| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high-strength cold-rolled steel sheet which achieves the improvement in TS-EL balance and the reduction in a springback value in a high strength region of about 550 to 900 MPa class and has excellent workability and shape freezing property. <P>SOLUTION: The high-strength cold-rolled steel sheet excellent in workability and shape freezing property: satisfies a prescribed component composition; has a structure comprising a mother phase structure of ferrite and a second phase structure of retained austenite and martensite (the martensite may not be included); and satisfies the following expressions (1) and (2), when the volume fraction of the ferrite in the whole structure is represented by Vf(%), the volume fraction of the retained austenite in the whole structure is represented by Vγ(%), the carbon content in the retained austenite is represented by Cγ(mass%), the shortest distance between the second phase structures is represented by dis(μm), and the average grain size of the second phase structures is represented by dia(μm), (Vf×Vγ×Cγ×dis)/dia≥300 ...(1), and dis≥1.0μm ...(2). <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
