| 摘要 |
PROBLEM TO BE SOLVED: To suppress low the amounts of expensive alloy elements to be added to a steel and to obtain high cold and high temp. strength. SOLUTION: This building steel has a compsn. contg. 0.04 to 0.15% C, <=0.5% Si, 0.5 to 2.0% Mn, 0.1 to 1.0% Mo, <=0.010% Al and <=0.012% N, furthermore contg. one or more kinds among 0.01 to 0.10% V, 0.01 to 0.04% Nb and 0.1 to 0.5% Cr, and the balance Fe with inevitable impurities, and in which the content of active N obtd. by the formula is regulated to >=0.002%. In this case, higher cold and high temp. strength can be obtd. compared to those of a steel sheet added with the same amounts of alloy elements: the formula: active N(%)=N(%)- 1/2×Al(%)}.
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