METHOD FOR PRODUCING HOT-ROLLED STEEL SHEET FOR LOW YIELD-RATIO ELECTRIC-RESISTANCE WELDED STEEL TUBE EXCELLENT IN LOW TEMPERATURE TOUGHNESS

摘要

PROBLEM TO BE SOLVED: To obtain a hot-rolled steel sheet for low yield-ratio electric-resistance welded steel tube excellent in low temperature toughness.;SOLUTION: A slab composed of 0.01-0.09%C, ≤0.50%Si, ≤2.0%Mn, 0.01-0.10%Al, 0.01-0.10%Nb and further, one or more among ≤0.5%Cu, ≤0.5%Ni, ≤0.5%Cr, ≤0.5%Mo so as to satisfy Pcm(%)≤0.16% and the balance Fe with inevitable impurities is finished to the hot-rolling at not lower than the temperature satisfying X(°C)=-700×C%+900, and after cooling to ≤650°C at ≥5°C/s cooling speed, the steel sheet is coiled.;COPYRIGHT: (C)2007,JPO&INPIT