Outline of program

The materials and the examination methods are discussed in detail in the corrosion data sheet technicaladvisory committee. The principle data includedin the data sheets are obtained using the standard test procedures specified in the appropriate Japan Industrial Standard (JIS), e.g. JIS Z 2381 (2001) “Recommended Practice for Weathering Test”, JISZ 2382 (1998) “Determination n of pollution forevaluation of corrosivity of atmospheres” and JIS Z2383 (1998) “Standard specimens of metals andalloys, Determination of corrosion rate of standard specimens for the evaluation of corrsivity ofatmosphers” , etc.

Material

The materials on the market and the melted alloys (discussed in the technical advisory committee), were supplied to the atmospheric corrosion test, of which manufacturing historys are clear.
The test pieces used are the plate, subjected to JIS Z 2381 (2001).

Examination method

The following examination methods in the atmospheric exposure tests were adopted.
  1. Opened exposure test (Refer to Figure 2) The test specimens are directly placed on the exposure flame under the natural environment suchas rain, wind, and solar radiation. The exposure testflames are inclined at an angle of 45 °from horizontalskyward-facing.
  2. Sheltered exposure test (Refer to Figure 3) The test specimens are placed on the covered exposure flame desigened horizontally, and the influences of rain and solar radiation to specimensare avoided.

Each Test is excuted at Tsukuba, Choshi and Miyakojima respectively. Positions and environmetal factors of each test site are shown in Fig.4 and Table3, respectively.

Evaluation items

The test piece collected after a prescribed the exposure period is evaluated by the following items.
  1. External observation After observing the externals of exposed specimens, photographs of both skyward-facing and groundward-facing of the test specimen are taken respectively.
  2. Cross-section observation Parts of the exposed test pieces buried in epoxy resin are observed the cross-section of rusts after polishing.
  3. Mass measurement
    1. Initial weight
      The mass of the test piece is measured bythe unit of mg order.
      The test pieces are stored under non-corrosive condition untill examination.
    2. Weight of the base metal after exposure test
      Corrosion puroducts are removed from the exposed test pieces by the process of JIS Z 2383 or ISO 8407. After this removal process, the mass of the test piece is measured by theunit of mg order.
    3. Corrosion rate
      Corrosion rate of the test piece is calculated according to the following equation.
      • r corr (mm/yrs) = Dm/(A ・r ・t)・10 where, Dm : weight loss (mg)
      • A : surface area of test piece (cm 2 )
      • r : density of test piece (g/cm 3 ) (The value of 7.86 is applied to all steel materials. )
      • t : exposure period (yrs)

Measurement of the weathering factors and environmental pollution factors

The weathering factors and the environmental pollution factors measured on each exposure siteare shown in Table 4.

The present program is specified as the first phase of the atmospheric corrosion data sheet work, and will revised as occasion demands. The test result are published in the NIMS Atmospheric Corrosion Data Sheet, indexed according to material specification or exposure period. The Atmospheric Corrosion Data Sheet describe, as a general rule, the primary data from the standard tests, as follows:

  1. Materials---Processing details, chemical compositions, heat treatments (if any), etc.
  2. Corrosion properties, Test conditions andspecimens, Metal loss-exposure period diagrametc.
  3. Weathering data at each exposure sites, etc.In addition to the Data Sheets, the publication of Interpretative Data Sheets (in Japanese) is intended.


In each processed and rearranged data extracted from several of Atmospheric Corrosion Data Sheets will be displayed in a comprehensive manner, along with some analysed results, photographs, analysis of the rust on the surface of exposed specimen and comments to assist in the direct application of the data in prctical situations.

It is evident that the DataSheets should be based on a background of advanced research activities. The results of studies have already been, or are going to be, reported in some scientific journals. It is believed that these research activities will contribute to the enhancement and future development of the Data Sheets, and thus to the progress of materials science.

Figure and Table


Fig.4 Positions of each exposure sites.


Table 3 Environmetal Factors of each exposure sites.
SiteTsukubaChoshiMiyakojima
EnvironmentsRuralRural/CoastalSubtropical Coastal
Latitude (North)36 °4'35 °43'24 °44'
Longitude (East)140 °7'140 °45'125 °19'
Air temperature (deg. C)*16.314.923.7
Relative humidity (%)*757881
Chloride deposition rate *0.0310.2910.325
* these values are average measued in 2000.


Table 4 Measurement of environmental factors.
Environment factorUnitExpression of results
Air temperaturedeg. CAverage per day
Average per month or year
Maximum of a day
Maximum of a month or a year
Minimun of a day
Minimum of a month or a year
Relative humidity%Average per day
Average per month
Minimun of a day
Minimum of a month or a year
Durations of sunshinehDurations of sunshine
Quantity of solar radiationMJ/m2Quantity of solar radiation of all heavens
Quantity of solar radiation of ultraviolet(0)°
Quantity of solar radiation of ultraviolet(45)°
PrecipitationmmPrecipitation
Precipitation timehPrecipitation time
Time of wetnesshTotal time of a a day
Direction of the wind16 azimuthsMaximum frequency of a day
Maximum frequency per month
Velocity of the windm/sAverage of a day
Average per month
SO 2 depositionr atemg/(m 2 d)Deposiotion rate per a day
Chloride deposition ratemg/(m 2 d)DEposition rate per a day