To propose a lubricant for warm pressing, suitable for pressing in warm temperatures and capable of suppressing a roll flaw using even a small amount of lubricant, and a method for producing a welded steel pipe, scarcely causing flaw in forming of an open pipe.
This method for producing a welded steel pipe comprises forming an open pipe while feeding, in an amount of 10 to 2,000 ml/min, a lubricant composed of water containing one or more kinds of compounds selected from boron oxide, boric acid and boric acid compound and a water-soluble polymer or a solution composed mainly of water and containing these above compounds and the water-soluble polymer to a forming roll and heating both edges of the open pipe and putting both edges together and joining both edges by a squeeze roll, when preheating a band steel in a warm area and continuously forming the welded steel pipe by the forming roll.
OKABE YOSHITOMO
ITAYA MOTOAKI
HASHIMOTO YUJI
