• Title/Summary/Keyword: Austenitic stainless steel

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A Basic Study on the Defect Detectability of Austenitic Stainless Steel Weldments using Ultrasonic Testing (초음파를 이용한 Austenitic Stainless Steel 용접부의 결함검출에 관한 기초적 연구)

  • Park, M.H.;Park, K.H.;Seo, D.M.;Yoon, K.S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.9 no.1
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    • pp.8-21
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    • 1989
  • This paper presents the ultrasonic characteristics of weldment and detectability of defects of weldment in Austenitic Stainless Steel Type 304 that is composed of mostly coolant piping system in nuclear power plants. The results of this experient show as follows: 1. When the ultrasonic beam detects the defects on the side of base metal and on the opposite side of weldment, the indications which was detected on the screen show different amplitude and different metal path each. 2. The ultrasonically estimated notch depth is generally oversized than actual notch depth. 3. It is easy for the false indication to show up on the screen because of columnar structure of weldment in austenitic stainless steel. 4. The higher frequencies of transducer have more difficulties to detect the defects of the opposite side of weldment because of ultrasonic attenuation in weldment and the longitudinal transmitter-receiver transducer is the most effective in detecting the opposite side defects of weldment.

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Evaluation of Material Properties Considering Thermal Embrittlement for Accelerated aged CF-8M and CF-8A Cast Austenitic Stainless Steel (가속열화된 CF-8M 및 CF-8A 주조 스테인리스강의 열취화 재료물성치 평가)

  • Kim, Cheol;Park, Heung-Bae;Jin, Tae-Eun;Jeong, Ill-Seok
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.118-123
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    • 2004
  • Cast austenitic stainless steel have been widely used for primary coolant piping in light water reactors. This material is subject to thermal embrittlement at reactor operating temperature. CF-8M and CF-8A cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. Thermal embrittlement results in spinodal decomposition of delta-ferrite leading to decreased fracture toughness. In this study, the specimens were prepared using an accelerated aging method. The measurement of ferrite content, Charpy impact test and J-R test were performed to verify the predicting equation for aged material properties. In case of above 25% ferrite content, predicted result of J-R curve might be non-conservative.

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Evaluation of Material Properties due to Thermal Embrittlement in CF8M Cast Austenitic Stainless Steel (CF8M 주조 오스테나이트 스테인리스강의 열취화에 따른 재료물성치 평가)

  • Kim, C.;Park, H.B.;Jin, T.E.;Jeong, I.S.;Seok, C.S.;Park, J.S.
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.131-136
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    • 2003
  • CF8M cast austenitic stainless steel is used for several components such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. In this study, three kinds of the aged CF8M specimen were prepared using an artificially simulated aging method. The objective of this study is to summarize the method of estimating ferrite contents, Charpy impact energy and J-R curve, and to evaluate the thermal embrittlement of the CF8M cast austenitic stainless steel piping used in the domestic nuclear power plants.

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The Study on Evaluation of Weldability of Austenitic Heat Resistant Stainless Steel (오스테나이트계 내열 스테인리스강의 용접성 평가에 관한 연구)

  • 변경일;지병하;정호신
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2000.10a
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    • pp.236-239
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    • 2000
  • It is important to evaluate austenitic heat resistant stainless steel because of low weldability of austenitic heat resistant stainless steel containing high Si. This study took varestraint test for evaluation of solidification cracking sensitivity and Erichsen test for evaluation of weld metal ductility. As a result of tests, solidification crack sensitivity increased with adding $N_2$ to shielding gas, and W had detrimental effect on crack resistance, but Ce had beneficial effect on crack resistance. Under same heat input, ductility of weld metal increased with welding speed.

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Evaluation of Thermal Embrittlement for Cast Austenitic Stainless Steel Piping in PWR Nuclear Power Plants (PWR 원전 주조 스테인리스강 배관의 열취화 평가)

  • Kim, Cheol;Jin, Tae-Eun
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.96-101
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    • 2004
  • Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal embrittlement at the reactor operating temperature. The objective of this study is to summarize the method of estimating ferrite content, Charpy impact energy and J-R curve and to evaluate the thermal embrittlement of the cast austenitic stainless steel piping used in the domestic nuclear power plants. The result of evaluation, two domestic nuclear power plants used CF-8M and CF-8A material has adequate fracture toughness after saturation.

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Cold-formed austenitic stainless steel SHS brace members under cyclic loading: Finite element modelling, design considerations

  • YongHyun Cho;Fangying Wang;TaeSoo Kim
    • Steel and Composite Structures
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    • v.47 no.1
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    • pp.135-145
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    • 2023
  • This study presents a numerical investigation into the hysteretic behavior of cold-formed austenitic stainless steel square hollow section (SHS) brace members using a commercial finite element (FE) analysis software ABAQUS/Standard. The initial/post buckling and fracture life of SHS brace members are comprehensively investigated through parametric studies with FE models incorporating ductile fracture model, which is validated against the existing laboratory test results collected from the literature. It is found that the current predictive models are applicable for the initial buckling strengths of SHS brace members under cyclic loading, while result in significant inaccuracy in predictions for the post-buckling strength and fracture life. The modified predictive model is therefore proposed and the applicability was then confirmed through excellent comparisons with test results for cold-formed austenitic stainless SHS brace members.

Effects of annealing temperature on strain-induced martensite and mechanical properties of 304 stainless steel (304 스테인리스 강의 가공유기 마르텐사이트와 기계적 거동에 미치는 온도의 영향)

  • Lee, S.H.;Choi, C.Y.;Nam, W.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.203-206
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    • 2008
  • Transformation of austenite to martensite during cold rolling has been widely used to strengthen metastable austenitic stainless steel grades. Aging treatment of cold worked metastable austenitic stainless steels, including ${\alpha}'$-martensite phase, results in the further increase of strength, when aging is performed in $200^{\circ}C$ to $450^{\circ}C$ temperature range. The purpose of the present study was to evaluate the effect of time and temperature on the stress-strain behavior of cold worked austenitic stainless steels. The amount of ${\alpha}'$-martensite during cold working and aging was examined by ferrite scope and X-ray diffraction (XRD). During aging at $450^{\circ}C$ for 1hr, tensile strength dramatically increased by 150MPa. Deformed metastable austenitic steels containing the "body-centered" ${\alpha}'$-martensite are strengthened by the diffusion of interstitial solute atoms during aging at low temperature.

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Stress Corrosion Cracking Behavior of Cold Worked 316L Stainless Steel in Chloride Environment

  • Pak, Sung Joon;Ju, Heongkyu
    • Journal of Korea Foundry Society
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    • v.40 no.5
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    • pp.129-133
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    • 2020
  • The outcomes of solution annealing and stress corrosion cracking in cold-worked 316L austenitic stainless steel have been studied using x-ray diffraction (XRD) and the slow strain rate test (SSRT) technique. The good compatibility with a high-temperature water environment allows 316L austenitic stainless steel to be widely adopted as an internal structural material in light water reactors. However, stress corrosion cracking (SCC) has recently been highlighted in the stainless steels used in commercial pressurized water reactor (PWR) plants. In this paper, SCC and inter granular cracking (IGC) are discussed on the basis of solution annealing in a chloride environment. It was found that the martensitic contents of cold-worked 316L stainless steel decreased as the solution annealing time was increased at a high temperature. Moreover, mode of SCC was closely related to use of a chloride environment. The results here provide evidence of the vital role of a chloride environment during the SCC of cold-worked 316L.

Enhancement of Surface Hardness and Corrosion Resistance of AISI 310 Austenitic Stainless Steel by Low Temperature Plasma Carburizing Treatment

  • Lee, Insup
    • Journal of the Korean institute of surface engineering
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    • v.50 no.4
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    • pp.272-276
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    • 2017
  • The response of AISI 310 type austenitic stainless steel to the novel low temperature plasma carburizing process has been investigated in this work. This grade of stainless steel shows better corrosion resistance and high temperature oxidation resistance due to its high chromium and nickel content. In this experiment, plasma carburizing was performed on AISI 310 stainless steel in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-Ar-CH_4$ gas mixtures. The working pressure was 4 Torr (533Pa approx.) and the applied voltage was 600 V during the plasma carburizing treatment. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. The phase of carburized layer formed on the surface was confirmed by X-ray diffraction. The resultant carburized layer was found to be precipitation free and resulted in significantly improved hardness and corrosion resistance.

The Effect of Weld Metal Copper Content on HAZ Cracking in Austenitic Stainless Steel welded with Al-brass

  • Lee, H.W.;Lee, J.S.;Choe, W.H.
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.152-154
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    • 2005
  • Austenitic stainless steel has good weldability but is sensitive to hot cracking such as solidification crack and liquation crack. In this study, the specimens of dissimilar metals made between austenitic stainless steel and Al-brass were welded by GTAW process using four different filler metals. Cracks were detected in the heat-affected zone of the stainless steel when welded with CuAl, CuSn and NiCu filler metals, but no cracks were detected a Ni filler metal was used. The cracks propagated along the grain boundary in the heat affected zone near the fusion line to base metal of 316L stainless steel. The cracks were located inside the weld bead with very fine hairline crack. All cracks initiated at the fusion line and moved forward in the base metal. From energy dispersion spectroscopy (EDS), Cu peak was detected only in the crack-opening area.

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