Cold rolled 304 stainless steel wire defects are microscopic "grooves". The line defect "groove" is lower than the surface of the normal rolled steel plate. The bottom and side surfaces of the line defect "groove" are rough and uneven, and its ability to emit light is low, and it is dark to the naked eye; the edge of the line defect groove There is a folded layer or a spread layer, the grains of the folded layer or the spread layer are smaller than those in the normal position, and at the tail of the line defect, the area of the spread layer increases, and the spread layer of fine grains appears in the local field of view, covering the entire trench groove.
The defect of 304 cold-rolled stainless steel wire is mainly due to the high local ferrite content in the continuous casting slab, and local micro-cracks are generated in the hot rolling deformation of the two-phase region, and the micro-cracks exposed on the surface of the billet are oxidized to form oxidation. The film, which was not removed during hot rolling and pickling, was further extended and developed into linear defects during cold rolling.