| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for minimizing the inside surface flaws of a steel pipe obtained by regulating the relationship between the distribution form and amount of the porosities of a round steel billet which must be controlled by various factors, such as at the time of draft in drawing in continuous casting, at the time of heating for the purpose of blooming and at the time of blooming and the inside surface flaws. SOLUTION: The method for manufacturing the hot rolled seamless steel pipe having minimized inside surface flaws from the round steel billet 1 having a diameter D by a Mannesmann method comprises utilizing ultrasonic flaw detection of supplying the round steel billet 1 where the porosities detected by the ultrasonic flaw detection are distributed as material to a piercer 3 within the range of d1 (where d1≤0.4d) in the central part when the diameter of a plug 4 used in the piercer 3 is defined as d and piercing the round steel billet by piercing and rolling. COPYRIGHT: (C)2005,JPO&NCIPI
|
