Macula

Defect Name: macula < br / > definition and appearance: < br / > generally distributed in the middle of the strip steel, symmetrically distributed on the upper and lower surfaces of the strip steel, in yellow, one or more strips are distributed in strips, and seriously run through the whole length of the strip steel; At present, it only occurs when the galvanizing line is used as the sub winding line. < br / > causes: < br / > the formation conditions and appearance are special, which is a kind of dot diffusion corrosion under the condition of insufficient oxidation< Br / > hazard: affect the appearance quality of steel strip and the processing and use of users< Br / > prevention and elimination methods: < br / > ● reduce the acid rolling coiling tension as much as possible< Br / > ● ensure sufficient cooling time after annealing< Br / > ● ensure that the purging device of the temper mill works well< Br / > ● shorten the residence time of steel coil between processes< Br / > inspection and judgment: < br / > ● visual inspection< Br / > ● slight macular (light yellow) can be judged as qualified product (S4), and serious macular can be judged as unqualified product. < br / >