| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet having excellent weldability in addition to its characteristics of high strength and high ductility. SOLUTION: In the high strength and high ductility steel sheet having excellent weldability, within crystal grains, retained austenite with the average grain diameter of≤500 nm is contained in 3 to 20% by a space factor as a second phase structure, and also, the concentration of C is≤0.1 mass%. The second phase structure contains an austenite stabilization element(s), and the content of the austenite stabilization element(s) in the second phase structure is higher than the content of an austenite stabilization element(s) by≥10 mass%. COPYRIGHT: (C)2007,JPO&INPIT
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