| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin steel sheet having a press-formability applicable to inner and outer plates for automobile, having the tensile strength of 340 MPa to <590 MPa and excellent in secondary working brittleness resistance and a manufacturing method therefor. SOLUTION: This steel sheet is composed by mass% of≤0.05% C,≤2.0% Si,≤3.0% Mn,≤0.1% P,≤0.03% S,≤0.1% Al,≤0.01% N and the balance substantially of Fe, and the micro structure is composed of ferrite and a low temperature transformed phase of <10% volume fraction and an inequality d<-0.5×Vm+16(Vm<10%) is satisfied; where d(μm) denotes the grain size of ferrite and Vm(%) is the low temperature transformation phase fraction. COPYRIGHT: (C)2009,JPO&INPIT
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