• Journal of the Korean Electrochemical Society
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• v.5 no.2
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• pp.62-67
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• 2002

The corrosion of the metallic cell components is blown to be one of the major reason f3r the performance degradation and subsequently the life-time limitation of the MCFC. To elucidate the corrosion phenomena, a corrosion study with the AISI-type 316L stainless steel, the most widely used separator material, in 621Li/38K carbonate eutectic melt was carried out. Corrosion phenomena in an MCFC were observed to differ from one location to another due to different environmental condition. The stability of passive film was found to be responsible fur the variations in corrosion phenomena. According to the potentiodynamic analysis, the passive film formed in anode-gas environment was less stable than in cathode-gas environment. The potentiostatic method combined with XRD analysis in addition to the cyclicvoltammetry was conducted to get an insight on variety corrosion reaction of AISI-type 316L stainless steel in a carbonate melt.

• Korean Journal of Metals and Materials
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• v.49 no.7
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• pp.515-521
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• 2011

Small punch creep testing has received attention due to the convenience of using smaller specimens than those of conventional uniaxial creep tests, which enables creep testing on developing or currently operational components. However, precedent studies have shown that it is necessary to consider friction between the punch and specimen when computing uniaxial equivalent stress from a finite element model. In this study, small punch creep behaviors of AISI 316L stainless steel, which is widely used in high temperature-high pressure machineries, have been compared for the two different ceramic balls such as $Si_3N_4$ and $Al_2O_3$. The optimal range of the friction coefficient is 0.4~0.5 at $650^{\circ}C$ for the best fit between experimental and simulation data of AISI 316 L stainless steel. The higher the friction coefficient, the longer the creep rupture time is. Therefore, the type of ceramic ball used must be specified for standardization of small punch creep testing.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.4
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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.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.6
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• pp.315-322
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• 2021

In this study, we investigate the variation in microstruture and mechanical property of austenitic 316L stainless steel during long-term material degradation. To simulate the material degradation, the AISI 316 steel was exposed to accelerate under a temperature of 600℃ for up to 10000 hours at each predetermined heat treatment time. As the long-term material degradation time increase, the grain shape was changed from polygonal grains with annealing twins to circular grains. Most twins distributed uniformly interior of grains are recovered and disappered with long-term material degradation. Also, the δ ferrite along grain boundaries decomposed and transformed into the σ phase resulting in decrease of elongation of austenitic 316L stainless steel.

• Journal of the Korean institute of surface engineering
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• v.48 no.6
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• pp.269-274
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• 2015

In this experiment, post-nitriding treatment was performed at $400^{\circ}C$ on AISI 316 stainless steel which was plasma carburized previously at $430^{\circ}C$ for 15 hours. Plasma nitriding was implemented on AISI 316 stainless steel at various gas compositions (25% $N_2$, 50% $N_2$ and 75% $N_2$) for 4 hours. Additionally, during post nitriding Ar gas was used with $H_2$ and $N_2$ to observe the improvement of surface properties. After treatment, the behavior of the hybrid layer was investigated by optical microscopy, X-ray diffraction, and micro-hardness testing. Potentiodynamic polarization test was also used to evaluate the corrosion resistance of the samples. Meanwhile, it was found that the surface hardness increased with increasing the nitrogen gas content. Also small percentage of Ar gas was introduced in the post nitriding process which improved the hardness of the hardened layer but reduced the corrosion resistance compared with the carburized sample. The experiment revealed that AISI 316L stainless steel showed better hardness and excellent corrosion resistance compared with the carburized sample, when 75% $N_2$ gas was used during the post nitriding treatment. Also addition of Ar gas during post nitriding treatment degraded the corrosion resistance of the sample compared with the carburized sample.

• Journal of the Korean Electrochemical Society
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• v.27 no.1
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• pp.8-14
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• 2024

Austenitic stainless steel 316L has been used a lot of applications because of its high corrosion resistance and formability. In addition, copper brazing is employed to create complex shape of 316L stainless steel for various engineering parts. In such system, copper-based filler metals make galvanic cell at metal/filler metal interface, and it accelerates corrosion of stainless steel. Furthermore, Cu-rich region formed by diffused copper in austenitic stainless steel can promote a pitting corrosion. In this study, we used an ammonia (NH₃) gas to nitride the 316L stainless steel for improving the corrosion resistance. The thickness of the nitride (nitrogen high) layer increased with the treatment temperature, and the surface hardness also increased. The potentiodynamic polarization test showed the improvement of corrosion resistance of 316L stainless steel by enhancing the passivation on nitride layer. However, in case of high temperature nitriding, a chromium nitride was formed and its fraction increased, so that the corrosion resistance was decreased compared to the intact 316L stainless steel.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.177-178
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• 2012

In this experiment, post-nitriding treatment has been performed at $400^{\circ}C$ on AISI 316 stainless steel which is plasma carburized previously at $430^{\circ}C$ for 15 hours. Plasma nitriding was implemented on AISI 316 stainless steel at various gas compositions (25% N2, 50% N2 and 75% N2) for 4 hours. Additionally, during post nitriding Ar gas was used with H2 and N2 to observe the improvement of treatment. After treatment, the behavior of the hybrid layer was investigated by optical microscopy, X-ray diffraction, and micro-hardness testing. Potentiodynamic polarization test was also used to evaluate the corrosion resistance of the samples. Meanwhile, it was found that the surface hardness increased with increasing the nitrogen gas content. Also small percentage of Ar gas was introduced in the post nitriding process which improved the hardness of the hardened layer but reduces the corrosion resistance compared with the carburized sample. The experiment revealed that AISI 316L stainless steel showed better hardness and excellent corrosion resistance compared with the carburized sample, when 75% N2 gas was used during the post nitriding treatment. Also addition of Ar gas during post nitriding treatment were degraded the corrosion resistance of the sample compared with the carburized sample.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.10a
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• pp.216-216
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• 1998

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.11a
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• pp.13-13
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• 1996

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.05a
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• pp.97-97
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• 1996