Causes of black spots on the surface of steel strip
Release time:
2022-06-23
The main reason for the black spots on the surface of cold-rolled strip steel is that the emulsion is not clean enough, so black spots will be produced after annealing.
The main reason for the black spots on the surface of cold-rolled strip steel is that the emulsion is not clean enough, so black spots will be produced after annealing.
Cause of Black Spot on Strip Surface
1. Strip surface roughness: If the surface roughness is obvious, the gap between the steel coil layer and the layer interface is large, which is conducive to the volatilization of the emulsion.
2. Annealing substrate cold hard coil type: The evaporation of emulsion during annealing heating will seriously affect the quality of cold hard coil. If there is a wave in the strip steel, it will also have a certain impact on the volatilization of the interlayer emulsion.
3. Residual chloride ions on the surface of the strip steel: If it is not clean during rinsing, chloride ions will remain on the surface of the strip steel, causing electrochemical corrosion and producing black Fe 304.
4. Emulsion volatility: high-quality emulsified heat volatilization can reduce the shortcomings of cold rolled black spots.
5. The rolling tension of the finished product: reduce the winding tension, the gap between the winding layers, so that the distance between the rolling layers flows and is fully volatilized and emulsified.
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