METHOD OF APPLYING LUBRICANT ON MANDREL BAR, METHOD OF CONTROLLING FILM THICKNESS OF LUBRICANT ON MANDREL BAR, AND METHOD OF MANUFACTURING SEAMLESS STEEL TUBE

摘要

PROBLEM TO BE SOLVED: To provide a stably high-quality seamless steel tube capable of preventing occurrence of seizing marks and internal flaws. SOLUTION: In the method of applying a lubricant on a mandrel bar, the film thickness of the lubricant is decided from a predetermined master curve of the amount of mica and the film thickness of the lubricant when applying a nongraphitic lubricant composed of, by mass, the oxide layered compound of 10-70% and baric acid of 30-90% to a mandrel bar. In the method of manufacturing the seamless steel tube, the seamless steel tube is manufactured by using the mandrel bar on which the lubricant is applied by the method. COPYRIGHT: (C)2008,JPO&INPIT