HEISSTAUCH Zn-Al-Mg BESCHICHTETES STAHLBLECH MIT HERVORRAGENDEN KORROSIONSEIGENSCHAFTEN UND OBERFLÄCHENAUSSEHEN UND VERFAHREN ZUR HERSTELLUNG

摘要

A hot-dip Zn-Al-Mg plated steel sheet good in corrosion resistance and surface appearance that is a hot-dip Zn-base plated steel sheet obtained by forming on a surface of a steel sheet a hot-dip Zn-Al-Mg plating layer composed of Al: 4.0-10wt.%, Mg: 1.0-4.0wt.% and the balance of Zn and unavoidable impurities, the plating layer having a metallic structure including a Äprimary crystal Al phaseÜ or a Äprimary crystal Al phaseÜ and a ÄZn single phaseÜ in a matrix of ÄAl/Zn/Zn2Mg ternary eutectic structureÜ. To obtain a plating layer possessing this metallic structure, the cooling rate of the plating layer adhering to a steel strip extracted from a plating bath and the plating bath temperature are appropriately controlled in a continuous hot-dip plating machine and/or appropriate amounts of Ti and B are added to the bath. Occurrence of a stripe pattern peculiar to this plated steel sheet is controlled by morphology control of a Mg-containing oxide film up to solidification of the plating layer or by adding an appropriate amount of Be to the plating bath.