The pits on a Hydraulic Honed Tube looks usually rough and uneven in the surface, in most cases appearing continuously in an area, sometimes partially or periodically. Here are some causes as below,
1.Roll groove abrasion of finish hole or pre-finish hole, or adhering fragments of ferric oxide;
2.Fragments of ferric oxide is rolled onto the surface and then falls off;
3.The rollers rust;
4.The surface of the material is oxidized badly during heating;
Solutions to remove such pits as below,
1.Check rollers and replace timely those with corrosion and abrasion;
2.Improve the material of rollers, keep good cooling of rolling groove and adopt process lubricant (for plastic working) to enhance the abrasion resistance of rolling groove;
3.Control heating operation of material, keep it positive in the furnace and reduce oxidizing gas; For some alloy steel that oxidizes easily and of which the oxide scale doesn’t fall off easily, take measures to put a steel sheet outside the processed material as a protection of heating;
4.Remove ferric oxide in the surface before the processing of rough rolling with high-pressure water, compressed air or steel brushes.
