Black spot
From：
Gaoming Foundation Date：12-22 3523 Belong to：Cold rolling knowledge
Defect Name: black spot
definition and appearance:
black spot is the emulsion spot produced by acid rolling. After annealing and reduction, the surface area carbon is generally distributed in the middle part of the strip, which is symmetrical distributed on the upper and lower surfaces of the steel strip, and is black, with one or more strips distributed, and the full length of the penetrated strip; nbsp;
< br / > causes: < br / > ● the emulsion is not purged completely< Br / > ● the surface temperature of the strip is too low< Br / > ● strip surface water erosion< Br / > ● the anti rust ability of emulsion is insufficient; Hazard: < br / > affect the appearance quality of steel strip and the processing and use of users< Br / > prevention and elimination methods: < br / > ● strengthen purging< Br / > ● control the surface temperature of the strip< Br / > inspection and judgment: < br / > ● visual inspection< Br / > ● slight black spots are allowed locally, but serious or penetrating the whole length must be judged by grade< br/>
definition and appearance:
black spot is the emulsion spot produced by acid rolling. After annealing and reduction, the surface area carbon is generally distributed in the middle part of the strip, which is symmetrical distributed on the upper and lower surfaces of the steel strip, and is black, with one or more strips distributed, and the full length of the penetrated strip; nbsp;
< br / > causes: < br / > ● the emulsion is not purged completely< Br / > ● the surface temperature of the strip is too low< Br / > ● strip surface water erosion< Br / > ● the anti rust ability of emulsion is insufficient; Hazard: < br / > affect the appearance quality of steel strip and the processing and use of users< Br / > prevention and elimination methods: < br / > ● strengthen purging< Br / > ● control the surface temperature of the strip< Br / > inspection and judgment: < br / > ● visual inspection< Br / > ● slight black spots are allowed locally, but serious or penetrating the whole length must be judged by grade< br/>
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