JPH05311374

PURPOSE:To realize a plated steel sheet excellent in plating adhesion by allowing an alloy layer constituted of Mg, Si and Al to exist on the boundary between an alloy layer of plating components and iron and a high Si high tensile strength steel sheet. CONSTITUTION:A hard-to-plate high tensile strength steel sheet 1 contg. >=0.3% Si in steel is passed through at 40 to 180m/min line speed. After the change in the direction by a turn down roll 2, it is introduced into a hot dip plating pot 3. A galvanizing bath 8 has a compsn. constituted of 0.05 to 0.3% Al and 0.02 to 0.3% Mg, and the balance Zn with inevitable impurities. By incorporating Mg into the bath, it is brought into reaction with Si formed by a reducing reaction to form an intermetallic compound of Mg2Si. Furthermore, Mg effectively reduces Si oxide, and it melts in a galvanizing bath contg. Al into a liquid shape in an ordinary operating range, therefore, it is a very effective element for improving its plating properties.