Zairyo-to-Kankyo
New Arrival Alert : OFF

You can use this feature after you logged into the site.
Please click the button below.

Log in / Sign up
ONLINE ISSN: 1881-9664
PRINT ISSN: 0917-0480

Zairyo-to-Kankyo Vol. 44 (1995), No. 6

  • Analysis of Corrosion Damage on Water Tap

    pp. 336-342

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    Most of the water taps for domestic use are made of copper alloys. Their valve seats occasionally suffer damage due to corrosion and erosion as a result of water quality and seemingly cavitation respectively. The examination of damage mechanism and the development of testing methodology for selecting the durable materials to the attack were requested. In order to understand and solve these problems completely, erosion-corrosion tests were carried out on various copper alloys (five brasses and five bronzes) by using three test methods: (a) the ISO 6509 dezincification test for pure corrosion; (b) the vibratory cavitation test with eccentric stationary specimen for cavitation erosion-corrosion; and (c) the Jet-in-Slit test for flow induced localized corrosion. The materials tested were ranked in different orders of merit according to the results obtained in the three test methods. Among these rankings, the one obtained in the Jet-in-Slit test has agreed upon with the ranking order that had been determined by experiences of field engineers who engaged themselves with the troubles under practical conditions. Hence it was concluded that the damage on valve seats has been caused by the flow induced localized corrosion, and the Jet-in-Slit was recommended as the reliable test method in selecting durable valve seat materials.
  • The Effect of Potential on Initiation and Growth of Intergranular Stress Corrosion Cracking of Sensitized 304 Stainless Steel in Dilute Sodium Sulfate Solutions at 368K

    pp. 343-349

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    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 -500mVAg/AgCl to -200mVAg/AgCl and the IGSCC susceptibility reached a maximum at approximately from -400mVAg/AgCl to -300mVAg/AgCl. The initial crack generation time was a minimum around -400mVAg/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 -400mVAg/AgCl to -300mVAg/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.
  • Electrochemical Evaluation of Pinhole Defects in TiN-Coated Stainless Steels

    pp. 350-354

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    Pinhole defects of TiN coated stainless steels were evaluated electrochemically in deaerated 0.5kmol⋅m-3 H2SO4+0.05kmol⋅m-3 KSCN solution at 298K. The TiN films formed by an activated reactive evapolation method exhibited the columnar structure with ‹111› orientation, which contained more or less pinhole defects. The critical current density for passivation, icrit, in the TiN-coated stainless steels decreased with an increasing film thickness, and the resulting corrosion resistance was improved remarkably by TiN-coating. The area fraction of pinhole defects was evaluated by the ratio of icrit of a coated and a non-coated specimen. Thus, the result coincided well with the ‘true’ area fraction based on the optical micrographs before or after polarized anodically. Consequently, such electrochemical measurement is superior as an evaluation method for the pinhole defects of corrosion-resistible coating.
  • Effect of Environmental Factors on Ennobled Electrode Potential attained in Natural Sea Water for Stainless Steels

    pp. 355-363

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    When stainless steels are immersed in natural sea water, biofilm begins to develop on their surface to make electrode potential (Esp) of the steels ennobled up to approximately 400mV vs. SCE, which enhances possibility of localized corrosion. In this paper, effect of environmental factors on activity of biofilm on the steels in natural sea water was investigated. Firstly, steels were immersed in natural sea water for 14-16 or 30 days from 1991 to 1994 to measure Esp vs. time of steels in various seasons. Attained value of Esp in winter was lower than that in the other seasons. Under conditions where sunlight was allowed to illuminate steels, Esp decreased by about 100mV around noon every day and returned to their stationary ennobled value at night. This effect of sunlight was observed for 316 steels with Esp values more noble than 200mV vs. SCE. Different from sunlight, a fluorescent lamp for cultivating plants made no significant effect for the Esp. Therefore, following experiments were carried out under the condition of turning on the lamp. To study effect of other environmental factors on activity of biofilm, ennobled steels were immersed in abiotic sea water adjusted to various temperatures (5-95°C), pH (2-10), salinities (3-45‰) or applied potentials (-500-300mV vs. SCE). As the next step of experiments, the samples were transfered to abiotic sea water under natural condition and subsequent behavior of Esp was measured to examine whether Esp of them were maintained after these treatments. Ennobled Esp of the steels was not maintained in abiotic sea water adjusted to temperatures higher than 60°C for 24 hours, pH 2 and 3 for 24 hours, salinity of 45‰ for 96 hours or applied potential of -500mV vs. SCE for 5 hours.
  • Corrosion of Electric Materials

    pp. 364-369

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    Various electric materials applied in computers and peripherals are used under sever atmospheric environment, which is the cause of atmospheric corrosion related with humidity and various additional factors. So, these materials corrode and electric systems take damages such as electric-shorts, electric-disconnection. In this paper, we review some examples related with atmospheric corrosion factors as the effect of air polutant gases, the degases from plastic materials and so on.
  • High Temperature Oxidation of Metals (1)

    pp. 370-370

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up

Article Access Ranking

27 Jun. (Last 30 Days)

  1. Perspective toward Long-term Global Goal for Carbon Dioxide Mitigation in Steel Industry Tetsu-to-Hagané Vol.105(2019), No.6
  2. Hydrogen Embrittlement Susceptibility Evaluation of Tempered Martensitic Steels Showing Different Fracture Surface Morphologies ISIJ International Advance Publication
  3. Production and Technology of Iron and Steel in Japan during 2018 ISIJ International Vol.59(2019), No.6
  4. Effect of a Zn Interlayer on the Adhesion Strength and Corrosion Resistance of Zn–Mg Coated TRIP Steel ISIJ International Vol.59(2019), No.6
  5. Fundamentals of Silico-Ferrite of Calcium and Aluminium (SFCA) Iron Ore Sinter Bonding Phase Formation: Effects of Titanium on Crystallisation during Cooling ISIJ International Vol.59(2019), No.6
  6. A Kinetic Model of Mass Transfer and Chemical Reactions at a Steel/Slag Interface under Effect of Interfacial Tensions ISIJ International Vol.59(2019), No.5
  7. Evaluation of the Structure and Strength of Coke with HPC Binder under Various Preparation Conditions ISIJ International Advance Publication
  8. Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation ISIJ International Advance Publication
  9. Evolution Mechanism of Inclusions in H13 Steel with Rare Earth Magnesium Alloy Addition ISIJ International Advance Publication
  10. Continuous Process of Pig Ironmaking using Focused Microwave Beams at 2.45 GHz ISIJ International Vol.59(2019), No.6

Search Phrase Ranking

27 Jun. (Last 30 Days)

  1. blast furnace
  2. blast furnace permeability
  3. blast furnace productivity
  4. phosphate treatment
  5. assimilation
  6. balling index
  7. bubbling ladle
  8. inclusions
  9. isij xafs
  10. lme