| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a steel sheet for an extra-thin vessel remarkably good in flange formability while the productivity at the time of annealing is improved by a high 2CR ratio and the freeing of an annealing schedule. SOLUTION: This is a method for producing a high strength and high ductility steel sheet or a vessel having a sheet thickness of <=0.400 mm in which steel containing, by weight, <=0.0600% C and <=0.0100% N, and the balance Fe with inevitable impurities is cold-rolled, is thereafter subjected to recrystallization annealing in a continuous annealing furnace, is subjected to nitriding treatment and carburizing treatment or carbonitriding treatment in such a manner that the amount of the total of N and C to be increased reaches 20 to 300 ppm to control the content of C to <=0.065%, and N to <=0.0300% and is subsequently subjected to re-cold rolling of 10 to 50%.
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