• Journal of Advanced Marine Engineering and Technology
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• 제15권4호
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• pp.22-28
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• 1991

The crevice corrosion behavior on austenitic AISI 304 and 316L stainless steel welded by TIG, MIG, $CO_2$ and SMA was studied. The results are as follows : In 10% $FeCl_3$ solution and natural sea water sampled near Mokpo port, the base metal of 304 stainless steel showed small amount corrosion, whereas 316L stainless steel did not showed any corrosion in the test periods. The weight loss caused by crevice corrosion increased with increasing weld heat input and residual .delta. ferrite formed in welded part. The corrosion resistance of the welded part was in the order of TIG, MIG, $CO_2$ and SMA. From this tendency, it is proved that the smaller heat input gives the better corrosion resistance.

• 한국추진공학회지
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• 제12권5호
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• pp.35-42
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• 2008

본 연구는 AISI 304강의 상온 및 고온 인장실험을 수행한 결과이다. 항공구조재료로 널리 사용되고 있는 AISI 304강의 인장실험을 ASTM 규정에 따라 상온 및 고온에서 수행하였다. A Basis와 B Basis 인장강도를 평가하기 위하여 정규확률지를 사용하였다. 응력과 소성변형률과의 관계를 지수함수로 가정하는 Ramberg-Osgood 파라미터는 시험데이터의 최소제곱추정을 이용하여 구하였다. 인장실험 후 시험편의 표면을 SEM 영상과 EDX를 사용하여 관찰하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 춘계학술발표대회 개요집
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• pp.134-137
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• 1999

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.137-146
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• 2008

Nd:YAG pulse laser welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Due to geometric symmetry, a half model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of butt welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• 대한기계학회논문집A
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• 제31권8호
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• pp.839-846
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• 2007

Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.153-154
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• 2007

AISI316L강은 AISI304L강과 기본 조성은 같지만 316L강이 약 2.5%의 Mo가 첨가되어 있다. 저온 플라즈마 질탄화 시 모재에 첨가된 Mo의 영향을 조사하기 위하여 처리온도를 변화시켜 실험하였다. 같은 처리온도의 경우 경화층의 두께는 316L강이 비교적 두껍게 형성되었다. 316L강의 경우 $450^{\circ}C$이하에서 약 25 ${\mu}m$까지 형성되었고, 306L강의 경우 $400^{\circ}C$에서 약 10 ${\mu}m$까지 형성되었다. $400^{\circ}C$ 이하에서 경화층은 두 가지시편 모두 확장된 오스테나이트 (${\gamma}_N,\;{\gamma}_c$)로 이루어져 있으나, 304L의 경우 $430^{\circ}C$부터 석출물(CrN)이 형성되기 시작하였다. 316L의 경우 $450^{\circ}C$까지 석출물이 형성되지 않았고, $480^{\circ}C$에서 석출물 (CrN)이 관찰되었다. 석출물이 형성된 시편을 제외한 모든 시편의 내식성은 모제보다 증가 하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권7호
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• pp.872-878
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• 2003

As the results of recent industrial development, many industrial plants and marine structures are exposed to severe corrosion environment than before. Especially, under the wet environment, crevice corrosion damage problems necessarily occur and encourage many interests to prevent them. In this study, the electrochemical polarization test was carried out to study characteristics of crevice corrosion for AISI 304 stainless steel in various solution temperatures. The results are as follows ; 1) as the solution temperature increased in IN $\textrm{H}_2\textrm{SO}_4$, the passive current density and critical current density were increased, whereas corrosion potential and break down potential were nearly constant, 2) as the solution temperature increased. the induced time for initiation of crevice corrosion was shortened. 3) The potential range in the crevice was -220mV/SCE to -380mV/SCE according to the distance from the crevice opening, which is lower than that of external surface of -200mV/SCE.

• 한국표면공학회지
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• 제37권1호
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• pp.53-57
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• 2004

Austenitic stainless steel AISI 304 was nitrided in a low-pressure RF plasma using pure nitrogen. With a treatment of time of 4.0h at $400^{\circ}C$, the nitrogen-rich layer on the sample was $3\mu\textrm{m}$thick and had a hardness of approximately 4.4 times higher than that of untreated material. XRD data showed that as the process temperature rose from 350∼$450^{\circ}C$, the expanded austenite peaks became more prominent while the austenite peaks became weaker. Expanded austenite was transformed to ferrite and CrN at the treatment of$ 500^{\circ}C$. Langmuir probe measurements showed that electron density decreased above $450^{\circ}C$.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.293-296
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• 2001

The dynamic softening mechanisms of AISI 316, AISI 304 and AISI 430 stainless steels were studied with torsion test in the temperature range of $900 - 1200^{\circ}C$ and the strain rate range of $5.0x10^{-2}-5.0x10^0/sec$. The austenitic stainless steels, such as AISI 316 and AISI 304 were softened by dynamic recrystallization (DRX) during hot deformation. Also, the evolutions of flow stress and microstructure of AISI 430 ferritic stainless steel show the characteristics of continuous dynamic recrystallization (CDRX). To establish the quantitative equations for DRX of AISI 316 stainless steel, the evolution of flow stress curve with strain was analyzed. The critical strain (${\varepsilon}_c$) and strain for maximum softening rate (${\varepsilon}^{*}$) could be confirmed by the analysis of work hardening rate ($d{\sigma}/d{\varepsilon}={\theta}$). The volume fraction of dynamic recrystallization ($X_{DRX}$) as a function of processing variables, such as strain rate ( $\varepsilon$ ), temperature (T), and strain ( $\varepsilon$ ) were established using the ${\epsilon}_c$ and ${\varepsilon}^{*}$. For the exact prediction the ${\varepsilon}_c,\;{\varepsilon}^{*}$ and Avrami' exponent (m') were quantitatively expressed by dimensionless parameter, Z/A, respectively. It was found that the calculated results were agreed with the experimental data for the steels at my deformation conditions. Also, we can reasonably conclude that the DRX, CDRX and grain refinement of stainless steels can be achieved by large strain deformation at high Z parameter condition.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 춘계학술발표회 초록집
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• pp.118-119
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• 2007

오스테나이트계 스테인리스 AISI304L강을 저온 플라즈마 분위기에서 표면에 C와 N을 주입하면 내식성의 저하 없이 표면경도를 증가 시킬 수 있다. 이 공정에서 온도에 따른 영향을 조사하기위해 $380^{\circ}C{\sim}430^{\circ}C$의 온도 범위에서 20시간 동안 실시하였다. 경화층의 두께는 $7{\sim}16\;{\mu}m$정도였으며, N의 농도가 높은 영역과 C의 농도가 높은 영역으로 나뉘어 형성되었고, N이 풍부한 영역이 표면층에 형성되고 그 아래에 C의 농도 높은 영역이 형성되었다. 표면층은 질소에 의해 확장된 오스테나이트(${\gamma}_N$)상을 가지며 고온에서 처리한 경우 석출물이 형성되었다. 표면경도는 약 $900\;HV_{0.01}{\sim}1200\;HV_{0.01}$로 측정되었다.