STEEL SHEET COATED WITH SN-BASE MULTILAYERED FILM AND HAVING SUPERIOR CORROSION RESISTANCE, WELDABILITY AND PAINTABILITY AND ITS MANUFACTURE

摘要

PURPOSE:To manufacture a steel sheet coated with an Sn-base multilayered film and having superior corrosion resistance, weldability and paintability by successively forming an Fe-Ni-P undercoat layer, an Sn layer by tinning and a chromate layer on the surface of a steel sheet under specified conditions. CONSTITUTION:An Fe-Ni-P undercoat layer contg. 5-30wt%, preferably 10-25wt% Ni and 0.1-10wt%, preferably 1-5wt% P is formed on the surface of a steel sheet by 30-300mg/m2, preferably 100-250mg/m2 per one side. An Sn layer is formed on the undercoat layer by tinning by 300-2,500mg/m2, preferably 550-1,500mg/m2 per one side. A chromate layer is then formed on the Sn layer by 5-50mg/m2, preferably 7.5-35mg/m2 (expressed in terms of metallic Cr). Thus, a steel sheet coated with an Sn-base multilayered film and showing superior performance as the material of a vessel is manufacture at a low cost.