Make manner null of the steel for full house thermal welding and the steel for full house thermal

摘要

PROBLEM TO BE SOLVED: To produce a steel sheet which has excellent toughness in a heat affected zone even on high heat input welding, and to provide a method for preparing molten steel used for the stock therefor. ;SOLUTION: The steel has composition containing, by mass, 0.01 to 0.15% C, 0.05 to 0.80% Si, 0.5 to 2.0% Mn, 0.01 to 0.06% Al, 0.003 to 0.013% rare earth elements and ≤0.005% S, and the balance iron with inevitable impurities. Grains consisting of the oxides and/or sulfides of rare earth elements are dispersed therein in ≥10⁷ pieces/cm², and the grain size thereof is controlled to ≤500 nm.;COPYRIGHT: (C)2003,JPO