| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel material in which toughness in HAZ (weld heat-affected zone) is improved and variations in the HAZ toughness are reduced and also to provide its manufacturing method. SOLUTION: With respect to a steel material which has a composition containing 0.01 to 0.2% C,≤0.5% (not including 0%) Si,≤2.5% (not including 0%) Mn,≤0.03% (not including 0%) Ti and≤0.01% (not including 0%) N, also containing≤0.02% (not including 0%) P,≤0.015% (not including 0%) S and≤0.01% (including 0%) Al, further containing 0.0010 to 0.1% REM and 0.001 to 0.05% Zr and having the balance iron with inevitable impurities, the above REM and Zr are regulated in such a way that they are contained in inclusions and solid-solution REM and solid-solution Zr become≤0.0010% (including 0%) and≤0.0010% (including 0%), respectively. COPYRIGHT: (C)2009,JPO&INPIT
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