| 摘要 |
PROBLEM TO BE SOLVED: To remarkably suppress a blackening phenomenon generated on a steel sheet during storing the minimized spangle hot dip galvanized steel sheet in a warehouse. SOLUTION: In this blackening resistant minimized spangle hot dip galvanized steel sheet, the intensity ratio in the (0004) plane is >=25, preferably >=40 wherein, the intensity ratio in the (0004) plane is calculated by performing X-ray diffraction by a diffractometer method (using a Cu tube sphere; the tube current: 40 mA; and the tube voltage: 150 kV) in the plated face to obtain the intensity (cps) in the (0004) plane of Zn, the intensity (cps) in the (10-10) plane of Zn, the intensity (cps) in the (10-11) plane of Zn and the intensity (cps) in the (10-12) plane of Zn and satisfying the formula, [the intensity ratio in the (0004) plane = the intensity in the (0004) plane×100/ the intensity in the (10-10) plane + the intensity of the (10-11) plane + the intensity in the (10-12) plane + the intensity in the (0004) plane}]. As the minimized treating solution, an aqueous solution in which 2 to 50 g/L ammonium chloride and 2 to 50 g/L disodium hydrogen phosphate are dissolved, and particularly, pH is controlled to 6 to 7 is suitable.
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