 (Enhanced Spherical Indentation Techniques for Rubber Property Evaluation)

  • 황규민;오중수;이형일
    • 대한기계학회논문집A
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    • 제33권12호
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    • pp.1357-1365
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    • 2009
  • In this study, we enhance the numerical approach of Lee et al.$^{(1)}$ to spherical indentation technique for property evaluation of hyper-elastic rubber. We first determine the friction coefficient between rubber and indenter in a practical viewpoint. We perform finite element numerical simulations for deeper indentation depth. An optimal data acquisition spot is selected, which features sufficiently large strain energy density and negligible frictional effect. We then improve two normalized functions mapping an indentation load vs. deflection curve into a strain energy density vs. first invariant curve, the latter of which in turn gives the Yeoh-model constants. The enhanced spherical indentation approach produces the rubber material properties with an average error of less than 3%.