HIGH-ALLOY SEAMLESS STEEL PIPE MANUFACTURING METHOD

摘要

Pipe-swelling can be prevented by piercing-rolling a high-alloy steel billet heated to a temperature range from 900 to 1250°C with a piercing mill equipped with main rolls having a surface roughness R max of 150 to 500 µm. A ratio (the gap W G of guide rolls/the gap W R of the main rolls) is preferably at 1.10 to 1.20. The difference (¸ P - ¸ R ) is preferably set at 0 to 3.0°, where ¸ R is an angle between an exit-side face of each of the main rolls of the piercing mill and the pass line; and ¸ P is an angle between a rolling face of the piercing plug and the pass line.