DOI： 10.2355/isijinternational.ISIJINT-2020-018

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DOI： 10.2355/isijinternational.ISIJINT-2020-502

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DOI： 10.2355/isijinternational.ISIJINT-2020-426

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DOI： 10.2355/isijinternational.61.1055

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DOI： 10.2320/matertrans.MT-M2020298

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DOI： 10.1051/matecconf/202032106002

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DOI： 10.2472/jsms.69.810

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掲載種別：研究論文（学術雑誌）  

Stress corrosion cracking (SCC) behavior of SUS316L stainless steel in the chloride solution containing thiosulfate has been investigated by using a slow strain rate technique (SSRT). The susceptibility of SCC was found to depend on the strain rate, the concentration of thiosulfate and chloride, and pH. The highest susceptibility was obtained at the condition of 20 mass % NaCl containing 10-2 kmol·m-3 Na2S2O3 at pH 5.3 and 2.2 × 10-7 s-1. Observations of fractured specimens showed that cracks perpendicular to the tensile axis generated at the pits. The initial fracture mode of the crack was intergranular, followed by transgranular and dimple with propagation of the crack. Intergranular fracture initiated from intergranular corrosion on the bottom of the pit, in which pH decreased less than 2. Immediately after immersion, pits generated easily because the dissolved oxygen with thiosulfate rapidly raise free corrosion potential upto pitting potential in cooperation with the action of thiosulfate to lower the pitting potential. Decrease in pH caused lowering of pitting potential and increase of the number of cracks, while the highest SCC susceptibility was obtained at pH 5.3. At conditions showing the high SCC susceptibility, corrosion potential was always in the range between -400 and -370 mV (Ag/AgCl). Therefore, the SCC behavior in this system is strongly controlled by the electrochemical factors.

DOI： 10.2355/tetsutohagane1955.77.9_1511

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DOI： 10.34562/jic.59.1_156

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DOI： 10.34562/jic.59.1_161

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DOI： 10.3323/jcorr.69.73

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J-GLOBAL

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DOI： 10.2320/jinstmet.J2018034

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DOI： 10.3323/jcorr.67.375

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2320/matertrans.M2017196

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DOI： 10.4139/sfj.68.201

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

Thin water film is formed on metal surfaces that are exposed to the atmosphere. The conditions of this film change according to environmental factors, such as temperature, wind, and rainfall. Hence, it is difficult to investigate atmospheric corrosion on metal surfaces.
This paper aimed to develop a measurement system for the pH distribution on a metal surface in simulated atmospheric environment. The surface pH distribution was measured with agar film including pH indicators and MgCl2. The pH indicators used were a universal indicator and an MR-BTB indicator. Agar film of 0.5 mm thickness was placed on an iron specimen. The specimen was set in a chamber with a relative humidity of 100% to prevent the agar film from drying out. The surface pH distribution was determined from the color of the agar film with an RGB color model. The surface pH distribution on the iron showed that anodic reactions produced acidic regions and cathodic reactions produced basic regions. The observed phenomena were the same as that found under a water droplet which contained the pH indicator and MgCl2. Therefore, we conclude that the agar film could simulate thin water film in an atmospheric environment and allow measurement of the surface pH distribution on iron under atmospheric corrosion.

DOI： 10.2320/jinstmet.JAW201704

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掲載種別：研究論文（国際会議プロシーディングス）  

© 2017 ICF 2017 - 14th International Conference on Fracture. All rights reserved. The research have tried to reveal the effect of annealing temperature on susceptibility to hydrogen embrittlement (HE) of the interstitial-free steel with ultra-fine grain (UFG) structure produced by an accumulative roll-bonding (ARB) method. The as-ARBed specimen exhibited the UFG structure with a large tensile strength. As hydrogen was introduced to the specimen, a fracture strain decreased remarkably. As the annealing temperature rose to 673 K, the tensile strength was slightly diminished. The fracture strain of the annealed specimen with hydrogen increased drastically with a rise in the annealing temperature. As the temperature further rose above 773 K, almost no change in the strain was obtained between the specimens with and without hydrogen, and the strength decreased remarkably.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Trans Tech Publications Ltd  

The behavior of environment-assisted cracking (EAC) for super-elastic TiNi alloy was investigated as functions of solution pH and electrochemical potential. The specimen was immersed in sulfate solutions at various pHs, and subjected to a potentiostatic slow strain rate tensile test. As a result, the EAC map for the TiNi alloy as functions of the solution pH and the applied potential was successfully produced, and it was revealed that larger EAC susceptibility was obtained in the region of lower potential and lower pH. The tendency was quite typical for hydrogen embrittlement, but not similar to that of TiAl. The EAC susceptibility was classified by cathodic charge density, irrespective to pH nor potential: The charge density larger than 0.025 MC.m-2 induced a maximum EAC susceptibility.

DOI： 10.4028/www.scientific.net/MSF.879.709

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

This paper aimed to investigate conditions for pit initiation on type 304 stainless steel under MgCl2 solution layer in atmospheric environment using a CCD camera system and a surface potential measurement equipment. A droplet of dilute MgCl2 solution was put on the specimen. The specimen was set in the chamber with a relative humidity of 33% in order to make the droplet dry into the layer. The CCD camera system was employed to observe the change in the shape of the droplet and in the specimen surface during the drying process. In addition, the surface potential measurement equipment was applied for monitoring the surface potential of the specimen with the layer. When the droplet of dilute solution became thin and saturated, pitting corrosion occurred and the surface potential rapidly lowered. By contrast, thick and saturated layer did not induce pitting corrosion and the surface potential indicated the relatively low and steady. Therefore, it was revealed that the atmospheric corrosion occurred on the steel under saturated MgCl2 solution layer whose thickness less than 0.2 mm.

DOI： 10.2320/jinstmet.JAW201607

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3323/jcorr.65.264

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

Effect of hardness of steels on hydrogen absorption behavior has been investigated by means of conventional electrochemical hydrogen permeation test. Empirical transient curves of hydrogen permeation current density were agreed with the theoretical one on the basis of Fick's second law with a fixed hydrogen concentration at the hydrogen absorption surface, C-0, at any time. The fact suggests quasi-equilibrium condition to the absorption-desorption reaction of hydrogen at the surface, and that correlation between C-0 and hydrogen absorption rate. As an analytical result of the transient, a diffusion coefficient of hydrogen, D, decreased with an increase in a hardness of the steel. On the other hand, the value of C-0 increased with an increase in the hardness. There was a good positive correlation between C-0 and an inverse of D in spite of difference in the hardness and the additional element. The fact may suggest that the microstructural defects attract hydrogen both in the bulk and on the surface of the steel, and the effect promotes hydrogen ad-atom absorbing into the iron specimen.

DOI： 10.2355/isijinternational.ISIJINT-2015-283

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記述言語：日本語   出版者・発行元：公益社団法人 腐食防食学会  

DOI： 10.3323/jcorr.65.43

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

Effects of additional elements of Cr and Ni in iron on hydrogen absorption behavior have been investigated by means of conventional electrochemical hydrogen permeation test. Empirical transient curve of hydrogen permeation current density was agreed with theoretical one on the basis of Fick's second law with a fixed hydrogen concentration at the hydrogen absorption surface, C-0, at any time. The fact suggests quasi-equilibrium condition to the absorption-desorption reaction of hydrogen at the surface, and that correlation between C-0 and hydrogen absorption rate. As an analytical result of the transient, a diffusion coefficient decreased with an increase in a content of additional elements, and the decrement was enhanced much more by Cr than by Ni. C-0 was almost proportional to a square root of the cathodic current density at the hydrogen absorption surface for any specimens. The slope increased with an increase in a content of the additional elements, and the increment was enhanced much more by Cr than by Ni. There was a correlation between the slope and the diffusion coefficient, and the correlation suggested that the additional elements of Cr and Ni attract hydrogen. In addition, the attraction effect of Cr was much more than that of Ni. Under anodic potential region, the effect of additional element on C-0 was not clearly obtained in the solution of pH 2, but it is found that C-0 of the Cr-added steel was larger and that of the Ni-added steel was smaller than that of Fe in the solution of pH 6.

DOI： 10.2355/isijinternational.ISIJINT-2015-223

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

The susceptibility to environment-assisted cracking (EAC) of super-elastic TiNi alloy was investigated as a function of the electrochemical potential and solution pH. The investigation was conducted using a slow-strain-rate tensile test apparatus with a potentiostat. The test solutions were sulfate solutions with various pH values adjusted by H2SO4 or NaOH. The alloy deforming under cathodic reaction fractured under the relatively small strain where the alloy was in the stress-induced martensitic phase. A larger EAC susceptibility was obtained at lower potential and lower pH, which indicates that this is a general feature of hydrogen embrittlement. The severe EAC region of TiNi alloy was different from that of TiAl alloy. The EAC susceptibility was strongly correlated with the cathodic charge density, irrespective of the pH or potential: a charge density below 0.025 MC m(-2) yielded almost no EAC; however, above 0.025 MC m(-2) EAC was induced, and the EAC susceptibility was independent of the charge density. Hydrogen in solid-solution state was detected in the alloy at a charge density below 0.025 MC m(-2), and hydride started to form at a density above 0.025 MC m(-2).

DOI： 10.2320/matertrans.MI201511

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：TRANS TECH PUBLICATIONS LTD  

Effect of potential on hydrogen evolution during simulated pitting of aluminum has been investigated. Aluminum wire in 1.0 mm diameter was mounted in resin, immersed in 0.6 kmol.m(-3) NaCl solution and anodically dissolved in axial direction by applying a constant potential from -0.6 to -0.1 V-Ag/AgCl for 86.4 ks. In addition, a resistance of the solution in the crevice of the resin where the aluminum wire corroded was simultaneously measured by superimposing high-frequency alternating potential (Ep-p=10 mV) to the main potential. As higher main potential was applied, the corrosion depth increased. Hydrogen evolved at the corroded site although the anodic potentials were applied. The amount of hydrogen evolution increased as higher main potential was applied to the wire. An interfacial potential (E-int) at just the wire surface was calculated from applied main potential (E-app), solution resistance (R-sol) and current(I) as E-int = E-app - I.R-sol. The interfacial potential was about -0.7 to -1.0 V-Ag/AgCl, and became lower as the higher main potential was applied. The lower interfacial potential may cause hydrogen evolution in this case.

DOI： 10.4028/www.scientific.net/MSF.794-796.107

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記述言語：日本語   出版者・発行元：Japan Society of Corrosion Engineering  

チタンは機械的性質，生体適合性，鋳造技術の発展，塩化物水溶液に対する耐食性の観点から歯科医療部材用材料として使用されている．一方，フッ素は脱灰の抑制や再石灰化の促進，歯膜や歯垢の抑制，微生物増殖の抑制などを示すう蝕抑制剤として広く使用されている．しかし，Tiにはフッ化物水溶液中で溶解する性質があり，Ti製歯科用器具に対する腐食問題が報告されている．この問題への対策の一つに，フッ化物水溶液に耐食性を示す新しいTi合金の開発が挙げられる．本報では，フッ化物水溶液中におけるTiの腐食特性を概説した後に，最近行われているフッ化物水溶液に耐食性を示す新しいTi合金の開発への取り組みを紹介する．

DOI： 10.3323/jcorr.63.309

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

We have developed Ti-Mg alloy for dental material corrosion-resistant to aqueous fluoride solutions. Ti plates and granular Mg was put in a sealed vessel and heated at 950 degrees C, so Ti plates were exposed in the liquid and the vapor Mg phases. The conditions made Mg diffuse into the Ti plates to produce Ti-Mg alloy. The Ti-Mg alloy produced in the vapor Mg phase for 430 h achieved homogeneous distribution in Mg concentration of 0.2 at%. A Vickers micro hardness increased almost linearly with an increase in the Mg concentration, and the hardness of the homogeneous Ti-0.2at%Mg was about 1.2 times larger than that of Ti before alloying. It was confirmed that corrosion resistance of Ti in the fluoride solution was improved by alloying with Mg. The method using the vapor Mg phase contributed much more effective improvement of corrosion resistance than that using the liquid phase. The homogeneous Ti-0.2 at% Mg demonstrated a maximum corrosion resistance of all the specimens, by about 80 times to Ti.

DOI： 10.2320/matertrans.MC201210

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

We have developed Ti-Mg alloy for dental material corrosion. resistant to aqueous fluoride solutions. Ti plates and granular Mg was put in a sealed vessel and heated at 950 degrees C, so Ti plates were exposed in the liquid and the vapor Mg phases. The conditions made Mg diffuse into the Ti plates to produce Ti. Mg alloy. The Ti. Mg alloy produced in the vapor Mg phase for 430 h achieved homogeneous distribution in Mg concentration of 0.2 at%. A Vickers micro hardness increased almost linearly with an increase in the Mg concentration, and the hardness of the homogeneous Ti-0.2 at%. Mg was about 1.2 times larger than that of Ti before alloying. It was confirmed that corrosion resistance of Ti in the fluoride solution was improved by alloying with Mg. The method using the vapor Mg phase contributed much more effective improvement of corrosion resistance than that using the liquid phase. The homogeneous Ti-0.2 at%. Mg demonstrated a maximum corrosion resistance of all the specimens, by about 80 times to Ti.

DOI： 10.2320/jinstmet.J2013026

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DOI： 10.2320/jinstmet.76.314

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

We have investigated correlation between grain boundary character and susceptibility to sensitization using SUS304 stainless steel foil with coarse grained structure. The steel foil of 100 mu m thickness was heated at 1473 K for several periods, and a heating time of 604.8 ks was selected to prepare the specimen with coarse grained structure, in which a median of grain size was 229 mu m. In the specimen, most of grain boundary planes were parallel to the thickness direction. The specimen was sensitized and subjected to the grain boundary corrosion test in oxalic acid solution. Thereafter, the orientation of each grain and the Sigma value of each grain boundary were determined by the electron backscattering diffraction (EBSD) method. The corrosion width at the grain boundary positively corresponding to a degree of sensitization increased with an increase in Sigma value, and became stable as the value was more than 19. In addition, the corrosion width at Sigma 3 grain boundary was scattered. Since most of the grain boundary planes were parallel to the thickness direction of the specimen, orientation to each plane of Sigma 3 grain boundary was determined from the EBSD results, and the degree of coincidence for atom sites on the Sigma 3 plane was analyzed. As a result, orientations of the observed Sigma 3 planes were parallel to the common rotation axes characterizing Sigma 3 coincidence site lattice (CSL) in space, and the Sigma 3 grain boundary had three types of planes with different CSL. An area of the unit cell for CSL of the grain boundary plane identified as Sigma 3 was selected as an index of grain boundary character, and an increase in the area correlated to an increase in the corrosion width.

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記述言語：日本語   出版者・発行元：Japan Society of Corrosion Engineering  

湿潤・乾燥環境中におけるさび付き炭素鋼の吸湿・放湿挙動を定量的に測定することができる装置を開発した．さび付き炭素鋼を試料にして湿度を制御した空気を導入した容器内に設置し，吸湿・放湿に伴う試料の質量変化を精密電子天秤で連続的に測定した．それと同時に容器内の湿度をデジタル湿度計で測定した．湿度が90％以上の空気中では，試料の質量はさびの吸湿によって急激に放物線的に増加し，やがて試料表面への水分の付着によって徐々に直線的に増加した．試験を続けると質量の振動が認められた．突然の質量減少は一部のさび片を含んだ水滴の落下に対応し，その後の直線的な質量の増加は水分の再付着に対応した．90％以下の湿度における質量変化は90％以上の湿度のときと同様であったが，試料からの水滴の落下は認められなかった．湿度88％の空気中で長時間試験を行うと，試料に吸収・付着した水分の質量は試験時間に依存せず，新しく生成したさびの質量は時間の経過とともに直線的に増加することがわかった．また，さびの質量増加速度すなわち腐食速度は厚い水膜中に存在する溶存酸素の拡散が律速したカソード反応速度に対応することが示唆された．

DOI： 10.3323/jcorr.61.113

CiNii Books

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その他リンク： https://jlc.jst.go.jp/DN/JALC/10003305774?from=CiNii

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：TRANS TECH PUBLICATIONS LTD  

It has been tried to develop Ti-Ca alloys which demonstrates corrosion resistance in an aqueous fluoride solutions. The Ti-Ca alloys were produced by diffusion-metallizing method A Ti plate and Ca grains were put in a sealed container of stainless steel As the container was heated at 1000 degrees C, Ca was melted and partially vaporized in the inner space Ca then contacts and permeats into the Ti plate to metallize In a holding time of 450 h, the alloy surface consisted of two layers, the first was oxide layer and the second was metal layer of about 200 pm thick. A Vickers micro hardness of the second layer was quite large, upto about 600 Hv. Evaluation of corrosion resistance for the second layer and the inner part was carried out by electrochemical potentiokinetic method. Test solutions were aqueous fluoride solutions produced with HF and NaF. A concentration of fluoride ion was fixed to 0.024 kmol m(-3), and pH of the solution was varied from 3 4 to 4 7. As a result, both Ti and Ti-Ca alloy were passivated under natural immersion condition in the solution of pH 4.7. At pH 3 4, on the other hand, Ti was actively dissolved, but Ti-Ca alloy was still passivated, that means Ti-Ca alloy performs much better corrosion resistance than Ti.

DOI： 10.4028/www.scientific.net/MSF.638-642.564

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：TRANS TECH PUBLICATIONS LTD  

We have investigated the susceptibility to hydrogen embrittlement of interstitial-free (IF) steel with ultrafine-grained microstructure produced by accumulative roll-bonding (ARB) process. The ARB process was conducted to as-received IF steel at 773 K, and repeated to five cycles. The as-received and the ARBed IF steels were cut into tensile specimens, and then hydrogen was electrochemically charged to the specimens in a sulfuric acid solution of pH 2.5 at a cathodic current density of 50 A m(-2) for several charging times. Immediately after the hydrogen-charging process, tensile test was conducted at ambient temperature and an initial strain rate of 3.3 x 10(-4) s(-1). Besides, state and amount of hydrogen absorbed in the specimen were determined with a thermal desorption gas spectroscopy (TDS) at a heating rate of 5.6 x 10(-2) K s(-1). As a result, almost no hydrogen was absorbed in the as-received IF steel charged for a long time of ca. 300 ks, and a fracture strain of the steel was independent of the charging time. On the other hand, amount of hydrogen in the 5-cycle ARBed steel increased with an increase in the charging time, and the fracture strain decreased with an increase in the charging time, indicating that the ARBed steel exhibited susceptibility to hydrogen embrittlement.

DOI： 10.4028/www.scientific.net/MSF.654-656.1235

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記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Elsevier Ltd  

This chapter investigates the influences of potential and pH on environment-assisted cracking behavior (EAC) in order to identify the effects of environmental factors on EAC. EAC tests are conducted with the slow strain rate technique. The material chosen is Ti-6AI-4V. An aqueous solution of Na2SO4 is used for EAC tests. The solution is prepared with distilled water and reagent-grade chemicals. The slow strain rate tensile (SSRT) test equipment SSRT-MINI1000T with a glass cell is employed for the tests. The side and fracture surfaces of specimens are analyzed with a scanning electron microscope. The density of the cathodic current is observed during the EAC test at all potentials except +200 mV, at which the density of anodic current is observed. The current densities are virtually constant throughout the test period, and the density of cathodic current increases with the decrease in potential. Identical trends are observed at pH 3 and 7. At pH 3, the density of the cathodic current increases with decreasing potential. The maximum stress is almost identical to that in air, although it appears to decrease slightly at -300 mV. Therefore, almost no EAC susceptibility is observed at pH 3. Similar trends are observed at pH 7. At pH 1, a unique behavior in maximum stress against potential is observed. © 2008 Elsevier Ltd All rights reserved.

DOI： 10.1016/B978-008044635-6.50034-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

To investigate the influence of local stress on initiation behavior of stress corrosion cracking (SCC) for sensitized Type 304 stainless steel, cracking process during constant load SCC test was monitored and recorded with an in situ crack observation system. The changes in number of cracks, sum of crack length and cracked area on the specimen surface with test time were identified from the cracking images analyzed by image processing. In the SCC tests, many cracks were initiated and coalesced on the surface, and the coalescence of cracks played an important role to primary crack growth. The influence of applied stress on crack initiation was different from that on crack growth. In addition, there was a difference between influences of stress on incubation period to crack initiation and crack initiation rate. Due to these differences, a stress of 0.8S(y) was thought to cause relatively many cracks compared with 0.5S(y) and 1.3S(y), (S-y = 200 MPa). Through quantitative estimation of distribution in local stress around a crack by finite element analysis method, it was deduced that the crack initiation is influenced not only by bulk stress applied at the end of the body, but also by local stress formed around pre-existing cracks. According to pre-existing cracks, stress enhancement accelerates the crack growth, while the stress relaxation causes the suppression of new crack initiation. Based on the experiment and analysis results, three types of growth process were suggested, which are caused by propagation itself, by new crack initiation at vicinity of the crack tip, and by coalescence of approaching cracks. Then, it was concluded that, in order to predict/simulate the cracking behavior of this SCC system, the influence of local stress on the crack initiation should be taken into account. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.corsci.2007.01.011

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

The high strength Al alloys, 7N01, 6061 and 5083, were examined using slow strain rate testing in chloride-containing acid to neutral solutions under potentiostatic control. Large amounts of hydrogen absorption occurred at potentials above the breakdown potential. In this potential range, the mechanical strength of the alloys is degraded manly by severe general corrosion but hydrogen embrittlement may also occur. On the other hand, polarisation at more negative potentials where there is intense hydrogen evolution does not necessarily lead to a large amount of hydrogen entry except for the case of the alloy 5083, which suffered from hydrogen embrittlement induced by hydride formation around precipitates. copyright The Electrochemical Society.

DOI： 10.1149/1.2789226

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

To investigate the initiation behavior of stress corrosion cracking (SCC) for sensitized Type 304 stainless steel in high temperature water, a constant load SCC test method combined with in situ crack observation technique was employed. The in situ crack observation system allowed us to detect small cracks of at least 100 mu m. As a result, a fracture time decreased with an increase in an applied stress. The first cracks were observed at most 3 h before the specimen was fractured under all the stress conditions. After that, many cracks were initiated in a short time to fracture. The fracture was caused by coalescence of multiple cracks rather than by growth of some primary cracks. The simulation model for surface crack initiation was newly developed using a Monte Carlo method, which was based on damage mechanics and stress analysis around the existing cracks. The simulation could represent the empirical results of changes in the crack distribution and the cumulative number of cracks during the SCC tests. It was concluded, therefore, that the crack initiation process should be considered in simulating the life prediction of the material in this SCC system. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.corsci.2005.09.015

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DOI： 10.1016/j.corsci.2004.10.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

We have investigated the influences of potential and pH on environment-assisted cracking (EAC) of Ti-6Al-4V in aqueous solutions. The EAC test was conducted by slow strain rate technique. Solution pH was controlled from I to 7, and applied potential was fixed between -1.8 and +0.2 V-SHE. In the solutions of pHs 3 and 7. mechanical properties of the material was almost independent of applied potential. This means that the material shows almost no EAC susceptibility in the potential-pH region for the EAC test period. At pH 1, however, both maximum stress and fracture strain changed with applied potential, and showed minimum values at an applied potential of about -1.0 V-SHE. According to surface analyses by scanning electron microscopy and X-ray diffraction technique, some cracks and Ti hydride were detected from only the specimens fractured at about -1.0 V-SHE in the solution of pH 1. Therefore, it can be concluded that Ti-6Al-4V is most susceptible to the EAC at about -1.0 V-SHE and a pH less than 1. The EAC region was in good agreement with Ti ion stable region in a potential-pH diagram of Ti/water system, and was quite similar to that on the EAC of TiAl.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Inhibition effect of metal cation to intergranular stress corrosion cracking (TGSCC) of sensitized Type 304 stainless steel has been investigated by slow strain rate technique (SSRT) with a dynamic crack observation system. The SCC tests were conducted in fully-deaerated aqueous solutions containing various metal sulfates of 10(-5) kmol/m(3) at 95 degrees C. Metal cations of Na+, Ca2+ Mn2+ and Zn2+ were selected in this study, and were characterized by a hardness based on the hard and soft acids and bases (HSAB) concept. As a result, it was found that a hard metal cation in the test solution increased crack initiation time and decreased mean crack initiation frequency. In other words, metal cations with larger hardness have an ability of suppressing initiation process of the IGSCC. On the other hand, apparent mean crack velocity was independent of the hardness of metal cation. The finding that the metal cations with large hardness inhibit initiation of the IGSCC was able to be rationally explained on the basis of the passive film model combined with the HSAB concept. (c) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.corsci.2004.06.014

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ASSOC CORROSION ENG  

A slow strain rate testing apparatus equipped with an autoclave as well as with an in-situ crack observation system has been newly developed. Using this system, the growth behavior of multiple cracks in high-temperature water up to about 300 degreesC could be observed in-situ. In this study, the initiation and propagation of stress corrosion cracks in sensitized Type 304 (UNS S30400) stainless steel immersed in 10(-4) kmol/ m(3) sodium sulfate (Na2SO4) solution from 100 degreesC to 250 degreesC were investigated. It was found that stress corrosion cracking (SCC) susceptibility evaluated from the time to fracture increased with an increase in temperature. The in-situ observations of the cracks revealed the following:
-The time to initiate the first crack decreased with art increase in temperature.
-The cumulative number of cracks increased almost linearly with deformation time at any temperature.
-Both the final number of cracks and the crack initiation frequency exhibited a maximum at 150 degreesC.
-The distribution in the crack propagation rates was found to fit the Weibull probability distribution. The mean crack propagation rate increased with an increase in temperature according to the Arrhenius relation with an estimated activation energy of about 2.1 kcal/mol.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

A Scanning Laser-Enhanced Electrochemical Microscope for Hydrogen detection (H-SLEEM) has been developed in order to in-situ visualize the distribution of hydrogen localized on a steel surface. Introduction and detection of hydrogen for the steel sheet was conducted by hydrogen permeation technique with a pair of electrochemical cells. When the hydrogen detection side under hydrogen permeation is irradiated with focused Ar laser, anodic current relating to hydrogen oxidation reaction is thermally enhanced at the irradiation spot and then anodic current Increment corresponding to the hydrogen permeation rate at the spot is expected to be determined. In the case that whole the hydrogen detection side was irradiated with diffused laser, the anodic current increased and the current increment increased with an increase in the hydrogen permeation current. The use of focused laser also permitted the measurement of the anodic current increment depending on the hydrogen permeation current. The modulated laser provided more stable and reproducible current increment. When the specimen whose hydrogen entry side was masked except for a small exposed area in center was employed and the modulated laser was raster-scanned under hydrogen permeation, a very clear image of the two-dimensional distribution in the current increment corresponding to local hydrogen permeation rate on the detection side was obtained. It is concluded that the H-SLEEM can successfully visualize the localized hydrogen distribution on the steel surface.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：MINERALS, METALS & MATERIALS SOC  

In previous work, we had investigated environment-assisted cracking (EAC) behavior of gamma-TiAl in 0.05 M sulfate solutions as functions of pH and potential by using slow strain rate tensile test, and plotted the EAC susceptibility in the potential-pH diagram of Ti-H2O and Al-H2O Systems. From the results, we had revealed that the EAC susceptibility was in distinct agreement with the diagram of Ti-H2O system, and especially severe EAC susceptibility located in Ti ion (i.e., Ti2+, Ti3+) stable region. In this work, we have extensively investigated the effect of strain rate in the range from 10(-3) to 10(-7) s(-1) on the EAC susceptibility of the material in the same solution of pH 3. At Ti oxide stable potential of +200 mV, the EAC susceptibility was almost independent of the strain rate, similar to that under vacuum condition. While, the susceptibility was found to increase with lowering the strain rate at Ti hydride stable potential of -2000 mV. At Ti ion stable potential of -1250 mV, tendency of EAC susceptibility with strain rate was similar to that at -2000 mV. However, a decrease in the susceptibility was found at the slowest strain rate. Xray diffraction method indicated that the additional peak relating to hydride presence at -1250 mV, although only a substrate TiAl peak was found at -200 mV. At -2000 mV, no hydride peak over the strain rate range was evident except for the slowest strain rate. The intensity of the hydride peak increased with lowering the strain rate except for the lowest strain rate where the intensity goes down at -1250 mV. At -2000 mV, on the other band, the susceptibility decreased with a decrease in the strain rate, even where no hydride detected by a conventional system. It is concluded that the very thin hydride may induce the EAC of the material, and the susceptibility increases with the increase in the amount of hydride.

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DOI： 10.1016/S0010-938X(03)00031-3

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(Dec. 15, 2001)

DOI： 10.3323/jcorr1991.51.350

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Environment-assisted cracking (EAC) of γ-TiAl has been investigated from electrochemical viewpoint. The TiAl was forged at 1373 K and annealed at 1073 K for 7.2 ks. The specimen whose potential was controlled was tested in aqueous sulfate solutions of various pHs at room temperature by using a slow strain rate tensile testing apparatus. The experimental EAC results evaluated by the maximum stress was discussed on the basis of the potential-pH diagram of Al and Ti/water system. It was revealed that the diagram of Ti/water system can predict the EAC susceptibility of TiAl, although the diagram of Al/water system shows almost no relation to the susceptibility. The results suggest that the EAC of TiAl is controlled by the stability of Ti oxide, hydride, and ion on the solution/substrate interface, which affect the entry of hydrogen into the material. © 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-5093(01)01654-9

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(2000.10.12)

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

【工学部論文データから移行】

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

Environment-assisted cracking (EAC) of gamma-TiAl has been investigated from electrochemical viewpoint. The material whose potential was controlled was tested in aqueous sulfate solutions of various pHs at room temperature by using a slow strain rate tensile testing apparatus. The TiAl forged at 1373 K and annealed at 1073 K for 7.2 ks was used in the EAC test. It was found in the alkaline and the natural solution that maximum stress was independent of the potential in higher potential region, and decreased with decrease in the potential in the lower potential region. In acidic solution, the maximum stress changed with the potential as follows; the maximum stress was independent of the potential above -200 mV(SHE), decreased with decrease in the potential between -200 and -1000 mV(SHE), and increased with decrease in the potential below -1000 mV(SHE). The experimental EAC results was discussed on the basis of the potential-pH diagram of Al and Ti/water system. It was revealed that the diagram of Ti/water system can predict the EAC susceptibility of TiAl, although the diagram of Al/water system shows almost no relation to the susceptibility. Therefore, the EAC of TiAl is controlled by the stability of Ti oxide, hydride, and ion on the solution/base material interface, which affect the entry of hydrogen into the material. (C) 2000 Elsevier Science Ltd. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The effect of concentration and type of anions on stress corrosion cracking of sensitized type 304 stainless steel was investigated by slow strain rate test (SSRT) with a dynamic cracking observation system. It was found that difference of anion type added into pure water exerted a significant effect on crack initiation time and mean crack initiation frequency. Some anions, such as OH- and B4O72-, can suppress, while others, such as S2O32- and SO42-, accelerate crack initiation. The effect of anion type on the crack initiation behavior was explained on the basis of the passive film model proposed by Okamoto and Shibata and a HSAB (hard and soft acids and bases) concept. The anion having a larger hardness value was found to show a longer crack initiation time or to delay the crack initiation. The anion with a larger hardness, that is expected to show a stronger affinity to proton, is considered to accelerate deprotonization, and to enhance the repassivation process. Consequently, the harder anion is expected to induce a more perfect passive film more rapidly, and then to retard the crack initiation more effectively. (C) 2000 Elsevier Science Ltd. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：E D P SCIENCES  

The crack initiation and propagation behavior of a sensitized Type 304 stainless steel in distilled water containing small amounts of Na2SO4 or Na2B4O7 impurities was investigated by using slow strain rate technique (SSRT) with an insitu cracking observation system, and analyzed with a statistical approach. It was found that the crack initiation time for the steel in Na2SO4 or Na2B4O7 solutions obeyed the exponential distribution, while K-ISCC and crack velocity obeyed the Weibull distribution. An increase in Na2B4O7 concentration decreased the SCC susceptibility of the steel by delaying crack initiation time, reducing the crack initiation rate and increasing K-ISCC. In contrast, an increase in Na2SO4 concentration increased SCC susceptibility of the steel by shortening crack initiation time and accelerating crack propagation.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(1999.6.21)

DOI： 10.3323/jcorr1991.49.138

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(1999.7.12)

DOI： 10.3323/jcorr1991.49.144

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記述言語：英語   掲載種別：研究論文（その他学術会議資料等）  

【工学部論文データから移行】

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(1999.5.19)

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(1999.07.22)

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(1999.4.3)

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

The stress corrosion cracking (SCC) of sensitized Type 304 stainless steel has been examined in Na2B4O7 + Na2SO4 solutions with a constant solution conductivity by using the slow strain rate test (SSRT). The cracking behavior was observed in-situ by a dynamic observation system with a charge-coupled device (CCD) camera. It was found that an increase in the k (= [Na2B4O7]/[Na2SO4]) value, or borate concentration, leads to a decrease in the SCC susceptibility by retarding crack initiation, namely, by delaying crack initiation time and reducing crack initiation frequency. By contrast, an increase in sulfate concentration enhances SCC susceptibility by shortening crack initiation time and accelerating crack initiation frequency. The critical sulfate concentration to accelerate crack initiation is 10(-5) kmol/m(3) and, below this concentration, the suppressing effect of borate ions on the SCC works. In addition, it is the solution conductivity, rather than the anion type or their concentrations, which control crack propagation. (C) 1999 Elsevier Science Ltd. All rights reserved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ASSN CORROSION ENG  

The effects of solution pH and buffer capacity on intergranular stress corrosion cracking (IGSCC) of sensitized type 304 stainless steel ([SS] UNS S30400) was examined at 95 degrees C by slow strain rate technique (SSRT) with an in-situ cracking observation system, It was found that an increase in solution pH or buffer capacity increased crack initiation time and decreased mean crack initiation frequency, but exerted almost no effect on crack propagation. This inhibition effect on IGSCC initiation was explained as resulting from a retarding effect of solution pH and buffer capacity on the decrease in pH at crack nuclei caused by the hydrolysis of metal ions dissolved when the passive film was ruptured by strain in SSRT.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ASSN CORROSION ENG  

The intergranular stress corrosion cracking (IGSCC) behavior of sensitized type 304 (UNS S30400) stainless steel (SS) in dilute sodium borate (Na2B4O7) solutions at 95 degrees C was examined by slow strain rate testing (SSRT) using a dynamic observation system. The borate ion (B4O72-) suppressed IGSCC susceptibility of sensitized type 303 SS by delaying the crack initiation time and reducing the crack initiation frequency (CIF). The inhibition effect of the borate ion (B4O72-) on crack initiation may have resulted from its buffer effect on local acidification at crack nuclei and its inhibitive nature in reacting with metal ions to form a protective film. However, B4O72- concentration provided no remarkable inhibition effect on crack velocity (CV), which depended mainly upon solution conductivity, within the scattered values. Hydroxyl ions (OH-) also suppressed initiation of IGSCC, but not as effectively as B4O72-. The crack initiation time obeyed the exponential probability distribution, and the CV obeyed the Weibull probability distribution.

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記述言語：日本語   出版者・発行元：腐食防食協会  

DOI： 10.3323/jcorr1991.47.267

CiNii Books

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3323/jcorr1991.47.771

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：PERGAMON-ELSEVIER SCIENCE LTD  

Initiation and propagation of IGSCC for sensitized Type 304 stainless steel in dilute sulfate solutions have been investigated by the slow strain rate test (SSRT) with a CCD camera system. An increase in concentration of sulfate ion was found to cause decrease in crack initiation strain and fracture strain, resulting in the increase in the IGSCC susceptibility. Statistical analysis made it clear that the increase in concentration of sulfate ion had little effect on crack initiation frequency, and crack initiation time obeyed the exponential probability distribution, but the crack velocity obeyed the Weibull probability distribution. With increase in the concentration of sulfate ion, the crack velocity increased, and the number of cracks decreased. On the contrary, the mean crack velocity decreased and the number of cracks increased with time. The dependence of the crack velocity on the concentration of sulfate ion and the number of active cracks under potentiostatic SSRT conditions was successfully explained by a multiple cracks model combined with the mass transport model. (C) 1997 Elsevier Science Ltd.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELECTROCHEMICAL SOC INC  

The point defect model (PDM) has been used to derive the dependence of the pitting potential on the voltage scan rate. Relationships derived from the PDR? predict that the observed pitting potential is a linear function of the square root of voltage scan rate at low scan rates, which agrees with experimental data reported in the literature. Furthermore, the critical concentration of condensed cation vacancies that give rise to passivity breakdown. as estimated from the sweep rate dependence of the pitting potential, is found to be in good agreement with that estimated from structural considerations. The PDM is also used to predict the probability distribution function in the induction time for pitting (t(ind)), that is, the survival probability, by assuming that the maximum diffusivity of the cation vacancy in a population of specimens is log-normally distributed. This calculated ''external'' distribution in the induction time is found to be in reasonable agreement with experimental induction time data for passivity breakdown on multiple specimens of single cn-stal (100) Ni and polycrystalline nickel buffered chloride solutions.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TRANS TECH PUBLICATIONS LTD  

Although grain boundary sliding (GBS) mainly contributes to superplastic deformation, there are few studies on GBS behavior at each boundary in superplastic materials. It has been investigated the effect of three grain boundary characters of the angle between grain boundary at the specimen surface and the tensile direction, the kind of adjacent grains across a grain boundary, and Sigma value which was calculated from orientations of adjacent grains across a grain boundary on GBS in a superplastic Pb-Sn alloy.
The superplastic behavior is found when GBS takes place at most of grain boundaries. It is considered that GBS is easier at a grain boundary both with the higher angle between grain boundary and tensile direction, and with the same kind of adjacent grains across a grain boundary. GBS is more difficult to occur at grain boundaries with rather low Sigma value than at random grain boundary. It is also shown that, for random grain boundary, GBS is easier to occur at a grain boundary with higher angle.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

The stress corrosion cracking (SCC) of Type 304L stainless steel in chloride solutions containing various concentrations of thiosulfate ions (S2O3 2-) has been studied by using a slow strain rate testing apparatus with a dynamic observation system. It was observed that intergranular cracks were initiated from pits and propagated with the evolution of bubbles. The SCC was found to occur &gt
10-3 M S2O3 2-, and the variation in the concentration of S2O3 2- from 10-3 to 10-1 M did not shown any marked difference in SCC susceptibility evaluated by maximum stress. According to the analysis of the cracking behavior from the observed images, crack propagation rate was found to increase slightly with increase in the concentration of S2O3 2-. The increase is considered to be caused by the change in the corrosion potential with the concentration. Apparent critical stress intensity factor for SCC was less scattered around 2-3 MNm-3/2 and slightly increased with increase in the concentration. The strain where either a pit or a crack was initiated first and the number of pits and cracks decreased remarkably and increased with increase in the concentration, respectively. S2O3 2- mainly affects the initiation process of the pit and the crack more than the crack propagation process. © 1997 Elsevier Science Ltd.

DOI： 10.1016/S0010-938X(97)00087-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

The stress corrosion cracking (SCC) of Type 304L stainless steel in chloride solutions containing various concentrations of thiosulfate ions (S2O3 2-) has been studied by using a slow strain rate testing apparatus with a dynamic observation system. It was observed that intergranular cracks were initiated from pits and propagated with the evolution of bubbles. The SCC was found to occur &gt
10-3 M S2O3 2-, and the variation in the concentration of S2O3 2- from 10-3 to 10-1 M did not shown any marked difference in SCC susceptibility evaluated by maximum stress. According to the analysis of the cracking behavior from the observed images, crack propagation rate was found to increase slightly with increase in the concentration of S2O3 2-. The increase is considered to be caused by the change in the corrosion potential with the concentration. Apparent critical stress intensity factor for SCC was less scattered around 2-3 MNm-3/2 and slightly increased with increase in the concentration. The strain where either a pit or a crack was initiated first and the number of pits and cracks decreased remarkably and increased with increase in the concentration, respectively. S2O3 2- mainly affects the initiation process of the pit and the crack more than the crack propagation process. © 1997 Elsevier Science Ltd.

DOI： 10.1016/S0010-938X(97)00087-5

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

The effect of crystallization on the stochastic pit generation process of an Fe-Cr-Si-B amorphous alloy in a berate solution containing Cl- ions has been analyzed. Fitting potential of amorphous alloys showed a wide scatter and mean value shifts to the noble direction before crystallization starts, decreasing rapidly after crystallization, Stochastic analysis demonstrates that the initial increase in pitting potential is brought about by an increase in the pit repassivation rate, while the decrease in pitting potential after crystallization is caused by a rapid increase in the pit generation rate. Silicon oxide film formation during the heat treatment is concluded to be the main reason to increase the pitting potential and alpha-Fe micro-crystallites by crystallization in the latter stage of the heat treatment are responsible to decrease the pitting potential.

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記述言語：日本語   出版者・発行元：Japan Society of Corrosion Engineering  

The effects of potential and sodium sulfate concentration on the initiation and growth of IGSCC of sensitized 304 stainless steel in 0.01-1kmol/m³ sodium sulfate solutions at 368K have been investigated. A slow strain rate test apparatus was used to make direct observations of crack generation and propagation during the test. The initiation and growth of IGSCC were found to occur for potentials from -500mV_Ag/AgCl to -200mV_Ag/AgCl and the IGSCC susceptibility reached a maximum at approximately from -400mV_Ag/AgCl to -300mV_Ag/AgCl. The initial crack generation time was a minimum around -400mV_Ag/AgCl and the crack growth rate increased monotonously with increasing potential. Therefore, the SCC test results indicated that the maximum IGSCC susceptibility emerged at approximately from -400mV_Ag/AgCl to -300mV_Ag/AgCl, suggesting that the susceptibility of IGSCC must be determined as a function of the synergistic effect of the crack generation frequency and the crack growth rate. The initial crack generation time decreased with increasing sodium sulfate concentration. The crack growth rate was independent of the crack generation time and showed approximately a constant value. The crack generation time were distributed at random. Therefore, it was considered indispensable to evaluate IGSCC resistance of various austenitic stainless steel by statistical methods.

DOI： 10.3323/jcorr1991.44.343

CiNii Books

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00033423074?from=CiNii

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IRON STEEL INST JAPAN KEIDANREN KAIKAN  

The amount of defects in TiN films coated on SUS 304 stainless steel has been evaluated by three electrochemical measuring techniques in a sulfuric acid solution containing potassium thiocyanate. Three different TiN films were prepared by a hollow cathode ion plating technique. A critical passivation current density (i(crit)) can readily provide the apparent amount of the defects. However, this method was found to overestimate the amount of the defects because active dissolution of the substrate at the measurement caused enlargement of the defects. An activation time, which is a period until free corrosion potential (E(corr)) descends to that of the bare substrate steel, was not useful to evaluate the amount of defects rapid ly because about a half the specimens did not activate within a test time of 90 ks. More precise and less destructive evaluation could be achieved by using a reciprocal of polarization resistance (R(p)(-1)) which was obtained by an electrochemical impedance spectroscopy immediately after activation. It is concluded that i(crit) is a suitable parameter for an approximate estimation of the defect area, and R(p)(-1) provides the more precise amount of the original defects.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ASSN CORROSION ENG  

The initiation and growth of cracks in type 316L (UNS S31603) stainless steel (SS) in a chloride solution containing thiosulfate ions (S2O32-) during slow strain rate testing (SSRT) were analyzed on the basis of fracture mechanics. Crack behavior on the specimen surface was observed in situ using a charge-coupled device (CCD) camera with a videotape recording system. Three types of specimens were used: a single-notched plate, a smooth cylinder, and a smooth plate. The single-notched specimen failed to produce a sharp crack similar to that formed on the smooth specimens. For the smooth specimens, the stress intensify factor (K-ISCC) was found to vary from 3.9 MN/m(3/2) to 5.0 MN/m(3/2), and the crack growth rate ranged from 5.2 x 10(-9) m/s to 1.0 x 10(-8) m/s, which approximately agreed with data determined by other authors using a fracture mechanics approach. Thus, the SSRT combined with the in situ observation technique was useful in analyzing the crack initiation and growth process.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

(Rec.1993.8.18)

DOI： 10.3323/jcorr1991.43.331

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(Rec.1992.8.25)

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(Rec.1992.9.9)

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATL ASSN CORROSION ENG  

Thiosulfate ion was used as a substitute for hydrogen sulfide (H2S) to simulate stress corrosion cracking (SCC) of corrosion-resistant alloys (CRAs) and sulfide stress cracking (SSC) of high-strength, low-alloy steels. Several SCC tests using a variety of stress application techniques showed the brine containing thiosulfate exhibited similar severity to brine containing H2S in regard to SCC when plastic strain was applied to the CRAs. Materials that exhibited SCC susceptibility in brine containing thiosulfate agreed well the SCC susceptibility of those in brine containing H2S. Types 304 (UNS S30400) and 316L (UNS S31603) stainless steels and duplex stainless steel exhibited in both environments. However, high-nickel austenitic alloys such as alloys 904L (UNS N08904) and 825 (UNS N08825) did not. A 10(-3) to 10(-2) mol/l S2O32- addition in 20% NaCl aqueous solution at 353 K corresponded to H2S of 0.1 to 1 MPa at 473 K. The SSC susceptibilities of high-strength, low-alloy steels in a 10(-3) mol/l S2O32- + 5% NaCl + 0.5% acetic acid solutions were close to those in NACE Standard TM0284-86 solution (substitute ocean water saturated with 0.1 MPa H2S). Results suggested the possibility of using thiosulfate ion as an alternative to H2S.

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(Rec.1992.8.8)

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(Rec.1992.6.4)

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(Rec.1991.7.16)

DOI： 10.3323/jcorr1991.41.217

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JAPAN INST METALS  

It is well known that grain boundary sliding (GBS) mainly contributes to superplastic deformation. However, since there are few studies on GBS behavior at each grain boundary during superplastic deformation by using polycrystal material, the contribution of three grain boundary characters to GBS at each grain boundary during superplastic deformation has been investigated. Three characters were adopted as the following; the angle between grain boundary at the specimen surface and tensile direction, the kind of adjacent grains across a grain boundary, and SIGMA-value which was calculated from orientations of adjacent grains across a grain boundary. The examination was carried out by tensile test in SEM with Pb-Sn eutectic alloy at room temperature. The results obtained are summarized as follows: (1) The superplastic behavior was confirmed to occur when GBS was observed at most of grain boundaries. (2) It is considered that GBS is easier at a grain boundary both with the higher angle between grain boundary and tensile direction, and with the same kind of adjacent grains across a grain boundary. (3) So far as Pb-Pb boundary is concerned, GBS was more difficult to occur at grain boundary with rather low SIGMA-value than at random grain boundary. Moreover, for random grain boundary, GBS was easier to occur at a grain boundary with higher angle of grain boundary.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(Rec.1991.3.25)

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

(Rec.1990.11.19)

Web of Science

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(Rec.1989.8.30)

DOI： 10.3323/jcorr1974.39.6_303

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

Localized corrosion behavior of welds of type 304 stainless steel was investigated by using a scanning vibrating electrode technique in H2SO4 aqueous solutions containing various concentrations of KSCN at 298 K. The distribution of corrosion current density was measured during an electrochemical potentiokinetic reactivation test in 0.5 mol/l H2SO4 solution containing 10-2 mol/l KSCN. The weld metal, heat affected zone, and base metal can be distinguished for differences in the current density at the transition potential from passive to active region. The distributions of current density were measured during immersion in 0.5 mol/l H2SO4 solutions containing various concentrations of KSCN. The weld metal shows anodic peak current density at 10-4 mol/l KSCN, whereas it shows a cathodic peak current density at 100 mol/l KSCN.

DOI： 10.3323/jcorr1974.39.6_303

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DOI： 10.3323/jcorr.67.2

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DOI： 10.11457/swsj.71.1_11

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DOI： 10.2464/jilm.65.416

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DOI： 10.3323/jcorr.63.309

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DOI： 10.3323/jcorr.63.76

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DOI： 10.3323/jcorr1991.47.78

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DOI： 10.2320/materia.36.311

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記述言語：日本語  

CiNii Books

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記述言語：日本語  

CiNii Books

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記述言語：日本語  

CiNii Books

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記述言語：日本語  

CiNii Books

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記述言語：日本語   出版者・発行元：腐食防食協会  

CiNii Books

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