Production manner of the high intensity steel sheet for the line flexible pipe above stretch strength 760MPa which suppresses the rise of the yield strength after the heating due to coat treatment and production mannered null mass of the high intensity metal tubing for the line flexible pipe which uses

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a high strength steel sheet having 760 MPa class tensile strength and excellent strain-aging characteristic and a method for producing a high strength steel tube using the above steel sheet.;SOLUTION: This method for producing the high strength steel sheet having 760 MPa class tensile strength and excellent strain-aging characteristic is performed as the followings: the steel composed by mass% of 0.01-0.5% C, 0.01-3.0% Si, 0.1-5.0% Mn, 0.03% P, 0.01% S and the balance Fe with inevitable impurities, is melt and cast and further; hot-rolling is performed; at the cooling time, this steel is cooled at 0.5-40C/s average cooling speed at the center part of the steel sheet in the temperature range of 600-450C; and a cold-working or a warm-working is applied at the room temperature to 300C working temperature and 1.5-15 working ratio. Further, the method for producing the high strength steel sheet having 760 MPa class tensile strength and excellent strain-aging characteristic is produced into the steel tube by using the above steel sheet.;COPYRIGHT: (C)2007,JPO&INPIT