| 摘要 |
PURPOSE:To provide the titled zinc alloy forming a plating film which exhibits substantial corrosion resistance even under severe conditions and has high hardness to withstand the contact and impact during handling by incorporating a specific ratio of Mg therein an controlling the contents of inevitable impurities such as Pb, Cd, Fe or Sn etc., and comprising the alloy of the balance Zn. CONSTITUTION:The zinc alloy for zinc hot dip coating of this invention contains 0.03-0.8wt% Mg and 0.01wt% in total of inevitable impurities suchas Pb, Cd, Fe or Sn, etc. The Mg component in the zinc hot dip coating bath combines with Zn to solutionize as the intermetallic compd. in the form of MbZn2 or Mg2Zn3. The alloying reaction of Zn-Fe, therefore, progresses preferentially when steel products are immersed in said plating bath. A Zn-Ma alloy layer is formed on the Zn-Fe alloy layer on the steel products pulled up from the bath. The alloy layer is harder than the plating film of the steel plated with Zn alone and decreases the damages on the plating film in the stage of the above-mentioned contact and impact. The plating on the iron and steel products at 440-480 deg.C bath temp. is possible when the Zn alloy of this invention is used.
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