| 摘要 |
PROBLEM TO BE SOLVED: To produce a laminated steel sheet for a welded can excellent in laminating adhesion, high speed weldability and corrosion resistance and producible at a relatively low cost. SOLUTION: The surface of a steel sheet 1 is applied with a tin layer formed without executing tin melting treatment, a chemical convertion treated layer with prescribed coating weight and a laminate film layer in order from the lower layer side. The tin layer is composed of the one in which granular tin layer parts 2 and 3 in which the lower layer side is composed of tin-iron alloy and the upper layer side is composed of metallic thin and the balance flattin- iron alloy layer part 4 coexist. As the granular tin layer parts, in each tin layer part occupying >=90% of the granular tin layer part, the thickness (a) of the maximum thickness part is regulated to <=0.8μm, and the thickness (a)1 of the maximum thickness part in the metallic tin on the upper layer side is regulated to 0.1 to 0.7μm in the steel sheet 1 having 0.19mm sheet thickness and to 0.2 to 0.7μm in the steel sheet 1 having <0.19mm sheet thickness, respectively. Furthermore, the area of the grains is regulated to 0.2 to 0.3μm<2> , and the steel sheet surface coating area ratio of the granular tin layer parts satisfying the above conditions is regulated to >=10%, and, in the flat tin-iron alloy layer part, the thickness (b) is regulated to 0.01 to 0.05μm, and the steel sheet surface coating area ratio is regulated to >=60%. |
