STEEL PLATES USED FOR CONTAINERS AND METHODS OF MANUFACTURING THEM

Abstract

The invention relates to a steel plate (1) for use as a lead-free container with superior weldability and superior surface appearance. The steel plate (1) for use as a container consists of, on the surface of the steel plate (2), a chromium metal layer (3) and a hydrated chromium oxide layer (4) stacked in this order from the side closer to the steel plate (2). The weight of the chromium metal layer (3) is from 50 to 200 mg / m2, and the weight of the hydrated chromium oxide layer (4) in chromium is from 3 to 50 mg / m2. The chromium metal layer (3) consists of a flat plate (3a) and protrusions (3b) arranged on the flat plate (3a). The height (H) of each protrusion (3b) is 10 runs or greater and protrudes more than 500 nm, the base diameter (D) of each protrusion (3b) is 50 nm or greater and 1000 nm or less, the ratio (H / D) of height (H) and base diameter (D) is less than 0.50, and the area of ​​the protrusions (3b) is 5% or greater.