HOT ROLLED STEEL SHEET FOR ELECTROSEAMED STEEL PIPE HAVING BOARD THICKNESS OF 15 MM OR MORE

摘要

PROBLEM TO BE SOLVED: To secure strength and toughness, further low temperature toughness which are needed as a raw material of an electric welded oil well pipe in a hot rolled steel sheet for electroseamed steel pipe having a board thickness of 15 mm or more.;SOLUTION: There is provided a hot rolled steel sheet for electroseamed steel pipe having a board thickness of 15 mm or more having a component composition containing, by mass%, C:0.06 to 0.10%, Si:0.10 to 0.50%, Mn:1.70 to 1.90%, Ti:0.010 to 0.025%, B:0.0010 to 0.0025%, Mo:0.04 to 0.25%, V:0.040 to 0.060%, Nb:0.040 to 0.060% and further P:0.03% or less, S:0.004% or less, O:0.0040% or less and the balance Fe with inevitable impurities, a metal structure of tempered upper bainite and minor axis of old γ particle with an oval shape of 25 μm or less.;COPYRIGHT: (C)2015,JPO&INPIT