Abstract: Electrolytic galvanizing process in which steel strip to be zinc coated is passed continuously through an acid electrolyte solution containing zinc ions and is used as a cathode, while the electrolyte solution is made to flow in the space between the cathode and the anode, in a cell having flat parallel electrodes. The plating current density and the fluid dynamic conditions of the electrolyte are related by the equationI=K C Re.sup.nin which I is 15-300 A/dm.sup.2, K is 0.01-0.0001 A/dm.sup.2 l/g, C is 40-80 grams of zinc per liter of electrolyte solution, Re is the Reynolds number between 1,000 and 200,000, and n is 0.55-0.85. Preferred values are K=0.001, C=80 g/l and n is 0.7.

Abstract: This invention relates to the continuous annealing of moving steel strips. A rapid quenching between the annealing treatment and the overaging process is effected in an electrolytic pickling bath, in which the steel strip acts first as a cathode and thereafter as an anode. The current density applied to the steel strip acting as a cathode in the electrolytic pickling bath is regulated so as to control the amount of hydrogen developed on the strip surface and, concurrently, to control the quenching speed of said steel strip.

Abstract: Improved process for the production of coated steel sheet particularly suitable for the fabrication of car bodies, galvanized and further protected by a layer of metallic chromium and hydrated oxides of chromium. The improvement consists in optimizing process operating conditions, within certain limits, to obtain a protective layer of chromium and hydrated oxides of chromium with absolutely new morphological characteristics which endow the product with corrosion resistance far greater than that of similar products reported in the literature.

Abstract: Steel sheet, especially suitable for car-body fabrication, galvanized and further protected by a layer of metallic chromium and hydrated oxides of chromium, electrolytically deposited. The improvement is that the metallic chromium is present in extremely fine particles that exert a very marked covering and protective effect on the underlying zinc. In this way, and with the help of the chromium oxides that further cover and protect the underlying layers, a product is obtained whose corrosion resistance is far superior to that of similar products.

Abstract: Thin metal plate is cleaned and electrolytically pickled in an acid solution. A zinc layer is electrodeposited on one face of the plate, after which a chrome-chromic oxide coating is deposited on both faces of the plate from a sulphuric acid solution containing compounds of trivalent and exhavalent chrome. The plate is then subjected to a drying-oxidating treatment in air. The plate may be steel having a thickness between 0.1 and 2 mm. The plate may be surface treated by phosphating, and then painted. The chrome-chromic oxide coating may have a thickness between 0.05 and 5 .mu.m, and the zinc coating a thickness between 1 and 30 .mu.m.

Abstract: Thin metal plate is cleaned and electrolytically pickled in an acid solution. A zinc layer is electrodeposited on one face of the plate, after which a chrome-chromic oxide coating is deposited on both faces of the plate from a sulphuric acid solution containing compounds of trivalent and hexavalent chrome. The plate is then subjected to a drying-oxidating treatment in air. The plate may be steel having a thickness between 0.1 and 2 mm. The plate may be surface treated by phosphating, and then painted. The chrome-chromic oxide coating may have a thickness between 0.05 and 5 .mu.m, and the zinc coating a thickness between 1 and 30 .mu.m.

Abstract: The adhesion of paint to steel sheets is improved by pretreating the steel sheets, prior to conventional annealing, surface finishing, oiling, degreasing, phosphating and painting operations, by connecting the steel sheet alternately as cathode and anode in an electrolytic cell containing a bath of 0.5 M-2 M sodium sulphate aqueous solution. The operating temperature is 20.degree.-100.degree. C., the pH is 6-8, the current density is 1 to 50 A/dm.sup.2, and the treatment time is 0.1-30 seconds, preferably 0.5-20 seconds, and most preferably about 5 seconds as cathode followed by about 5 seconds as anode.

Abstract: The electrolytic pickling of silicon electrical steel sheet that follows hot rolling, is improved by limiting the potential imposed on the steel, during the anodic phase thereof, to less than +1 V with respect to the standard hydrogen electrode, preferably less than +0.8 V. The avoidance of electrolysis of the aqueous medium shortens the treatment time, reduces energy consumption, avoids over-pickling, facilitates subsequent rolling, reduces the subsequent rolling load, improves adherence of the subsequently applied glass film, and renders more uniform the magnetic characteristics of the steel.

Abstract: A weathering steel has high toughness and rapidly develops a protective oxide coating and contains C 0.05 - 0.15, Mn 0.5 - 1.5, Cu 0.2 - 0.5,Al 0.2 - 0.5, Si 0.1 - 0.8, Cr 0.5 - 1.5, S up to 0.02, P up to 0.04, Nb up to 0.020, N up to 0.010 Mo up to 0.15, Ti up to 0.1, balance essentially iron, the proportions being as follows:2.6(Mn%) + 3.2(Cu%) + 41.6(Nb%) + 1.3(Cr%/Al%) = 7.4 to 10.1 the value of Cr%/Al% being from 2 to 5, preferably from 3 to 4.

Abstract: The present invention relates to a zinc-based alloy for coating steel and products coated therewith. More exactly, the invention relates to a low-alloy zinc suitable for the continuous coating of steel, particularly in the form of sheet and wire, on Sendzimir coating lines and to the products coated with said alloy.