• 한국분말재료학회지
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• 제28권2호
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• pp.110-119
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• 2021

In this study, the high-temperature oxidation properties of austenitic 316L stainless steel manufactured by laser powder bed fusion (LPBF) is investigated and compared with conventional 316L manufactured by hot rolling (HR). The initial microstructure of LPBF-SS316L exhibits a molten pool ~100 ㎛ in size and grains grown along the building direction. Isotropic grains (~35 ㎛) are detected in the HR-SS316L. In high-temperature oxidation tests performed at 700℃ and 900℃, LPBF-SS316L demonstrates slightly superior high-temperature oxidation resistance compared to HR-SS316L. After the initial oxidation at 700℃, shown as an increase in weight, almost no further oxidation is observed for both materials. At 900℃, the oxidation weight displays a parabolic trend and both materials exhibit similar behavior. However, at 1100℃, LPBF-SS316L oxidizes in a parabolic manner, but HR-SS316L shows a breakaway oxidation behavior. The oxide layers of LPBF-SS316L and HR-SS316L are mainly composed of Cr₂O₃, Fe-based oxides, and spinel phases. In LPBF-SS316L, a uniform Cr depletion region is observed, whereas a Cr depletion region appears at the grain boundary in HR-SS316L. It is evident from the results that the microstructure and the high-temperature oxidation characteristics and behavior are related.

• 대한기계학회논문집
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• 제13권6호
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• pp.1193-1202
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• 1989

본 논문에서는 발전소의 소재로 많이 쓰이고 있는 304 스테인리스강(앞으로는 304SS로 표기함)과 316스테인리스강(앞으로는 316SS로 표기함)의 크립 균열 발생 거동 을 각각 600.deg. C와 625.deg. C에서 조사한다. 이 온도는 발전소의 반응기(reactor)에 사용 되는 304SS와 316SS이 받는 온도이다. 즉 304SS와 316SS의 크립 균열 발생을 지배 하는 파괴 매개변수가 무엇인지가 크립 파괴 실험을 통하여 조사된다. 실험 결과는 이미 제안되어 있는 크립 균열 발생 모델에서 예측된 결과와 비교된다. 특히 304SS 와 316SS은 고온에서의 연성도가 변형률 속도에 따라 변하는 것으로 알려져 있다. 본 연구에서는 '변형률 속도에 따른 재료의 연성도의 변화에 근거한 균열 발생 모델' 을 제안하고, 그 모델에서 예측된 크립 발생 거동을 실험 결과와 비교한다.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.479-489
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• 2019

Low-cycle fatigue (LCF) tests were performed for Alloy 690 and 316 SS in a simulated pressurized water reactor (PWR) environment. Alloy 690 showed about twice longer LCF life than 316 SS at the test condition of 0.4% amplitude at strain rate of 0.004%/s. Observation of the oxide layers formed on the fatigue crack surface showed that Cr and Ni rich oxide was formed for Alloy 690, while Fe and Cr rich oxide for 316 SS as an inner layer. Electrochemical analysis revealed that the oxide layers formed on the LCF crack surface of Alloy 690 had higher impedance and less defect density than those of 316 SS, which resulted in longer LCF life of Alloy 690 than 316 SS in a simulated PWR environment.

• 대한조선학회논문집
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• 제34권3호
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• pp.61-69
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• 1997

CT 시험편을 사용하여 평면응력 파괴인성치를 산정하는 간단하고 새로운 방법론을 제안하였다. 평면응력 조건하의 균열선단에서 발생하는 좌굴을 방지하는 판을 부착하여 SS304와 SS316의 평면응력 파괴인성치를 정확하게 결정하였다. SS304와 SS316의 피로균열 전파거동이 피로하중 주파수에 미치는 영향을 영상해석법(LAT)을 사용하여 규명하였다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 추계학술대회
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• pp.175-177
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• 1994

The wear corrosion behaviour of a nitrogen ion implanted super stainless steel (S.S.S, 22Cr - 20Ni - 6Mo - 0.25N) was compared with those of S.S.S, 316L SS and TiN coated 316L SS. The Cr and Ni amounts won out from the materials were investigated using an electrothermal atomic absorption spectrometry. We observed that the Cr dissolution rate of the S.S.S was similar to that of 316L SS, however, the Ni release of the S.S.S was feater than 316L SS. The metal ions released from the nitrogen ion implanted S.S.S surface were significantly reduced. The wear corrosion behaviour of the stainless steels was not correlated with the results shown by a static metal ion release test.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2001년도 연료전지심포지움 2001논문집
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• pp.237-242
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• 2001

용융탄산염 연료전지에서 분리판으로 사용되는 316L 스테인리스 스틸의 내식성을 향상시키기 위해 Ni과 Al을 전기도금법에 의해 코팅하였으며 열처리를 통해 스테인리스 스틸표면에 $Ni_2Al_3$, NiAl 등의 금속간화합물을 형성시켰다. $62mol\%Li_2CO_3-38mol\%K_2CO_3$ 전해질 내에서 100시간 동안 침지실험을 수행한 결과 Al의 도금두께가 $10{\mu}m$ 이상인 경우에는 내식성이 상당히 향상되었음을 확인하였다.

• Journal of Welding and Joining
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• 제20권2호
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• pp.109-115
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• 2002

In the case of using high temperature by coating ceramic/metal, large stress was produced due to difference of thermal expansion coefficient between those. And then lead to delamination. In order to relaxation of the stress A1$_2$O$_3$/SS316 composite powders with $10wt.%Al_2O_3$ compositional gradient and $10wt.%Al_2O_3$ agglomerated powder were made by spray drying method. These powders were sintered to improve the strength and to be plasma sprayed in order to fabricate the FGC(functionally graded coating). The influence of gun power, working distance and Ar pressure on the microstructure of the coating layer was studied in order to optimize the plasma spray conditions. It was proven that the optimum conditions were 40kw gun power, 5cm working distance and $100ft^3/h$ Ar flow for both powders. FGC with 10 compositional steps was fabricated and the total thickness was 1.3mm. FGC was heat treated at $1100^{\circ}C$for 10hours to evaluate the heat resisting characteristics.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.295-298
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• 2005

A minimum commitment method (MCM) was applied to predict the creep rupture life of type 316LN SS. For this purpose, a number of the creep rupture data for the type 316LN SS were collected through literature survey and experimental data of KAERl, Using the short-term creep rupture data under 2000 hr, the long-term creep rupture life above $10^5$ hour was predicted by means of the MCM. An optimum value of A, P and G function, used in the MCM equation, was determined respectively, and the creep rupture life with the A values in different temperatures was compared with the experimental data and the predicted curves.

• 한국진공학회지
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• 제15권3호
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• pp.325-330
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• 2006

ITER (International Thermonuclear Experimental Reactor) 조달용 일차벽의 제조 건전성을 검증하기 위해서, 일차벽을 구성하는 Cu/SS mock-up을 제작하여 고열부하 시험을 수행하였다. Cu/SS mock-up은 CuCrZr과 SS316L이 사용되었으며, 두 금속은 $1050^{\circ}C$, 150 MPa의 조건에서 고온등방가압법 (HIP, Hot Isostatic Pressing) 과정을 통해 접합되었다. 시험에 사용된 고열부하 장치는 일본 원자력연구소의 JEBIS (JAEA Electron Beam Irradiation Stand)를 이용하였으며, 시험 조건은 FEM 코드인 ANSYS 해석을 통해 결정하였다. 시험은 $5MW/m^2$의 고열부하를 15초간 인가하고, 30초간 냉각하는 방법으로 수행되었으며, 시험 종료 후 얻어진 시험결과와 해석결과가 잘 일치함을 확인하였다.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2131-2140
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• 2024

The chloride-induced stress corrosion cracking (CISCC) is one of the major integrity concerns in dry storage canisters made of austenitic stainless steels (ASSs). In this study, an advanced duplex stainless steel (DSS) with a composition of Fe-19Cr-4Ni-2.5Mo-4.5Mn (ADCS) was developed and its performance was compared with that of commercial ASS and DSS alloys. The chemical composition of ADCS was determined to obtain greater pitting and CISCC resistance as well as a proper combination of strength and ductility. Then, the thermomechanical processing (TMP) condition was applied, which resulted in higher strength than ASSs (304L SS and 316L SS) and better ductility than DSSs (2101 LDSS and 2205 DSS). The potentiodynamic polarization and electrochemical impedance spectra (EIS) results represented the better pitting corrosion resistance of ADCS compared to 304L SS and 316L SS by forming a better passive layer. The CISCC tests using four-point loaded specimens showed that cracks were initiated at 24 h for 304L SS and 144 h for 316L SS, while crack was not found until 1008 h for ADCS. Overall, the developed alloy, ADCS, showed better combination of CISCC resistance and mechanical properties as dry storage canister materials than commercial alloys.