The pitting of the quilting tube is characterized by the uneven surface of the product, which is also called the rough surface. More continuous into pieces, there are also local or periodic distribution. The causes of pitting are:
1. The groove of the finished hole or the front hole of the finished product is worn, or the broken iron oxide scale is stuck;
2. The broken iron oxide scale is pressed into the surface of the rolled piece and then comes off;
3. Corrosion of the roller;
4. The surface of the billet is seriously oxidized during the heating process.