| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a blackened galvanized steel sheet having a uniform hue by forming a specified zinc phosphate film on the surface of a steel sheet and specifying its relative intensity and the difference in the indexes of brightness. SOLUTION: A galvanizing layer is formed on the surface of a steel sheet. On the surface of this galvanizing layer, a zinc phosphate film is formed by the coating weight of 1 to 4g/m<2> , and as for this film, the relative intensity W calculated by the formula I lies in the range of 40 to 70%, and it has a stable hue in which the difference in the indexes of brightnessΔL is regulated to <=4. In the formula I, I (020) denotes the X-ray diffraction intensity of the (020) plane (d=9.16Å), I (011) denotes the X-ray diffraction intensity of the (011) plane (d=4.85Å), I (040) denotes the X-ray diffraction intensity of the (040) plane, (d=4.57Å), I (111) denotes the X-ray diffraction intensity of the (111) plane (d=4.41Å), I (240) denotes the X-ray diffraction intensity of the (240) plane (d=3.46Å), I (221) denotes the X-ray diffraction intensity of the (221) plane (d=3.39Å) and I (311.241) denotes the X-ray diffraction intensity of the (311.241) plane (d=2.85Å). In this way, the blackened galvanized steel sheet suitable as the material for facing such as a roof material or the like in which designing properties are particularly regarded as important can be obtd.
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