| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength hot rolled steel sheet excellent in workability and fatigue characteristics and having superior surface characteristics at a relatively low cost. <P>SOLUTION: The high-strength hot rolled steel sheet with excellent workability, fatigue characteristics, and surface characteristics has a composition containing, by mass, 0.03 to 0.15% C, 0.5 to 2% Mn, 0.01 to 0.1% Al and <=0.02% (including 0%) S, also containing >0.030 to 0.08% P, 0.3 to 1.00% Cr and <=0.1% (including 0%) Si and having the balance Fe with inevitable impurities and also has a metallic structure containing polygonal ferrite as a primary phase and martensite as a secondary phase. <P>COPYRIGHT: (C)2005,JPO&NCIPI.
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