| 摘要 |
PROBLEM TO BE SOLVED: To provide a high strength cold-rolled sheet with excellent moldability, which has a tensile strength of TS:980 MPa or more.SOLUTION: In the high strength cold-rolled sheet with excellent moldability, an original sheet for annealing is a thin steel sheet made by forming a sedimentary layer of proper thickness by a cold spray method which sprays iron-based particles of proper particle diameters mixed with actuation gas of 500 to 1000°C, on a surface of substrate. The thin steel sheet has a composition satisfying that the substrate is C:0.10% or more in mass%, and Mneq is 2.5 or more, and the sedimentary layer is C:less than 0.20% in mass% and Mneq is less than 2.5. Cold rolling of rolling reduction:20 to 90%, and annealing processing at 700 to 900°C are applied on the original sheet for annealing. When the substrate is cold-rolled sheet, only annealing is performed, and thereby, the substrate has a hardness of 300HV or more in Vickers hardness, and the soft layer has a layer with hardness less than 300HV in Vickers hardness, and such a soft layer of proper thickness is provided. |
