HOT-DIP Sn-Zn SYSTEM COATED STEEL SHEET HAVING GOOD CORROSION RESISTANCE

摘要

A hot-dip Sn-Zn system coated steel sheet comprising a steel sheet and a hot-dip coating layer which is formed on the surface of the steel sheet and comprises 1 to 8.8% by mass of Zn and a remainder composed of 91.2 to 99.0% by mass of Sn and impurities, the ratio of the endothermic value produced by the Sn-Zn eutectic crystal melting and the endothermic value produced by the Sn primary crystal melting in the hot-dip coating layer satisfying the following formula: (endothermic value produced by Sn primary crystal melting)/[(endothermic value produced by Sn primary crystal melting)+(endothermic value produced by Sn-Zn eutectic crystal melting)] = 0.3; and the temperature of endothermic peak produced by the Sn primary crystal melting being not lower than 200°C and not higher than 230°C or lower and that produced by the Sn-Zn eutectic crystal melting being not lower than 198°C and lower than 200°C.