Hole

Defect Name: hole < br / > definition and appearance: < br / > hole is a defect of discontinuous material penetrating the upper and lower surfaces of the strip steel. During rolling, the internal part of the strip steel section is loose, and the stress at this place exceeds the deformation limit (such as plasticity) of the material. The hole is caused by material tearing. The thinner the strip steel is, the more obvious this phenomenon is& nbsp;  < Br / > causes: < br / > ● the steel is impure and the non-metallic inclusions in the cold rolled substrate are serious< Br / > ● there are scabs, bubbles, serious roll marks or loose internal structure on the surface of cold rolled substrate, which are exposed after cold rolling and extension to form perforation< Br / > ● foreign matter pressing in < br / > hazard: < br / > the steel strip with holes cannot be used < br / > prevention and elimination methods: < br / > ● strengthen steelmaking operation, reduce non-metallic inclusions and improve the purity of steel< Br / > ● strengthen the inspection of cold rolled substrates to prevent raw materials with scabs and indentation from being put into use< Br / > ● strengthen equipment management and remove foreign matters on equipment in contact with steel strip< Br / > inspection and judgment: < br / > ● visual inspection< Br / > ● individual holes are allowed at the tail of cold and hard roll, and holes are not allowed at other parts< br/>