5.2.Cut end
Photo-11 shows early corroded conditions of the cut end of W.R.Alstar, 55% Al-Zn and Galvanized.
Since W.R.Alstar, unlike Galvanized, does not have much of the sacrificial corrosion, red rust develops in a short time. In this respect, 55% Al-Zn alloy and Galvanized are superior. However, as discussed under 4.3-Atmospheric exposure tests, W.R.Alstar is superior in respect to long-term corrosion resistance at the cut end.

Photo-11. Corroded conditions of the cut end of W.R.Alstar, 55% Al-Zn and Galvanized

Photo-12 shows XMA analysis of the cut end of W.R.Alstar after 10-year atmospheric exposure tests in Singapore. As shown therein, "Fe oxide" has developed at the cut end but further outside, a unique structure is noted, in which corrosive growth of Al, S and O provides a cover. it indicate that, as a result, red rust developed at the ends in early periods of exposure is covered with Al liquating out with the corrosion of the coating layer and that such corrosive growth is unlikely to liquate out in the atmospheric environment, which works to shield corrosive agents and suppress corrosion of the substrate.
Because of this reason, in W.R.Alstar the progress of corrosion from the cut end is very slow even after an extended period of time. The same thing may be said of Type 2 (pure aluminum type).
Photo-13 shows XMA analysis of the cut end of 55% Al-Zn under atmospheric exposure tests in Singapore. As shown therein, "Fe oxide" has developed at the cut end but further outside, a unique structure is noted, in which corrosive growth of Al, Zn, S and O provides a cover. Because of this reason, in 55% Al-Zn the progress of corrosion from the cut end is very slow. However, when W.R.Alstar and 55% AI-Zn are compared, coatings remaining near the ends are different and W.R.Alstar is judged to have better long-term corrosion resistance properties.

Fig. 4 and 5 are sketches depicting changes noted on the cut ends of W.R.Alstar and 55% Al-Zn over certain lengths of time.



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