| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high-strength hot-dip galvanized steel sheet that requires no addition of large amounts of expensive elements such as Mo and Cr and no special CGL heat history, and has low YP, high BH, excellent aging resistance and excellent corrosion resistance, and to provide a method for producing the same. <P>SOLUTION: The steel includes, by mass, C: >0.015% and <0.100%, Si: ≤0.3%, Mn: <1.90%, P: ≥0.15 and ≤0.05%, S: ≤0.03%, sol. Al: ≥0.01 and ≤0.5%, N: ≤0.005%, Cr: <0.30%, B: ≥0.0003 and ≤0.005%, and Ti: <0.014%, wherein 2.2≤[Mneq]≤3.1 and 0.42≤8[%P]+150B<SP>*</SP>≤0.73 are satisfied. The steel structure has ferrite and a second phase. The surface area ratio of the second phase is 3-15%, the ratio of martensite and residual γ surface area ratio to the second phase surface area ratio is more than 70%, and the ratio of the surface area ratio present at the grain boundary triple points, of the second phase surface area ratio, is 50% or more. <P>COPYRIGHT: (C)2010,JPO&INPIT |
