METHOD FOR MANUFACTURING SEAMLESS METALLIC TUBE

摘要

PROBLEM TO BE SOLVED: To provide a manufacturing method of a seamless metallic tube by which the defective biting of a billet in a piercer is suppressed. SOLUTION: When a mill scale material is used as a round billet, the major axis (a) and the minor axis (b) in a region of at least twice length of the nominal outside diameter D from the end on the top side of rolling are measured and only the billet having the ratio (a/b) of <=1.03 is supplied to the piercer.