亜鉛鉄板のスパングルについて [in Japanese] Spangles of Galvanized Irons Sheet [in Japanese]
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It has been empirically known that corrosion resistance, formability, and other properties of the spangles of galvanized iron sheet greatly depend upon the variation of structural formation (general pattern) of the spangles. However, the reason of the fact has not been clarified yet.<br>The present study of the authors is an attempt to establish relations ammong external appearance, crystal orientation, and corrosion resistance of the spangles.<br>The results of the study revealed that with respect to external appearance, spangles would be divided into the following three types:<br>Type A (representative dendritic spangles): The spangle develops from one nucleus, and the main axes of growth linearly and radially extend with smaller branches growing out.<br>Type (B): The spangle grows from a nucleus in a straight line, and the axis of growth sharply divides the area into two parts: shiny area on one side and frosty one on the other.<br>Type (C): In this pattern, the axes of growth are generally curved and blurred, and more or less frosty areas are exhibited over the whole surface.<br>The results of the determination of crystal orientation of each spangle were as follows:<br>Type A: The crystal orientation on the plane parallel to the sheet surface was close to the basal plane of hexagonal crystals at an angle of not more than 8° to C-axis.<br>Type B: The crystal orientation on the plane parallel to the sheet surface was at an angle of 9-30° to C-axis. The shiny areas consisted of single crystals and the frosty ones exhibited progressive change of orientation with growth of the spangle.<br>Type C: The crystal orientation on the plane parallel to the sheet surface was at an angle of not less than 57° to C-axis. It was close to the hexagonal prism and consisted of polycrstals exhibiting preferred orientation.<br>As for corrosion resistanse, the spangles of Type A were superior to others. The corrosion resistance of the spangles was higher when the crystal orientation was closer to the basal plane of hexagonal crystals.
- Journal of the Metal Finishing Society of Japan
Journal of the Metal Finishing Society of Japan 24(1), 13-20, 1973
The Surface Finishing Society of Japan