• 제목/요약/키워드: Cr-Mo 강

검색결과 203건 처리시간 0.036초

화력발전용 로터강의 초기 변형률법에 의한 장시간 크리프 수명 및 강도 예측 (Long Time Creep Strength and Life Prediction of Steam Turbine Rotor Steel by Initial Strain Method)

  • 오세규;정순억
    • 대한기계학회논문집
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    • 제17권6호
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    • pp.1321-1329
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    • 1993
  • 본 연구에서는 이들보다 매우 간단한 IS법, 즉 초기 변형률법(ISM: initial strain method)에 의한 크리프 수명예측식을 고안하여, 현재 화력발전용 고압 로터강 에 사용되고 있는 1%Cr-Mo-V강과 발전소 효율향상을 위해 최근 국내최초로 개발된 12% Cr강에 대하여 도출하였고, 이 도출식이 앞에서 언급한 여러 파라메트에 의한 결과와 비교 평가하여 장시간 강도 및 수명예측식으로 사용될 수 있음을 입증하였다.

발전설비용 2.25Cr-1Mo 강의 시효에 의한 기계적 강도 특성 변화에 대한 연구 (A Study on the Mechanical Strength Change by Thermal Aging of 2.25Cr-1Mo Steel)

  • 양현태;김상태
    • 대한기계학회논문집A
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    • 제24권7호
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    • pp.1771-1778
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    • 2000
  • The purpose of this study is to investigate the thermal embrittlement and the mechanical properties of 2.25Cr-1Mo steel aged at high temperature for the extended periods. Original, aged artificiall y and used material were tested to obtain the tensile strength, hardness and impact absorbed energy. Tensile strength, hardness and impact absorbed energy decreased with the increasing aging time. The carbide morphology with the thermal embrittlement was found to contribute to the mechanical property change by X-Ray diffraction method.

12% Cr 로터강의 강도 개선에 관한 연구 (Study on the Improvement of Strength for 12% Chromium Steel Rotor)

  • 장윤석;오세욱
    • 한국해양공학회지
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    • 제3권2호
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    • pp.125-137
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    • 1989
  • To check technical improvement in the soundness and strength of 12% Cr steel rotor, a 25 tons of rotor with 65 tons of ingot was made in real size and was cut to pieces to take test samples, and the various mechanical tests such as impact, tensile, creep, and fatigue were carried out. The strengths are compared with those of 1% Cr-Mo-V rotor of same size. Microstructures of the samples are examined and reviewed. The results can be summarized as follows. 1) Fracture appearance transition temperatures are 80.deg. C at the center part and 60.deg. C near surface of 12% Cr rotor, and 8.deg. C near surface of 1% Cr-Mo-V rotor. 2) Comparative rapid softening occurs at higher temperatures above 600.deg. C for 12% Cr steel and 550.deg. C for 1% Cr-Mo-V steel in tension tests. 3) Fatigue crack propagation rate of 12% Cr steel is almost same as that of 1% Cr-Mo-V steel at the same corresponding surface part of the rotors. The crack growth rate of center part of 12% Cr rotor is faster than near surface part of the rotor, and the crack growth rate at the load condition of R=0.04 is slower than that of the load condition of R=0.5 for both 12% Cr steel and 1% Cr-Mo-V steel. 4) Crack growth rate of radial direction near surface of 12% Cr rotor is faster than that of transverse direction at the same part because of the difference in residual stresses. 5) Both creep and fatigue strengths of 12% Cr steel are superior to those of 1% Cr-Mo-V steel and the difference is thought the effect of climb and glide controlled creep by solid solution of alloying elements and dispersion of carbides.

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12% Cr 로터강의 강도 개선에 관한 연구 (Study on the Improvement of Strength for 12% Chromium Steel Rotor)

  • 장윤석;오세욱
    • 한국해양공학회지
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    • 제3권2호
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    • pp.625-625
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    • 1989
  • To check technical improvement in the soundness and strength of 12% Cr steel rotor, a 25 tons of rotor with 65 tons of ingot was made in real size and was cut to pieces to take test samples, and the various mechanical tests such as impact, tensile, creep, and fatigue were carried out. The strengths are compared with those of 1% Cr-Mo-V rotor of same size. Microstructures of the samples are examined and reviewed. The results can be summarized as follows. 1) Fracture appearance transition temperatures are 80.deg. C at the center part and 60.deg. C near surface of 12% Cr rotor, and 8.deg. C near surface of 1% Cr-Mo-V rotor. 2) Comparative rapid softening occurs at higher temperatures above 600.deg. C for 12% Cr steel and 550.deg. C for 1% Cr-Mo-V steel in tension tests. 3) Fatigue crack propagation rate of 12% Cr steel is almost same as that of 1% Cr-Mo-V steel at the same corresponding surface part of the rotors. The crack growth rate of center part of 12% Cr rotor is faster than near surface part of the rotor, and the crack growth rate at the load condition of R=0.04 is slower than that of the load condition of R=0.5 for both 12% Cr steel and 1% Cr-Mo-V steel. 4) Crack growth rate of radial direction near surface of 12% Cr rotor is faster than that of transverse direction at the same part because of the difference in residual stresses. 5) Both creep and fatigue strengths of 12% Cr steel are superior to those of 1% Cr-Mo-V steel and the difference is thought the effect of climb and glide controlled creep by solid solution of alloying elements and dispersion of carbides.

X20CrMoV12.1강의 열화에 따른 기계적특성 평가 (The Evaluation of Mechanical Property of X20CrMoV12.1 Boiler Tube Steels)

  • 김범수;이성호;김두수;정남근
    • 동력기계공학회지
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    • 제8권3호
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    • pp.18-22
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    • 2004
  • Boiler is one of the most important utilities providing steam to turbine in order to supply mechanical energy in thermal power plant. It is composed of thousands of tubes for high efficient heat transfer. The material for boiler tubes is used in such high temperature and pressure condition as $540^{\circ}C$, 22MPa. The boiler tube material is required to resist creep damage, fatigue cracking, and corrosion damages. 2.25%Cr-1Mo steel is used for conventional boiler tubes, and austenitenite stainless steel is used for higher temperature boiler tubes. But the temperature and pressure of steam in power plant became higher for high plant efficiency. So, the property of boiler tube material must be upgaded to fit the plant property. Several boiler tube material was developed to fit such conditions. X20CrMoV12.1 steel is also developed in 1980's and used for superheater and reheater tubes in supercritical boilers. The material has martensite microstructures which is difficult to evaluate the degradation. In this thesis, degrade the X20CrMoV12.1 steel at high temperatures in electric furnace, and evaluate hardness with Vickers hardness tester and strengths with Indentation tester.

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열화된 1Cr-1Mo-0.25V강의 DBTT 크기효과 보정에 관한 연구 (Normalization of DBTT Size Effect far Aged 1Cr-lMo-0.25V Steel)

  • 남승훈;김엄기;이대열
    • 대한기계학회논문집A
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    • 제25권12호
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    • pp.2109-2115
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    • 2001
  • Miniaturized specimen technology is useful to characterize the mechanical behavior when it is difficult to sample the material enough for the test. In this study, two kinds of miniaturized Charpy impact specimens(i.e., miniaturized specimen with side groove and without side groove) of aged 1Cr- lMo-0.25V steel were prepared and tested. The relationship between the extent of degradation in terms of ductile brittle transition temperature(DBTT) and the fracture stress of 1Cr-1Mo-0.25V steel was established. The fracture stress obtained from miniaturized specimen without side groove turned out to be linearly related with the DBTT of standard specimen. Therefore the fracture toughness of aged turbine rotor steel might be evaluated by the fracture stress. In addition, the correlation between DBTT of standard specimen and that of miniaturized specimen was investigated. As the results of normalizing DBTT by maximum elastic tensile stress, the normalized DBTT of miniaturized specimen without side groove allows one to estimate that of standard specimen.

동위원소희석 유도결합플라스마질량분석법에 의한 저 합금강 표준시료중의 Ni, Cr, Mo의 분석 (Determination of Ni, Cr, Mo in Low Alloy Steel Reference Materials by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry)

  • 서정기;우진춘;민형식;임명철
    • 분석과학
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    • 제16권1호
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    • pp.82-89
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    • 2003
  • Isotope dilution mass spectrometry (IDMS) was applied to the determination of Ni, Cr, Mo in low alloy steel reference materials. The Mo isotope ratio measurement was performed by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP/MS) using ammonia as a reaction cell gas. In the case of Ni and Cr measurement, all data were obtained at medium resolution mode (m/${\Delta}m=3000$) of double focusing sector field high resolution inductively coupled plasma mass spectrometry (HR-ICP/MS). For the method validation of the technique was assessed using the certified reference materials such as NIST SRM 361, NIST SRM 362, NIST SRM 363, NIST SRM 364, NIST SRM 36b. This method was applied to the determination of Ni, Cr and Mo in low alloy steel sample (CCQM-P25) provided by NMIJ for international comparison study.

SO2 가스 환경 하에서 1.25Cr-0.5Mo 강의 부식 및 강도 저하 특성 (Corrosion and Strength Degradation Characteristics of 1.25Cr-0.5Mo Steel under SO2 Gas Environment)

  • 정광후;김성종
    • 한국표면공학회지
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    • 제51권3호
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    • pp.149-156
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    • 2018
  • The corrosion and strength degradation characteristics of 1.25Cr-0.5Mo steels were studied under $650^{\circ}C$ in $76%N_2+6%O_2+16%CO_2+2%SO_2$ gas condition up to 500 hrs. Corroded specimens were characterized by weight gain, scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDS), and X-ray diffraction(XRD). The tensile test was conducted to evaluate the mechanical strength and fracture mode with corrosion at high temperature. As the results of the experiments, thick Fe-rich oxide layers over $200{\mu}m$ were formed on the surface within 500 hrs. The thick oxide layers are formed with reduction of the cross-sectional area of the specimens. Thus, the strength tended to decrease with reduction of the cross-sectional area.

9Cr-lMo강에 대한 Laser 및 SMAW 용접부의 열분포 특성 비교 (The Comparison of the Heat Distribution and Characteristic between the Laser & SMAW Welds of 9Cr-lMo Steel.)

  • 오종인;방한서;김영표;박형근
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2004년도 추계학술발표대회 개요집
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    • pp.118-120
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    • 2004
  • Recently 9Cr-1Mo azzoy is used in the Nuclear power plant due to its special properties. This material has the merit of high-strength resistance and corrosion resistance. Therefore the demand for this alloy is dramatically increased in the Nuclear power, petro-chemical complex etc. Re various research has been conducted to improve the material properties of this alloy. In spite of this circumstance, detail research in the area of welding process of this alloy is yet to be expanded In this study the numerical non-linear heat transfer analysis of laser welding which may possibly replace the conventional SMAW fabrication of 9Cr-1Mo steel has been carried out.

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초음파 비선형성을 이용한 2.25Cr-1Mo 강의 열화도 평가 (Evaluation of Degradation of 2.25Cr-1Mo Materials using the Nonlinear Acoustic Effect)

  • 최윤호;김현묵;장경영;박익근
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.222-227
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    • 2001
  • Nonlinear acoustic effect has been considered as an effective tool for the evaluation of material degradation. In this paper, the applicability of nonlinear acoustic effect to the evaluation of degradation of 2.25Cr-1Mo steel is investigated. Firstly, a number of 2.25Cr-1Mo steel samples were heat-treated, and their damage mechanism was examined. Secondly, Ultrasonic nonlinear parameter was measured. Nonlinear acoustic parameter was found to be clearly sensitive to the material degradation.

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