| 摘要 |
Provided is a cold-rolled steel sheet with superior shape fixability and a manufacturing method therefor. On a steel raw material having a composition comprising, in mass%, C: 0.0010-0.0030%, Si: 0.05% or less, Mn: 0.1-0.5%, Ti: 0.021-0.060%, B: 0.0005-0.0050%, and containing B and C so that B/C is 0.5 or more, are performed: a hot-rolling process for finish-rolling with a finish-rolling completion temperature of 870-950°C and winding at a winding temperature of 450-630°C; a cold-rolling process with a cold-rolling reduction of 90% or less; and, after the cold-rolling process, an annealing process for heating to a soaking temperature in the range of 700-850°C at an average heating rate of 1-30°C/sec in the temperature range of 600°C and above, and, after holding for 30-200 sec, cooling to the temperature range of 600°C with a cooling rate averaging 3°C/sec or more. Obtained thereby is a cold-rolled steel sheet with superior shape fixability, the sheet having a structure wherein the main constituent is ferrite with a mean particle diameter of 10-30 µm and the proportional limit is 100 MPa or less. |
