| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a hot dip galvannealed steel sheet for press working which is excellent in surface appearance less in the variation of plating thickness and exhibiting a fine surface appearance even after press working.SOLUTION: The method includes: a stage of obtaining a slab having a componential composition containing 0.0005 to 0.01% C, ≤1.0% Si, 0.01 to 1.5% Mn, 0.005 to 0.08% P, ≤0.02% S, 0.01 to 0.10% Al, ≤0.1% Ni and ≤0.1% Cu, and the balance Fe with inevitable impurities; a stage of performing hot rolling so as to obtain a hot rolled coil; a stage of feeding microbubbles having the average bubble diameter of 0.01 to 100 μm and further pickling the surface of the steel sheet in a state where ultrasonic waves of 10 kHz to 3 MHz are applied thereto; a stage of subjecting the steel sheet to cold rolling at a cold rolling ratio of 50 to 95% so as to be a cold rolled coil with a prescribed thickness; and a stage of annealing the coil at a temperature above a recrystallization temperature and thereafter applying hot dip plating to the surface of the coil. |
