• Title/Summary/Keyword: 수소지연파괴

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Hydrogen Delayed Fracture of Automotive Multi-Phase Sheet Steels by Hydrogen Charging Condition (수소주입에 따른 자동차용 복합조직강판의 지연파괴 거동)

  • Park, Jae-U;Gang, Gye-Myeong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2013.05a
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    • pp.87-87
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    • 2013
  • 복합조직강의 미세조직제어를 통한 자동차용 고강도 강판재의 개발이 주요 연구과제로 있다. 하지만 고강도화에 따라 수소에 의한 지연파괴의 문제점이 있어, 이를 규명하고 해결하기 위한 많은 연구가 함께 이루어지고 있다. 본 연구에서는 연구, 개발되고 있는 복합조직강 중 DP강과 TRIP강의 수소취성에 미치는 미세조직의 영향을 분석하고, 수소주입조건에 따른 수소취성 및 지연파괴 거동에 대하여 조사하고자 하였다. 이를 위해 음극전기분해법을 이용, 주입수소량을 달리하여 주입수소가 복합조직강의 지연파괴에 미치는 영향을 분석하였다. Hydrogen determinator를 통해 시편 내 수소량을 측정하였고, 소형펀치시험에 의한 기계적물성 변화를 조사하였다. 또한 파단부위의 넓이와 깊이를 비교측정하였고, 파단면을 SEM으로 관찰하여 수소지연파괴 거동을 평가하고자 하였다.

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Effect of an Increased Wall Thickness on Delayed Hydride Cracking in Zr-2.5Nb Pressure Tube (Zr-2.5Nb 중수로 압력관의 수소지연파괴에 미치는 압력관 두께의 영향)

  • Jeong, Yong-Hwan;Kim, Young-Suk
    • Nuclear Engineering and Technology
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    • v.27 no.2
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    • pp.226-233
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    • 1995
  • The wall thickness of a pressure tube is increased in order to reduce the probability of failure in a pressure tube of CANDU type reactor. It is presented here that the variation of wall thickness changes stress, hydrogen concentration and delayed hydride cracking in Zr-2.5Nb pressure tube. When the wall thickness is increased from 4.2 mm to 5.2 mm, the stress exerted on the tube and the deuterium taken up during operation are reduced by 19%. Further, the calculated allowable depth of the surface flaw over which delayed hydride cracking(DHC) is susceptible increases by 50%. DHC initiation is controlled by the stress and by the hydrogen concentration in the pressure tube. The results are therefore very significant in such a respect that increased wall thickness may reduce DHC initiation. Ac the wall thickness increases the hydrostatic tension will increase. Its impact on the acceleration of the crack growth rate of DHC deserves further studies.

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Hydrogen Effect Assessment of Fuel Supply Systems for Hydrogen Blended Natural Gas Vehicle (수소-천연가스 혼합연료 차량 연료 공급시스템 수소영향 평가)

  • Kang, SeungKyu;Kim, SangRyul
    • Journal of Energy Engineering
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    • v.26 no.4
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    • pp.1-6
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    • 2017
  • This study evaluated hydrogen effect of metal and non-metallic materials used in the hydrogen blended natural gas vehicle. Hydrogen penetrated concentration of 34Cr-Mo steel(850MPa tensile strength) for winter driving conditions was measured 0.0018ppm and summer driving conditions was 5.3ppm. The critical hydrogen concentration of high strength metal used in this study was measured 1.03ppm by CLT. Therefore, 34CrMo steel cas cause problems in the 30% HCNG(25MPa) environment. In case of the test for non-metallic materials, all materials met the criteria of the gas resistance test, but Fluorocarbon Rubber material had a significant change in the volume. So if it is used, extra care is needed.

A study of hydrogen embrittlement behavior in E.B welded 250,300 grade 18% Ni maraging steel (전자비임 용접한 250 및 300 Grade 18% Ni Maraging 강의 수소취화 거동에 관한 연구)

  • 윤한상;정병호
    • Journal of Welding and Joining
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    • v.5 no.2
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    • pp.53-59
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    • 1987
  • The effect of applied stress, current density and heat-treatment after welding on the time to fracture, fracture behavior was investigated by the method of constant load tensile testing under catholic charging with hydrogen in E.B. welded 250,300 Grade 18% Ni Maraging steel sheet. The main results obtained are as follows: 1. All specimen showed the characteristic delayed failure and the time to fracture showed decreasing tendency with the increase in current density and applied stress. 2. Hydrogen embitterment susceptibility of notched specimen after solution-treatment and aging after welding was more increased than that of aged smooth specimen and as welded specimen. 3. Fracture surface showed a typical intergranular fracture on the border, a dimple pattern in the center of specimen and some quasi-cleavage fracture between the intergranular and the dimple.

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Effects of Carbides on Hydrogen-induced Delayed Fracture for the Energy Saving Wire (ESW) (선조철강의 탄화물에 따른 수소지연파괴 거동 분석)

  • Lee, J.B.;Kang, N.H.;Park, J.T.;Ahn, S.T.;Park, Y.D.;Cho, K.M.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.139-141
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    • 2009
  • This study analyzed the effect of the microstructure and alloying element on hydrogen-induced delayed fracture properties for the Energy Saving Wire (ESW) developed recently. Specimens were produced with a diameter 6.5mm post to the deformation (0, 10, 20 and 30%), followed by injecting the hydrogen. The experimental results by using GAS chromatography showed that the more hydrogen was emitted for high-carbon steel (0.45%C steel and 0.35%C steel) than low-carbon steel(0.2%C-Cr steel and 0.2%C-Cr-Mo steel). And, 0.45%C steel, 0.35%C steel and 0.2%C-Cr-Mo steel exhibited the crack for 30% deformed specimen. The hydrogen emitted was analyzed with the amount, the spheroidization, and the size of the carbides.

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Sulfate Modulation for Hydrogen Production by Chlamydomonas reinhardtii in Continuous Culture (Chlamydomonas reinhardtii 연속 배양에서 수소생산을 위안 황 조절)

  • Kim, Jun-Pyo;Park, Tai-Hyun;Kim, Mi-Sun;Sim, Sang-Jun
    • KSBB Journal
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    • v.20 no.6
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    • pp.453-457
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    • 2005
  • We investigated the effect of sulfate re-addition on hydrogen production under sulfur-deprived condition. When the final concentration of sulfate to cell suspensions($0{\sim}120{\mu}M$) was increased, chlorophyll concentration, culture density, and total amount of $H_2$ produced, increased up to an optimal concentration of $30{\mu}M\;MgSO_4$. Maximum hydrogen volume was 236 mL $H_2/L$ culture at $30{\mu}M\;MgSO_4$. However, the addition of excess sulfate(above $MgSO_4\;60{\mu}M$) delayed the start of hydrogen production and the induction of hydrogenase. Accordingly, the final yield of hydrogen production was reduced. Using these results, we attempted the continuous and sustained hydrogen production by sulfate re-addition($30{\mu}M\;MgSO_4$) using a single C. reinhardtii culture for up to 4 cycles. In total, hydrogen production volume was 625 mL $H_2/L$ culture.