| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high strength-high ductility wire rod having a tensile strength of≥700 MPa and a reduction of an area of≥73% by a method applicable to actual commercial production without so changing the conventional production process using a common low carbon steel having sufficient recycling properties. <P>SOLUTION: A steel comprising fine martensite of≥80% obtained by subjecting a common low carbon steel to thermomechanical treatment to thereby refine the average austenite grain size to≤50μm, and thereafter performing water cooling, is subjected to cold wire drawing under the condition satisfying the total reduction of area of 20 to <60%, and is annealed, so that a hyperfine grain ferrite structure having the average crystal grain size of≤1μm is obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
