• Title/Summary/Keyword: 오스테나이트 304강

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A Study of Mechanical Properties for Austenite Stainless Steel of Cryogenic Liquied Nitrogen Storage Tank (초저온 액화질소 저장용기의 오스테나이트계 스테인리스강의 기계적 특성 연구)

  • Choi, Dong-Jun;Park, Hyung-Wook;Cho, Jong-Rae
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.4
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    • pp.451-459
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    • 2011
  • Austenitic stainless steels of 300 series are widely used as the structural material due to excellent their cryogenic mechanical properties at cryogenic temperature. There are 316 steel which molybdenum is added to improve the austenitic stability, 316L which carbon contents is reduced to decrease the grain boundary precipitation during welding process, and 316LN which nitrogen is added to improve the austenitic stability and the mechanical strength. But material researches for the welding conditions and mechanical properties at the cryogenic temperature were insufficient so far. In this paper, the characteristics of mechanical properties considering the effect of welding conditions and cryogenic temperature are studied.

Microstructure and Corrosion Characteristics of Austenitic 304 Stainless Steel Subjected to Long-term Aging Heat Treatment (장시간 시효 열처리된 오스테나이트계 304강의 미세조직과 부식 특성)

  • Huh, ChaeEul;Kim, ChungSeok
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.1
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    • pp.56-65
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    • 2022
  • The electrochemical corrosion properties of austenitic AISI 304 steel subjected to a long-term-aging heat treatment were investigated. AISI 304 steel was aged at 700 ℃ for up to 10,000 h. The variation in the microstructure of the aged specimens was observed by optical microscopy and scanning electron microscopy. Electrochemical polarization experiments were performed to obtain the corrosion current density (Icorr) and corrosion potential (Ecorr). Analyses indicated that the metastable intermetallic carbide M23C6 formed near the γ/γ grain boundary and coarsened with increasing aging time; meanwhile, the δ-ferrite decomposed into the σ phase and into M23C6 carbide. As the aging time increased, the current density increased, but the corrosion potential of the austenitic specimen remained high (at least 0.04 ㎛/cm2). Because intergranular carbide was absent, the austenitic annealed specimen exhibited the highest pitting resistance. Consequently, the corrosion resistance of austenitic AISI 304 steel decreased as the aging heat treatment time increased.

The Influence of Treatment Condition During Low Temperature Plasma Carburizing of AISI304L Stainless Steel (AISI304L 강에 저온 플라즈마침탄 처리 시 처리조건에 따른 표면특성평가)

  • Lee, In-Sup
    • Journal of Ocean Engineering and Technology
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    • v.25 no.1
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    • pp.56-60
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    • 2011
  • A low temperature plasma carburizing process was performed to AISI 304L austenitic stainless steel to achieve the enhancement of surface hardness without a compromise in their corrosion resistance. Attempts were made to investigate the influence of the processing temperatures on the surface-hardened layer during low temperature plasma carburizng in order to obtain the optimum processing conditions. The expanded austenite (${\gamma}C$) was formed on all the treated surfaces. Precipitates of chromium carbides were detected in the hardened layer (C-enriched layer) only for the specimen treated at $500^{\circ}C$. The hardened layer thickness of ${\gamma}C$ increased up to about $35\;{\mu}m$, with increasing treatment temperature. The surface hardness reached about 1000 $HK_{0.05}$, which is about 4 times higher than that of the untreated sample (250 $HK_{0.05}$). Minor loss in corrosion resistance was observed for the specimens treated at temperatures of $310^{\circ}C-450^{\circ}C$ compared with untreated austenitic stainless steel. Particularly, the precipitation of chromium carbides at $500^{\circ}C$ led to a significant decrease in the corrosion resistance.

An Experimental Study on Structural Behavior of Bolted Angle Connections with Austenitic Stainless Steel (오스테나이트계 스테인레스강(STS304) 앵글 볼트 접합부의 구조적 거동에 관한 실험적 연구)

  • Kim, Min-Seong;Kim, Tae-Soo;Kim, Seung-Hun;Lee, Yong-Taeg
    • Journal of Korean Society of Steel Construction
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    • v.23 no.1
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    • pp.29-39
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    • 2011
  • With regard to steel construction, many studies have been performed to examine the structural behavior of the bolted connections domestically and in other countries. Especially, a domestic study was conducted on the block shear fracture and shear lag effect on the single-bolted angle connection in carbon steel. In this study, specimens were prepared with the end distance parallel to the loading direction and bolt arrangement ($1{\times}1$, $1{\times}2$), as the main variables. Then the fracture mode and the curling effect on the bolted angle connection in austenitic stainless steel were investigated. Moreover, the fracture mode and ultimate strength were compared, and the strength reduction by curling was estimated.

A Study on the Corrosion Behavior of Austenitic Stainless Steel in Hot Molten Salt (오스테나이트 스테인레스강의 고온용융염 부식거동연구)

  • Jo, Su-Haeng;Park, Sang-Cheol;Jeong, Myeong-Su;Jang, Jun-Seon;Sin, Yeong-Jun
    • Korean Journal of Materials Research
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    • v.9 no.2
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    • pp.211-216
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    • 1999
  • Corrosion behavior of austenitic stainless steels of SUS 316L and SUS304L in molten salt of LiCl and $LiCl/Li_2O$ has been investigated in the temperature range of $650~850^{\circ}C$. Corrosion products of SUS316L and 304L in hot molten salt consisted of two layers-an outer layer of Li(CrFe)$O_2$and an inner layer of$Cr_2O_3$. The corrosion layer was uniform in molten salt of LiCl, but the intergranular corrosion occurred in addition to the uniform corrosion in mixed molten salt of LiCl/$Li_2O$. The corrosion rate increased slowly with the increase of temperature up to $750^{\circ}C$, but above $750^{\circ}C$ rapid increase in corrosion rate observed. SUS316L stainless steel showed slower corrosion rate than SUS 304L, exhibiting higher corrosion resistance in the molten salt.

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Effect of Cold Work on the Stress Corrosion Cracking in Austenitic 304 Stainless Steel (오스테나이트 304 스테인레스 강의 응력부식균열에 미치는 냉간가공의 영향)

  • 강계명;최종운
    • Journal of the Korean Society of Safety
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    • v.12 no.1
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    • pp.19-28
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    • 1997
  • This study was made of the effect of cold working on the stress corrosion cracking(SCC) of austenitlc 304 stainless steel in boiling 42% $MgCl_2$ solution. For this experiment, specimens cold-worked of 0%, 10%, 20%, 30%, 40% were fabricated respectively, and then experiments of mechanical properties and stress corrosion cracking(SCC) of these specimens were carried out. The results of these experiments indicate that the maximum resistance to SCC showed at 20% of cold working degree and that the SCC susceptibility depended on the volume fraction of deformation-induced martensite by cold working and the work hardening of matrix. On the other hand, the fracture mode was changed. This phenomenon was considered that deformation-induced martensite was grown from transgranular fracture mode to intergranular fracture mode and caused by increased of dislocation density along the slip planes.

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Dissimilar Metal Welding of Nd:YAG Laser of Austenitic Stainless Steel and Medium Carbon Steel (중탄소강과 오스테나이트계 스테인레스강의 Nd:YAG 레이저의이종금속 용접)

  • Shin H.J.;Yoo Y.T.;Ahn D.G.;Im K.;Shin B.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.1560-1565
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    • 2005
  • Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameters such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar plates, etc. The following conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.

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Dissimilar Metal Welding of Medium Carbon Steel and Austenitic Stainless Steel utilize CW Nd:YAG Laser (CW Nd:YAG 레이저를 이용한 중탄소강과 오스테나이트계 스테인레스강의 이종금속 용접)

  • Shin Ho-Jun;Ahn Dong-Gu;Im Kie-Gon;Shin Byung-Heon;Yoo Young-Tae
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.3 s.180
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    • pp.47-55
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    • 2006
  • Laser welding of dissimilar metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research is to investigate the influence of the process parameters, such as the welding for SM45C and STS304 with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the dissimilar welding, the welding quality of the cut section, stress-strain behavior and the hardness of the welded metal are investigated. From the results of the investigation, it has been shown that the optimal voiding condition without defects in the vicinity of the welded area and with a good welding quality is 1600W of the laser power, 0.85m/min of welding speed and $4{\ell}/min$ of pressure for shielding gas.

Hot Ductility Behavior and Hot Cracking Susceptibility of Type 303 Austenitic Stainless Steel(1) -Hot ductility Behavior- (303 오스테나이트계 스테인레스강의 고온연성거동과 고온균열감수성(I) -고온연성거동-)

  • ;;Lundin, C. D.
    • Journal of Welding and Joining
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    • v.6 no.1
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    • pp.35-45
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    • 1988
  • 오-스테나이트계 스테인레스강에 대한 용접은 용접재료의 개발과 더불어 각종 산업계에 널리 이용되고 있으며 최근 Type 303 오-스테나이트계 스테인레스강 등은 free machining재로써 널리 응용되고 있다. 그러나 이 303계는 피삭성, 절삭성, 칩형성개선을 위한 특수원소(Se, S 등)의 첨가 때문에 용접성에 문제점을 제기하고 있다. 본 연구에서는 Type 303을 중심으로 AISI 304-316NG 및 347NG계의 오-스테나이트계 스테인레스강의 고온연성거동과 고온균열감수성(용접성)에 관한 연구에 대한 검토중 고온연성거동에 관하여 조사하였다. 고온연성평가는 Gleeble Simulator에 의하여 재료와 방향성에 따라 검토하였으며, 그 결과 모든 재료는 압연방향을 종방으로 시험하였을 때는 거의 유사한 고온연성을 나타내었으나 횡방향으로 시험하였을 때는 종방향에 비하여 연성저하를 나타내었다. 이와 같은 고온연성은 후속연구에서 검토될 고온균열 감수성과 밀접한 관련성에 의하여 용접성을 평가할 수 있다.

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Effects on Machining on Surface Residual Stress of SA 508 and Austenitic Stainless Steel (SA508 탄소강 및 오스테나이트 스테인리스강의 표면잔류응력에 미치는 기계가공효과)

  • Lee, Kyoung-Soo;Lee, Seong-Ho;Park, Chi-Yong;Yang, Jun-Seok;Lee, Jeong-Geun;Park, Jai-Hak
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.5
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    • pp.543-547
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    • 2011
  • Primary water stress corrosion cracking has occurred in dissimilar weld areas in nuclear power plants. Residual stress is a driving force in the crack. Residual stress may be generated by weld or surface machining. Residual stress due to surface machining depends on the machining method, e.g., milling, grinding, or EDM. The stress is usually distributed on or near the surface of the material. We present the measured residual stress for machining on SA 508 and austenitic stainless steels such as TP304 and F316. The residual stress can be tensile or compressive depending on the machining method. The depth and the magnitude of the residual stress depend on the material and the machining method.