| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet for hot pressing satisfying the strength of a component after hot pressing and quenching, the cutting properties and blanking properties of the component, and delayed fracture properties and spot weldability as well. SOLUTION: The high strength steel sheet for hot pressing has a composition containing, by mass, 0.15 to 0.3% C, 0.005 to 1.0% Si, 0.01 to 3.0% Mn, 0.005 to 0.1% P,≤0.02% S, 0.01 to 3.0% Al,≤0.01% N, 0.02 to 0.5% Cr, 0.002 to 0.5% V, 0.0002 to 0.01% B and 0.0002 to 0.01% Mg, and the balance iron with inevitable impurities. The steel comprises multiple oxide of one or more kinds selected from the oxide, sulfide, multiple crystallized products and multiple precipitated products of Mg with a mean grain size in the range of 0.01 to 5.0μm by 1×10<SP>2</SP>to 10<SP>7</SP>pieces per square mm, and also, the inequality (A); 0.35≥C+Si/30+Mn/20+Cr/20+Mo/15+V/10+4×B+2×P+4×S is satisfied. COPYRIGHT: (C)2006,JPO&NCIPI
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