Abstract: A colored zinc composite-plated steel sheet which comprises a steel sheet or a plated steel sheet, a colored composite-plating film comprising zinc and an oxide of a coloring metal such as nickel, cobalt, iron, chromium, tin or copper and provided on the steel sheet at a coverage of 0.1-5 g/m.sup.2 and a transparent guard coat of 3 .mu.m or less thick provided on the film is obtained by carrying out electrolysis in an acidic aqueous solution containing zinc ion, a coloring metal ion and nitrate ion, nitrite ion, perchlorate ion, chlorate ion, condensed phosphate ion and having a pH of 1-4 using the steel sheet or plated steel sheet as a cathode at a current density of 5-100 A/dm.sup.2 and a current quantity of 20-200 coulomb/dm.sup.2.

Abstract: A colored zinc composite-plated steel sheet which comprises a steel sheet or a plated steel sheet, a colored composite-plating film comprising zinc and an oxide of a coloring metal such as nickel, cobalt, iron, chromium, tin or copper and provided on the steel sheet at a coverage of 0.1-5 g/m.sup.2 and a transparent guard coat of 3 .mu.m or less thick provided on the film is obtained by carrying out electrolysis in an acidic aqueous solution containing zinc ion, a coloring metal ion and nitrate ion, nitrite ion, perchlorate ion, chlorate ion, condensed phosphate ion and having a pH of 1-4 using the steel sheet or plated steel sheet as a cathode at a current density of 5-100 A/dm.sup.2 and a current quantity of 20-200 coulomb/dm.sup.2.

Abstract: A Zn-Al hot dip galvanized steel sheet having an improved resistance to secular peeling of a galvanized layer, characterized by a composition of the layer and galvanizing bath which consist of from more than 0.3 wt % to 10 wt % of Al, from 0.2 to 1.0 wt % of Sb, a total of less than 0.02 wt % of impurities including Pb and Sn, and a balance of Zn.

Abstract: A hot dip galvanized steel strip in which the zinc based alloy coating exhibits a satisfactory appearance and is firmly fixed to the strip substrate, which strip is produced by a process which comprises coating at least one surface of a steel strip with a melted zinc based alloy controlling the weight of the melted zinc based alloy coating and; solidifying the melted zinc based alloy coating and which process is characterized in that the zinc based alloy contains 0.1 to 2.0% by weight of magnesium and in at least a portion of a stage in which the melted zinc based alloy coating is still in the fluid state, the zinc based alloy coating is exposed to an oxygen-controlled atmosphere containing 1000 ppm or less of molecular oxygen, the controlling procedure for the weight of the melted zinc based alloy coating being carried out in the oxygen-controlled atmosphere.

Abstract: Electroplating in an acidic zinc-nickel alloy plating bath containing vanadium ions as a third component provides a plating having a surprisingly high level of corrosion resistance equal to about 10 times that of pure zinc.

Abstract: An aqueous solution for treatment of metal surfaces which has a pH value greater than 7, and comprises no free inorganic acid and 0.1 to 10% by weight, estimated as Cr, of a chromium compound in which 5 to 40% of the initial quantity of Cr(VI) is reduced by a reaction with a trifunctional phenol.