• 제목/요약/키워드: Super Duplex Stainless Steel

검색결과 57건 처리시간 0.027초

클래드강 적용을 위한 선급용 강재의 열처리 특성 평가 (Clad Steel for Application of Hull Structure)

  • 신용택
    • Journal of Welding and Joining
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    • 제33권5호
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    • pp.20-25
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    • 2015
  • Clad steel has good corrosion resistance and mechanical properties arising from the hot rolling of dissimilar metals, such as carbon steel and stainless steel. However both good corrosion resistance from the cladding plate material(stainless steel) and mechanical properties from the base plate material (carbon steel) are difficult to obtain because the different steels display opposite behaviors during the cladding process. In order to make clad steel for application in the hulls of ships, proper materials selection and heat-treatment conditions are necessary. In this study, mechanical properties of base plate materials with different chemical composition were evaluated according to heat condition of cladding plate material.

시효된 수퍼 2상 스테인리스강의 피로균열 진전시 발생하는 음향방출신호의 시간-주파수 분석 (Time-Frequency Analysis of AE Signals at Fatigue Crack Propagation of Aged Super Duplex Stainless Steels)

  • 남기우;이상기;도재윤;강창룡
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2000년도 추계학술대회 논문집
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    • pp.20-25
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    • 2000
  • lh deleterious Cr, Mo rich -$\sigma$phase is a hard embrittling precipitate, which forms between MU)-900 $^{\circ}C$, often associated with a reduction in both impact properties and corrosion reshame. On this study, After aging at MU) "C, fatigue crack propagation induced by a phase precipitation was evaluated and time-frequency analysis of acoustic emission was conducted It was possible to find fracture mechanism by a phase precipitation due to time-frequency anulysis of acoustic emission signals.nals.

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슈퍼 2상 스테인리스강의 미세조직 및 기계적 성질에 미치는 시효의 영향 (Effect of Aging on the Microstructure and Mechanical Properties in Super Duplex Stainless Steel)

  • 김수천;강창룡
    • 한국해양공학회지
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    • 제23권3호
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    • pp.40-45
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    • 2009
  • With the increase in the annealing temperature, the volume fraction of austenite phase increased and the volume fraction of ferrite phase decreased. In compliance with the addition of N, not only the volume fraction of austenite phase was increased but also the austenite structure was made larger. Volume fraction of ${\sigma}$ phase was increased by decreasing of the volume fraction of ferrite phase, with the increase in the aging time and in compliance with the addition of N. As increasing in volume fraction of ${\sigma}$ phase, tensile strength and hardness increased, while elongation and impact value decreased. Elongation slowly decreased and impact value rapidly decreased at the early stage of aging. By the added N, tensile strength, elongation, hardness and impact value was increased.

SDSS (Super Duplex Stainless Steel) 강관의 미세조직 및 부식특성에 미치는 열처리 온도의 영향 (The Influence of Heat Treatment Temperature on Microstructure and Corrosion Behavior of SDSS Tube)

  • 이인섭;천창석;임태홍;한윤호;이면학
    • 한국표면공학회지
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    • 제48권6호
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    • pp.329-334
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    • 2015
  • The aim of this paper is to determine the proper heat treatment temperature for SDSS tube production without ${\sigma}$-phase precipitation. When Mother steel tube was heat treated at $800^{\circ}C$ temperature, relatively a large amount of ${\sigma}$-phase precipitated and grain refinement of ferrite phase occurred simultaneously. However, in Pilgered and Drawn steel tubes, grain refinement of the ferrite phase did not occur and a small amount of ${\sigma}$-phase precipitated. For all three types of steel tubes, the pitting potential was reduced to 2/5 or less compared with the untreated one and corrosion also occurred in the salt spray test due to the precipitation of ${\sigma}$-phase. When heat treatment temperature was $900^{\circ}C$, grain refinement of the ferrite phase occurred and very little ${\sigma}$-phase precipitated in Pilgered and Drawn steel tubes. But when heat treatment was done at $1,000^{\circ}C$ temperature, all three types of steel tubes had a similar corrosion properties of that of untreated one and also corrosion did not occur in the salt spray test, as ${\sigma}$-phase did not precipitate. Therefore, the optimum heat treatment temperature range is determined to be more than $1000^{\circ}C$ for the SDSS at which corrosion does not occur.

인터모달 트램 차체 경량화를 위한 신개발 스테인레스 강재 적용성 연구 (A study on the applicability of newly developed stainless steel for weight reduction of carbody of intermodal tram)

  • 서승일;김정국;정현승
    • 한국산학기술학회논문지
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    • 제17권3호
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    • pp.457-463
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    • 2016
  • 신규 개발된 초연성 듀플렉스 스테인레스강은 강도와 연성이 우수하기 때문에 철도차량 차체에 적용하여 경량화와 가공 효율화에 기여할 수 있다. 본 연구에서는 듀플렉스 스테인레스강의 장점을 인터모달 트램 차체에 활용하기 위해 점용접성 시험을 수행하였다. 다양한 두께 (0.4mm에서 5.0mm까지)의 시편을 가공하고 점용접 시험을 통해 적정 용접조건을 찾아내었다. 인장하중 시험을 통해 점용접 이음의 인장-전단 강도를 평가하였고, 품질을 확인하기 위해 너깃 지름을 측정하였다. 인장-전단 하중 시험 결과의 분석을 통해, 이음부의 인장-전단 강도는 입열 파라미터에 비례함을 알 수 있었다. 인장-전단 강도와 너깃 지름는 모두 규격에서 요구하는 기준을 만족함도 입증되었다. 전체적인 용접성 시험 결과, 듀플렉스 스테인레스강 소재는 인터모달 트램 차체에 효과적으로 활용될 수 있음을 확인하였다.

산성 염화물 환경에서 F53 슈퍼 듀플렉스 스테인리스강의 2 상간의 공식 거동 연구 (Investigation of the pitting corrosion behavior between the constituent phases in F53 super duplex stainless steel in acidified chloride environments)

  • 김순태;공경호;이인성;박용수;이종훈;김두현
    • Corrosion Science and Technology
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    • 제13권3호
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    • pp.95-101
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    • 2014
  • The pitting corrosion behaviors between the constituent phases in F53 super duplex stainless steel (SDSS) in acidified chloride environments were investigated using a critical pitting corrosion temperature test, a potentiodynamic anodic polarization test, and the microstructure analyses through a SEM-EDS and a SAM. As the solution annealing temperature decreased from $1150^{\circ}C$ to $1050^{\circ}C$, the ${\gamma}$-phase fraction increased whereas the ${\alpha}$-phase fraction decreased. The pitting potential and the critical pitting temperature increased with a decrease of solution annealing temperature, thereby increasing the resistance to pitting corrosion. The pitting corrosion of the SDSS was selectively initiated at the ${\alpha}$-phases because the PREN (pitting resistance equivalent number, PREN = %Cr+3.3%Mo+30%N) value of the ${\gamma}$-phase is much larger than that of the ${\alpha}$-phase, irrespective of the solution annealing temperature. The pitting corrosion was finally propagated from the ${\alpha}$-phase to the ${\gamma}$-phase. The decrease of solution annealing temperature enhanced the resistance to pitting corrosion greatly in acidified chloride environments due to a decrease of PREN difference between the ${\gamma}$-phase and the ${\alpha}$-phase, that is, a decrease of $PREN{\gamma}$ by dilution of N in ${\gamma}$-phase with an increase in the ${\gamma}$-phase volume fraction and an increase of $PREN{\alpha}$ by enrichment of Cr and Mo in the ${\alpha}$-phase with a decrease in the ${\alpha}$-phase volume fraction.

수퍼 이상 스테인리스강의 내식성에 미치는 입열의 영향 (The Effect of Heat Input on the Pitting Corrosion Resistance of the Weld of Super Duplex Stainless Steel)

  • 성희준;주정권;이철환;김대순
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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    • pp.134-135
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    • 2004
  • 해양구조물의 설치 환경 및 제품의 사용환경이 악화됨에 따라서 높은 내식성을 보이는 수퍼 이상 스테인리스강(이하: SDSS)의 사용이 많아지고 있다. 해양 구조물에 사용되는 SDSS는 대부분이 파이프자재로서 내부에서의 접근이 불가능하여 용접은 GTAW로 초층을 용접하여 이면 비드를 형성시키는 One side 용접법이 채택되고 있다. (중략)

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슈퍼 듀플렉스 스테인레스강의 미세조직 및 기계적 특성에 미치는 열처리 후 냉각속도의 영향 (Effects of the Cooling Rate After Annealing Treatment on the Microstructure and the Mechanical Properties of Super-Duplex Stainless Steel)

  • 권기현;나영상;유위도;이종훈;박용호
    • 대한금속재료학회지
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    • 제50권10호
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    • pp.735-743
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    • 2012
  • The aim of this study was to analyze the effect of the cooling rate after heat treatment on the microstructure and mechanical properties of 2507 duplex stainless steels. Heat treatment was carried out at $1050^{\circ}C$ for 1 hr, followed by controlled cooling. The cooling rates were $175.6{\times}10^{-3}^{\circ}C/s$, $47.8{\times}10^{-3}^{\circ}C/s$, $33.3{\times}10^{-3}^{\circ}C/s$, $16.7{\times}10^{-3}^{\circ}C/s$, $11.7{\times}10^{-3}^{\circ}C/s$, $5.8{\times}10^{-3}^{\circ}C/s$ and $2.8{\times}10^{-3}^{\circ}C/s$, which resulted in variations of the microstructure, such as the fractional change of the ferrite phase and sigma phase formation. Fatigue, hardness, impact and tensile tests were performed on the specimens with different cooling rates. The precipitation of the ${\sigma}$ phase caused a hardness increase and a sharp decrease of toughness and tensile elongation. The fatigue limit of the sample with a cooling rate of $5.8{\times}10^{-3}^{\circ}C/s$ was 26 MPa higher than that of the sample with a cooling rate of $175.6{\times}10^{-3}^{\circ}C/s$. Our observations of the fracture surface confirmed that the higher fatigue resistance of the specimen with a cooling rate of $5.8{\times}10^{-3}^{\circ}C/s$ was caused by the delay of the fatigue crack growth, in addition to higher yield strength.

SAF 2507 스텐레스강의 열간단조해석에서 가공열 보정의 효과 (The Effect of Deformation Heat Compensation in the Hot Forging Analysis of SAF 2507 Stainless Steel)

  • 방원규;정재영;장영원
    • 소성∙가공
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    • 제10권3호
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    • pp.206-213
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    • 2001
  • Dynamic deformation of metallic materials mostly accompanies substantial amounts of deformation heat. Since the flow stress of deformation is sensitive to temperature, implication of heat due to plastic work is essential to the evaluation of constitutive relations. In this study, a series of compression tests were conducted for SAF 2507 super duplex stainless steel at various temperatures and strain rates. The accumulation of plastic work was calculated through numerical integration and converted into the elevation of temperature. Subsequent logarithmic interpolation deduced isothermal flow surfaces, which were primary input data of finite element analysis. Simple closed die forging process was analyzed and optimized with commercial FEM code applying both raw and calibrated material database. The effect of accounting deformation heat was more noticeable in high-speed forming process.

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해수 환경에서 듀플렉스 스테인리스강의 전기화학적 거동 및 캐비테이션 특성 (Electrochemical and Cavitation-Erosion Characteristics of Duplex Stainless Steels in Seawater Environment)

  • 허호성;김성종
    • Corrosion Science and Technology
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    • 제20권6호
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    • pp.466-474
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    • 2021
  • A wet type scrubber for merchant vessel uses super austenitic stainless steels with pitting resistance equivalent number (PREN) of 40 or higher for operation in a harsh corrosive environment. However, it is expensive due to a high nickel content. Thus, electrochemical behavior and cavitation erosion characteristics of UNS S32750 as an alternative material were investigated. Microstructure analysis revealed fractions of ferritic and austenitic phases of 48% and 52%, respectively, confirming the existence of ferritic matrix and austenitic island. Potentiodynamic polarization test revealed damage at the interface of the two phases because of galvanic corrosion due to different chemical compositions of ferritic and austenitic phases. After a cavitation test, a compressive residual stress was formed on the material surface due to impact pressure of cavity. Surface hardness was improved by water cavitation peening effect. Hardness value was the highest at 30 ㎛ amplitude. Scanning electron microscopy revealed wave patterns due to plastic deformation caused by impact pressure of the cavity. The depth of surface damage increased with amplitude. Cavitation test revealed larger damage caused by erosion in the ferritic phase due to brittle fracture derived from different strain rate sensitivity index of FCC and BCC structures.