The aim of the present invention is to provide a phosphate treated zinc
coated steel sheet with excellent workability. A steel sheet coated with a
zinc based alloy has a phosphate treated coating on the surface thereof.
The phosphate treated coating comprises mainly granulated crystals,
specifically, crystals in which the average ratio of the major axis to the
minor axis is not less than 1.00 and not more than 2.90. Moreover, the
method for producing the phosphate treated coating uses a phosphate
treatment solution in which the amount of Mg ions is .gtoreq.6 g/l and the
amount of Zn ions is .gtoreq.0.5 g/l, or a phosphate treatment solution in
which the amount of Mg ions is .gtoreq.10 g/l, the amount of Zn ions is
0.ltoreq. and <0.5 g/l, and the amount of nitric acid ions is
.gtoreq.40 g/l. Moreover, the phosphate treated zinc coated steel sheet
also has excellent corrosion resistance as the amount of Mg in the
phosphate treated coating is not less than 10 mg/m.sup.2, and has
excellent weldability as the coating amount is controlled to 0.5 to 3.0
g/m.sup.2.
O alvo da invenção atual é fornecer uma folha de aço revestida zinco tratada phosphate com o workability excelente. Uma folha de aço revestida com uma liga baseada zinco tem um revestimento tratado phosphate na superfície disso. O revestimento tratado phosphate compreende principalmente cristais granulated, especificamente, os cristais em que a relação média da linha central principal à linha central menor não é menos de 1.00 e não mais de 2.90. Além disso, o método para produzir o revestimento tratado phosphate usa uma solução do tratamento do phosphate em que a quantidade de íons do magnésio é o gtoreq.6 g/l e a quantidade de íons do zn é o gtoreq.0.5 g/l, ou uma solução do tratamento do phosphate em que a quantidade de íons do magnésio é o gtoreq.10 g/l, a quantidade de íons do zn é 0.ltoreq. e
