| 摘要 |
A cold-rolled steel sheet, which is free from wrinkle formation caused by slow-aging and ensures a baking curing amount of at least 50 MPa after a relatively low strain-imparting treatment of less than 2.0%, i.e., a heat treatment corresponding to paint-baking, obtained by: heating, to 1150°C or higher, a steel material which comprises, in terms of mass%, 0.020-0.070% of C, 0.05% or less of Si, 0.1-0.5% of Mn, 0.05% or less of P, 0.02% or less of S, 0.02-0.08% of Al and 0.005-0.02% of N; finish-rolling at a finish-rolling termination temperature of 850°C or higher to give a hot-rolled sheet; winding at such a winding temperature as satisfying a specific relational expression to Al and N contents; conducting cold-rolling at a rolling reduction of 60-90%; heating and soaking, while controlling the heating speed in two stages, to such an annealing temperature as satisfying a specific relational expression to Al and N contents and winding temperature; and then cooling to 500°C or lower at a cooling speed of 5°C/s or higher. |
