CORROSION ENGINEERING
Online ISSN : 1884-1155
Print ISSN : 0010-9355
Volume 33, Issue 1
Displaying 1-7 of 7 articles from this issue
  • Hachiro Imai, Ichiro Fukumoto
    1984 Volume 33 Issue 1 Pages 3-10
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    The effect of Sn addition on the corrosion resistance of 25Cr-6Ni duplex steel has been studied. Results obtained were summarized as follows.
    (1), Corrosion rate of 25Cr-6Ni steel was decreased with small amounts of Sn addition in 5wt% H2SO4 solution at boiling temperature. (2), By addition of SnSO4 in 5wt% H2SO4 at boiling temperature, the corrosion rate of 25Cr-6Ni steel was reduced. (3), Alloying of Sn made the passivation potential, Ep, less noble and reduced the critical current density, Icr, in 5wt% H2SO4 solution. (4), Alloying of Sn had no influence on the corrosion rate in 65wt% HNO3 solution except the case Sn bearing steels were reheated at 1200°C. In these reheated steels, the suscepitability of intergranular corrosion was increased with ferrite amounts. (5), Alloying of Sn had no effect in improving the corrosion rate of 25Cr-6Ni steel in 50g/l·FeCl3+1/20N·HCl solution at 50°C and 70°C. In addition the pitting potential, Vc, was slightly more noble by Sn addition of 25Cr-6Ni steel in 0.5mol/l NaCl solution at 30°C.
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  • Masaharu Nakamori, Yoshio Harada
    1984 Volume 33 Issue 1 Pages 11-18
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    High temperature corrosion of SUS 316, similar in morphology to that occurred at the actual transition joint in boilers, was albe to be reproduced with 80%Na2SO4-20%V2O5 synthetic ash coating and simulated combustion gas at 600°C. SUS 316 showed the poorest corrosion resistance among the tested 3 types of stainless steels (SUS 316, 321 and 347).
    The poor resistance of SUS 316 is likely to be due to the effect of Mo in the steel, the formation of oxide scale with many defects on the surface of carburized base metal, and its cracking and flaking off by the thermal stress induced by the change of boiler load.
    STBA 24 was corroded rapidly at the first stage but the oxide scale formed on this steel at 600°C was thick and compact, and thus showed good corrosion protective ability in the long run.
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  • Hiroshi Sakata, Yuuichi Ishikawa, Toshinori Ozaki
    1984 Volume 33 Issue 1 Pages 19-23
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    The present paper concerns with the evaluation method of localized corrosion life of fin materials (aluminum and copper) used for air cooled heat exchangers. Cyclic dry-wet corrosion tests were performed in a laboratory, in which component models were exposed to the condition simulating the service condition of the component. Moreover, field exposure tests of component models were performed. Comparing with the two tests, the acceleration factor of the laboratory tests was determined. It turns out that the corrosion feature of the fin materials was localized corrosion, such as pitting corrosion, associated with general corrosion. Corrosion damage of fin materials was evaluated by tensile tests and the statistical distribution of the test results was discussed in terms of the model developed on the basis of the fracture mechanism. Scanning electron microscopic observations indicated that the fracture of fin materials occurred at the root of the pit and the statistical distribution of the tensile test data was well described by the weakest link model. Thus, the corrosion lives of the fin materials were estimated by means of the extreme value statistical analysis and the results were in good agreement with the actual localized corrosion data obtained from some operating machine components.
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  • Kiyoshi Kiuchi, Saburo Shimodaira
    1984 Volume 33 Issue 1 Pages 24-32
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    Effect of nickel content on SCC susceptibility of 23% Cr stainless steels in boiling 42% MgCl2 solution was examined by SSRT technique. Corrosion behavior was studied by performing electrochemical potential measurement, XPS analysis of surface films and the quantitative analysis of the elements dissolved during the exposure tests. Susceptiblity to TGSCC increased significantly with increasing nickel contents within the single α phase region up to 3% Ni. Such tendency agreed well with that of the formation of passive film. The principal role of nickel on the corrosion process is believed to be the enhancement of the formation of passive film enriched chromium. Nickel was found to have accumulated in the interface between the passive film and the undering alloy. The similar role of nickel was observed in results tested in solution dissolved Ni2+ and Cr6+ ions. Change in the properties of passive film rather than that in mechanisms of plastic deformation of alloys with increasing nickel content is considered to be a dominant factor in the TGSCC of ferritic stainless steels. With Ni contents above 4%, the increase of resistance to SCC by forming duplex phase is interpreted as the results of the selective deformation of austenite and crack arresting due to enhanced attack in the ferrite phase assisted by the cathodic action of austenite phase.
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  • Eiji Kikuchi, Noriyuki Ohnaka, Akira Minato
    1984 Volume 33 Issue 1 Pages 33-36
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    The effect of hydrogen peroxide on the stress corrosion cracking (SCC) of sensitized Type 304 stainless steel was studied in water containing various amounts of dissolved oxygen at 150°C by cyclic slow strain rate tests. It was found that the intergranular SCC by dissolved oxygen was effectively inhibited by the addition of hydrogen peroxide, and its concentration required for preventing the SCC increased with increasing the concentration of dissolved oxygen in the water.
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  • Akio Furuya
    1984 Volume 33 Issue 1 Pages 37-46
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
    Mechanisum and evaluation of degradation of paint films are reviewed. Characterization by surface analytical techniques such as FT-IR, ESCA are useful for estimation of durability of paint films.
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  • Teiichi HOMMA
    1984 Volume 33 Issue 1 Pages 50-51
    Published: January 15, 1984
    Released on J-STAGE: October 30, 2009
    JOURNAL FREE ACCESS
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