1. Cracks:
It is generally straight, occasionally curved, extending to the surface of the product vertically, horizontally or at a certain angle, and its length varies. Causes: Steelmaking reasons (microcracks, subcutaneous air bubbles, scars and pits on the surface of billets, etc.); Steel rolling reasons (unreasonable heating and rolling process, roll surface wear, excessive roughness or surface scratches, rough rolling guides scratches, mishandling, etc.). Will cause cracks on the surface of the product. Its inspection method: relatively large ones can be seen directly with the naked eye, and general cracks can be manually torsion test method (small specification).
2. Fold:
Surface defects that are straight or jagged thin lines on the surface along the rolling line direction, and knuckles on the cross section. May be continuous or discontinuous, warped when twisted. Causes: The billet itself has defects such as shrinkage cavity, segregation, and inclusions; the pass is overfilled or underfilled, and the opening of the guide is too large, so that the rolled piece swings back and forth to produce irregular ears, causing irregular folding; If the guide is not centered or one guide wheel does not rotate, it will cause one-sided folding. Most of the folds caused by guide defects occur in the first few passes of the finished product. The reason for the intermittent folding of the finished product is that there is a problem with the shape of the intermediate rolling and pre-finishing rolling (too large) or the opening of the inlet guide is too large. Carefully check the material shape and size of each stand, the degree of wear of the rolling groove and the opening of the guide, and pay attention to observe whether there is steel inversion in the rough and medium rolling.
3. Flower injury:
Scratches are shaped like grooves and are distributed longitudinally along the wire. Causes: Scratched by sharp objects (“sticky steel” on the guide, other sundries or poor processing of the guide, wear, cracks, burrs will scratch the rolled piece, the guide groove of the water cooling section, the spinning tube other sundries or bumps in the
4. Scarring:
There are appendages on the surface that can be removed, which are generally brought by raw materials, or caused by the loss of meat from the front rolling groove or roll ring, and other small sundries brought in during the rolling process. If there is intermittent scabbing, the front groove or roll ring has lost flesh, and in this case, carefully check the surface of the roll groove and roll ring.
5. Roll printing:
Bumpy, usually periodic, variable in shape and size. Cause: The roller ring or the pinch roller has sunken damage or the roller ring is cracked.
6. Pockmarked noodles:
On the surface, there are defects in the flake distribution composed of continuous irregular fine concave-convex points. The roller rings of the finished sorting or the pre-finished sorting are seriously worn.
