• Title/Summary/Keyword: Superaustenitic Stainless Steel

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An Nondestructive Evaluation of Degraded Damage for Superaustenitic Stainless Steel (슈퍼 오스테나이트 스테인리스강의 열화손상에 대한 비파괴적 평가)

  • Kwon, Il-Hyun;Baek, Seung-Se;Iino, Y.;Yu, Hyo-Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1332-1339
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    • 2002
  • This research was undertaken to clarify effects of thermal aging on electrochemical and mechanical properties of superaustenitic stainless steel and to detect the material degradation nondestructively. The steel was artificially aged at $300{\sim}650^{\circ}C$ for $240{\sim}10,000h$ and the mechanical properties were investigated at $-196{\sim}650^{\circ}C$ using small punch(SP) test. Also, the change in electrochemical properties caused by effects of thermal aging on superaustenitic stainless steel was investigated using electrochemical anodic polarization test in a KOH electrolyte. Carbides and ${\eta}-phase(Fe_2Mo)$ precipitated in the grain boundaries seem to deteriorate the mechanical properties by decreasing cohesive strength in the grain boundaries and to promote the current density observed in electrochemical polarization curves, The electrochemical and mechanical properties of superaustenitic stainless steel decreased significantly in the specimen aged at $650^{\circ}C$ corresponding to the sensitization temperature for conventional austenitic stainless steels.

An Evaluation of Degraded Damage for Superaustenitic Stainless Steel by Electrochemical Polarization Technique (전기화학기법에 의한 슈퍼 오스테나이트 스테인리스강의 열화손상 평가)

  • Kwon, Il-Hyun;Lee, Song-In;Baek, Seung-Se;Lee, Jong-Gi;Iino, Y.;Yu, Hyo-Sun
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.143-148
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    • 2001
  • This research was undertaken to clarify effects of thermal aging on electrochemical and mechanical properties of superaustenitic stainless steel. The steel was artificially aged at $300{\sim}650^{\circ}C$ for $240{\sim}10,000hrs$. and investigated at $-196{\sim}650^{\circ}C$ using small punch(SP) test. Also, the change in electrochemical properties caused by effects of thermal aging was investigated using electrochemical anodic polarization test in a KOH electrolyte. Carbides and ${\eta}-phase(Fe_2Mo)$ precipitated in the grain bounderies seem to deteriorate the mechanical properties by decreasing cohesive strength in the grain bounderies and promote the current density observed in electrochemical polarization curves. The electrochemical and mechanical properties of superaustenitic stainless steel was drastically decreased in the specimen aged at $650^{\circ}C$.

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Electrochemical Characteristics of Superaustenitic Stainless Steel with Temperature in Sea Water (슈퍼오스테나이트 스테인리스강의 해수환경에서 온도에 따른 전기화학적 특성)

  • Hwang, Hyun-Kyu;Kim, Seong-Jong
    • Corrosion Science and Technology
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    • v.20 no.6
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    • pp.391-402
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    • 2021
  • In this investigation, the electrochemical characteristics of superaustenitic and general austenitic stainless steels were compared by conducting potentiodynamic polarization experiment with varying temperatures in natural seawater solution. From the result of the potentiodynamic polarization experiment, the corrosion rate of UNS S31603 was found to be 17 times faster than that of UNS N08367 under the most severe corrosion conditions. The relationship between the corrosion rate by maximum damage depth and the corrosion rate by the corrosion current density was expressed as α value for each stainless steel. The α value of UNS S31603 under all temperature conditions was higher than that of UNS N08367 under similar conditions. This means that UNS S31603 is more prone to localized corrosion than UNS N08367. UNS S31603 expressed pitting type damages under all temperature conditions as shown by SEM analysis results. The pitting damage rapidly grew at the relatively poor grain boundaries. Damage on UNS N08367 was not clearly represented at 30 ℃ and 60 ℃, and slight intergranular corrosion damage was observed on the entire surface at 90 ℃.