Abstract: A surface treated steel materials coated with manganese having a film of MmOOH (manganic hydroxide) formed thereon, which show excellent corrosion resistance, workability and weldability. The surface treated steel materials may be further coated with zinc as a base coating underlying the manganese coating or further coated with a coating of at least one selected from the group consisting of P, B, Si, Cu, Mn, Cr, Ni, Co, Fe, Zn, Al, Ca, Mg, Ti, Pb, Sn, inorganic carbon and their compounds and still further coated with an organic coating. The film of MmOOH (manganic hydroxide) is formed by a treatment in an aqueous solution containing Cr.sup.6+.

Abstract: Manganese coated steel materials having a compact film of hydrated manganese oxide formed on the manganese coating by heating and drying. Manganese coated steel materials of the present invention show very excellent corrosion resistance in ordinary corrosive environments as well as special corrosive environments such as marine environments and young plant cultivation in mountaineous forests. For further improvement of corrosion resistance, organic coating and metal coatings are applied.

Abstract: A steel sheet having a two-layer film which exhibits excellent lubricating properties under press working can be manufactured by one step coating. In this case the coating composition after being applied to the sheet is irradiated with ionizing radiant energy, i.e., radioactive ray or electromagnetic wave, in an atmosphere containing an oxidizing substance.The outermost layer obtained is an uncured or unhardened semi-fluid layer but the layer contacting the surface of the steel sheet is a cured or hardened resin layer. If a lubricant is incorporated in the coating composition, or if the main component of the coating composition has one double bond per molecule, the result is more advantageous.

Abstract: A steel pipe is coated with resin at high temperature. After the temperature is lowered slightly below the softening point of the resin, the coated pipe is cut to length and then allowed to be cooled down to an ordinary temperature, meanwhile the resin is freely shrunk, leaving little residual strain in the cooled product coating.A cooling means for cooling the coating from the middle toward the ends in its longitudinal direction and a means for cooling the coating forcibly are provided.

Abstract: A method for electroplating a metal strip to be plated includes continuously running the metal strip through the interior of a plating vessel of a cylindrical form having a rectangular cross section, the upper and lower walls of such vessel being constructed of an insoluble anode material which is to function as an anode, and compulsively circulating a plating solution in a direction counter to the running direction of the metal strip within the plating vessel and an apparatus for carrying out the same, whereby a high speed plating is performed and the replacement of the anodes can be minimized.

Abstract: A hot-rolled coil having excellent adaptability for pickling can be produced by applying to the sides of the hot-rolled coil, a compound of an alkaline metal or alkaline earth metal, or an oxygen compound of boron, germanium, tin, antimony, lead, bismuth or vanadium. One or more of the aforesaid compositions when applied to a hot-rolled coil serves to suppress the formation of oxide film on the surface of the coil and/or promotes the solubility of the oxide film in the pickling tanks to the extent such oxide film does form.