• Corrosion Science and Technology
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• v.2 no.5
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• pp.219-224
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• 2003

Crevice corrosion of stainless steels in natural seawater was investigated for several post weld treatments; as-annealed, as-welded, pickled, and ground. The results confirmed the effect of the biofilm on the cathodic reaction leading to an ennoblement of the rest potential. The degree of ennoblement of corrosion potential depends on the surface finish. As-annealed and pickled samples show stable corrosion potential approaching to 200 ~ 300 mV (SCE) while as-welded and ground samples show the fluctuating corrosion potential. This points to a situation where there are conflicting effects determining the trend in free corrosion potential. Crevice corrosion initiation will tend to pull the free corrosion potential in the active direction, whereas the presence of biofilm will tend to ennoble corrosion potential. There was no visible attack on UNS S31803, S32550, and 2205W. Therefore, those stainless steel grades appeared to be resistant to crevice corrosion in natural seawater on condition of weld metal.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.152-157
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• 2001

This paper was studied on the characteristics of crevice corrosion prevention of SS 400 in marine environment. In NaCl solution, polarization behavior under the crevice corrosion was investigated. And Weight loss rate of SS 400 applied cathodic protection and non cathodic protection was measured according to the NaCl concentration. The main results obtained are as follows : The weight loss rate of Al-alloy galvanic anode was increased as the concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, that of Al-alloy galvanic anode become decreased. The protective potential of SS 400 used Al-alloy galvanic anode becomes more cathodic polarization with increasing concentration of NaCl solution. Effects of oxygen on the weight loss rate of Al-alloy sacrificial anode for cathodic protection as the concentration of 3.5% NaCl solution become sensitive than that of 0% NaCl solution.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.3
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• pp.199-209
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• 2014

Crevice corrosion tests were conducted to examine the corrosion properties of HYBRID (HYdrazine Base Reductive metal Ion Decontamination) which was developed to decontaminate the PWR primary coolant system. To compare the corrosion properties of HYBRID with commonly existing decontamination agents, oxalic acid (OA) and citric oxalic acid (CITROX) were also examined. Type 304 Stainless Steel (304 SS) and Alloy 600 which are major components of the primary coolant system in Pressurized Water Reactor (PWR) were evaluated. Crevice corrosion tests were conducted under very aggressive conditions to confirm quickly the corrosion properties of primary coolant system structure components which have high corrosion resistance. Pitting and IGA were occurred in crevice surface under OA and CITROX conditions. But localized corrosion was not observed under HYBRID condition. Very low corrosion rate of less than $1.3{\times}10^{-3}{\mu}m/h$ was observed under HYBRID condition for both materials. On the other hand, under OA condition, Alloy 600 indicated comparatively uniform corrosion rate of $4.0{\times}10^{-2}{\mu}m/h$ but 304 SS indicated rapid accelerated corrosion in lower case than pH 2.0. In case of HYBRID condition, general corrosion and crevice corrosion were scarcely occurred. Therefore, material integrity of HYBRID in decontamination of primary coolant system in pressurized water reactor (PWR) reactor was conformed.

• Corrosion Science and Technology
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• v.10 no.5
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• pp.180-188
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• 2011

In the present study, denting corrosion experiments were performed as a function of crevice gap size (50, 100 and 200 ${\mu}m$) in a solution containing 3,500 ppm NaCl + 0.2 M $CuCl_2$ (pH = 3 adjusted by HCl). The effects of chloride ion concentrations (3, 3,500 and 35,000 ppm as NaCl) were also outlined with two different crevice gap sizes (100, 200 ${\mu}m$). In addition, the effect of NiB on the denting corrosion was also investigated in a solution of 35,000 ppm NaCl + 0.2 M $CuCl_2$ (pH = 3 adjusted by HCl). The results showed that denting rate increased with the increasing crevice gap size at an initial stage and became nearly constant afterwards. As the concentration of chloride ion increased, the denting rate also increased. However, the addition of a NiB powder of 4 g/L in to the acid-chloride solution was observed to suppress the denting rate significantly.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.131-137
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• 2003

Backfire occurrence must be controlled for the practical use of hydrogen fueled engine. It was found from preceeding studies that crevice volume around piston rings could effect a backfire occurrence. In this study, a possible countermeasure to backfire occurrence was evaluated by using multi point ignition method around piston ring. The results showed that backfire limited equivalence ratio was increased by a little due to a enhancing effect of mixture combustion around piston crevice volume.

• Corrosion Science and Technology
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• v.2 no.6
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• pp.272-276
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• 2003

High nitrogen-bearing stainless steel (HNS) containing more than Imass% N was successfully created by means of pressurized electro-slag remelting (P-ESR) without the addition of manganese. Excellent localized corrosion resistant properties of the HNS were confirmed in terms of pitting and crevice corrosion in artificial seawater. The repassivation kinetics proved higher repassivation rate for HNS.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.487-492
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• 2010

For developing a two-stroke free-piston hydrogen engine with high efficiency and low emission, determination of the scavenging type is one of the most important factor. In this research, backfire characteristics for loop scavenging were analyzed with the number of piston crevice volume and piston expansion speed. Rapid Compression Expansion Machine, RCEM was used for combustion research of the free piston $H_2$ engine in the experiment. As the results, it was shown that although backfire occurring in a loop scavenging type can be partially controled by a complete exhaust of burned gas, possibility of backfire basically exist due to the structure which piston crevice volumes contact with fresh mixture in a scavenging port. However, a loop scavenging may be considered as combustion chamber of a free piston $H_2$ engine from the point of view that backfire does not occur nearby lean equivalence ratio obtained high thermal efficiency. It was also analyzed that an advances of backfire occurrence timing with increase of the fuel-air equivalence ratio were due to promotion of flame propagation into piston crevice volumes by decrease of the quenching distance.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.5
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• pp.672-686
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• 1999

The purpose of this study was to compare the casting problem and corrosion behavior in two types of HL Hexed abutments of the Steri-Oss system ; gold/plastic coping and gold coping. The anodic Polarization behavior, the galvanic corrosion between abutments and Type III gold alloys, before and after casting were analyzed, and the crevice corrosion of casting samples was analyzed with the CPPT test and the SEM. The results are as follows : 1. Anodic polarization behavior of samples ; Before casting, gold/plastic coping and gold coping was shown to have a similar corrosion pat-terns. Type III casting gold alloy was shown to have a lower corrosion potential and passivation film. Corrosion potential of the case of gold/plastic coping after casting was higher than that of gold coping, but the region of passivation film for gold/plastic coping was smaller than that of gold coping. 2. Galvanic corrosion behavior of samples ; Contact current density between casting gold alloys and gold/plastic before casting was higher than that between gold coping and casting gold alloy Galvanic corrosion of samples after casting was shown to have similar contact current density 3. Crevice corrosion behavior of samples ; Crevice corrosion resistance of casting sample using gold coping was lower than that of cast-ing sample using gold/plastic coping, and a severe corrosion pattern was observed at the abutment-casting gold alloy interface by the SEM.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.1
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• pp.66-72
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• 2000

In these days, with development of industry, the use of machines and structures like ships, airplanes, bridges, power plants, and structure for construction has increased and these machines and structures are used in various corrosive environment. Especially, in case of STS 304, which is material for every kind of machine and chemical plant, it makes many problems related with corrosion and as a result of this, there are happening tremendous economic loss. Therefor, in this study, the test for polarization characteristics was carried out to study characteristics of crevice corrosion of STS 304 which is austenitic stainless steel, in NaCl environment.The main results obtained are as follows :1) Part of crevice is corroded, neighboring outside surface of crevice is passivation. 2) In polarization behavior, corrosion potential of STS 304 become more noble as the concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5% that of STS 3.4 become less noble. 3) The current density under corrosion potential was high drained as concentration of NaCl solution increased by 3.5% but the concentration increased over 3.5%, the current density was low drained.