High-strength steel sheet having excellent processability and method for manufacturing same

Example

[0128]After preparing a steel slab having the alloy composition illustrated in Table 1 below, the steel slab was heated to a temperature in a range of 1050 to 1250° C., and then hot rolled, cooled, and coiled under the conditions illustrated in Table 2 to prepare a hot rolled steel sheet.

[0129]Thereafter, each hot rolled steel sheet was pickled, and then cold rolled at a cold rolling reduction ratio of 40 to 70% to prepare a cold rolled steel sheet, and then subjected to continuous annealing under the conditions illustrated in Table 2 below, followed by stepwise cooling (2nd and 3rd), and then, was maintained in the range of 70 to 100 seconds at the third cooling end temperature. In this case, the third cooling was performed in a hydrogen cooling facility.

[0130]Thereafter, zinc plating was performed in a hot-dip galvanizing bath (0.1 to 0.3% Al-residual Zn) at 430 to 490° C., followed by final cooling and followed by temper rolling to 0.2%, to prepare a hot-dip galvanized steel