Abstract: A Zn-Ni alloy plated steel plate having stable formability may be obtained by subjecting the plated surface of a Zn-Ni alloy plated steel plate having Ni contents of 10 to 17 wt. % to a dipping treatment, a spraying treatment or to an anodic treatment, using a solution containing one or both H.sub.2 PO.sub.4.sup.- and HPO.sub.4.sup.2-.

Abstract: A hot rolled steel sheet having a specific composition and having a specific small grain size of ferrite constituting the steel sheet has high resistances against secondary-work embrittlement and brazing embrittlement and is adapted for ultra-deep drawing. The specific small grain size of the ferrite can be obtained by limiting the hot rolling condition of a slab having the specific composition.

Abstract: A zinc-nickel alloy is electrodeposited on a steel strip by passing the steel strip through a stream of sulfuric acid-containing plating solution which contains 2-3 mol/liter in total of Zn.sup.2+, Ni.sup.2+, H.sup.+, and SO.sub.4.sup.2- ions and at least 0.1 mol/liter of Na.sup.+, K.sup.+, or NH.sub.4.sup.+ ion at pH 1 to 2.5, feeding the solution at a flow speed of at least 1 m/sec., and applying electricity between the strip and an anode in the solution such that the current density between the strip and the anode at the outlet of the solution is lower than that at the inlet of the solution. The anode may preferably be divided into a plurality of segments. This process may be carried out by use of a radial or horizontal cell.

Abstract: A surface-treated steel strip adapted for electric resistance welding is prepared by forming a first layer of iron-nickel alloy on a steel strip, said first layer having a weight ratio of Ni/(Fe+Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tin or iron-tin-nickel alloy on said first layer by tin plating to a coating weight of 0.1 to 1 g/m.sup.2 of tin and optionally, causing the tin to reflow, and forming a third layer on said second layer by effecting an electrolytic chromate treatment, said third layer consisting essentially of metallic chromium and hydrated chromium oxide, wherein the electrolytic chromate treatment is carried out in a bath which contains an amount of a chromate compound to give 10 to 100 g/l of CrO.sub.3 and has a weight ratio of H.sub.2 SO.sub.4 /CrO.sub.3 in the range between 3/1000 and 1/100.

Abstract: A cold rolled steel sheet or plated steel sheet having an improved press formability as well as excellent phosphatability, resistance to galling and spot weldability is produced by controlling a surface roughness pattern of the steel sheet so as to satisfy a center-line average surface roughness of 0.3-2.0 .mu.m and a regularity parameter in at least one direction of not more than 0.25 defining the regularity of surface roughness.

Abstract: Composite plated steel strips comprising a zinc base layer electrodeposited on at least one surface of a steel strip exhibit excellent corrosion resistance with or without painting provided that the zinc base layer contains 0.1 to 10% by weight of cobalt, 0.05 to 5% by weight of chromium, 0.05 to 8% by weight of aluminum, and optionally, 0.05 to 5% by weight of Si, the balance being zinc. Such composite plated steel strips are prepared by subjecting a steel strip to composite electroplating in an acidic zinc plating bath which contains at least one water-soluble compound of Co.sup.2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr.sup.3+ in an amount of 0.2 to 2.5 g/l of metallic chromium, a pseudo-boehmite like alumina sol in an amount of 0.5 to 20 g/l of alumina, and optionally, colloidal silica in an amount of 0.5 to 20 g/l of silica at pH 1 or higher and a current density of at least 40 A/dm.sup.2.

Abstract: A tin-free steel strip comprising a steel strip, 40 to 150 mg/m.sup.2 of a metallic chromium layer on the steel surface, and 5 to 25 mg/m.sup.2 of a chromium compound containing layer thereon wherein the metallic chromium layer contains a plurality of protrusions, exhibits improved corrosion resistance and weldability and is thus useful in the manufacture of welded cans. Preferably, 1.times.10.sup.11 to 1.times.10.sup.14 protrusions having a diameter of 5 to 1000 nm at the base thereof are present per square meter of the metallic chromium layer surface. The tin-free steel strip is produced by chromium plating a steel strip in an aqueous solution containing CR.sup.6+ preferably to a weight of 40 to 140 mg/m.sup.2, subjecting the chromium plated strip to anodic electrolysis, preferably at an eectricity quantity of 0.1 to 10 C/dm.sup.2, and subjecting the strip to a cathodic treatment in an aqueous solution containing Cr.sup.

Abstract: Composite plated steel strips comprising a zinc base layer electrodeposited on at least one surface of a steel strip exhibit excellent corrosion resistance with or without painting provided that the zinc base layer contains 0.1 to 10% by weight of cobalt, 0.05 to 5% by weight of chromium, 0.05 to 8% by weight of aluminum, and optionally, 0.05 to 5% by weight of Si, the balance being zinc. Such composite plated steel strips are prepared by subjecting a steel strip to composite electroplating in an acidic zinc plating bath which contains at least one water-soluble compound of Co.sup.2+ in an amount of 0.3 to 60 g/l of metallic cobalt, at least one water-soluble compound of Cr.sup.3+ in an amount of 0.2 to 2.5 g/l of metallic chromium, a pseudo-boehmite like alumina sol in an amount of 0.5 to 20 g/l of alumina, and optionally, colloidal silica in an amount of 0.5 to 20 g/l of silica of pH 1 or higher and a current density of at least 40 A/dm.sup.2.

Abstract: Surface-treated steel strips suitable for electric resistance welding are prepared by forming a first layer of iron-nickel alloy on a steel strip, said first layer having a weight ratio of Ni/(Fe+Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tin or iron-tin-nickel alloy on said first layer by tin plating to a coating weight of 0.1 to 1 g/m.sup.2 of tin and optionally, causing the tin to reflow, and forming a third layer on said second layer by effecting an electrolytic chromate treatment, said third layer consisting essentially of metallic chromium and hydrated chromium oxide in a total amount of 5 to 20 mg/m.sup.2 calculated as elemental chromium. More preferably, the electrolytic chromate treatment is controlled such that at least 2 mg/m.sup.2 of metallic chromium is present in the third layer.

Abstract: A surface-treated steel strip comprising a steel substrate, islands of metallic tin distributed on one major surface of the steel substrate, and a chromate coating deposited on the substrate major surface to cover the tin islands can be coated with lacquer, baked and then seam welded into food cans.

Abstract: Surface-treated steel strips suitable for electric resistance welding are prepared by forming a first layer of iron-nickel alloy on a steel strip, this first layer having a weight ratio of Ni/(Fe+Ni) in the range between 0.02 and 0.50 and a thickness of 10 to 5,000 angstroms, forming a second layer of tin or iron-tin-nickel alloy on the first layer by tin plating to a coating weight of 0.1 to 1 g/m.sup.2 of tin and optionally, causing the tin to reflow. A third layer is formed on the second layer by effecting an electrolytic chromate treatment, this third layer consisting essentially of metallic chromium and hydrated chromium oxide in a total amount of 5 to 20 mg/m.sup.2 calculated as elemental chromium. Preferably, the electrolytic chromate treatment is controlled so that at least 2 mg/m.sup.2 of metallic chromium is present in the third layer.

Abstract: This invention provides a tin-free steel sheet, having superior lacquer adhesion, comprising metallic chromium and chromium oxide coatings on a steel sheet, characterized in that the chromium oxide coating is controlled such that I.sub.Cr.sup.580 /(I.sub.Cr.sup.580 +I.sub.Cr.sup.660) has a value of 0.5 or more provided that I.sub.Cr.sup.580 is the percent transmission corresponding to ol linkage and I.sub.Cr.sup.660 is the percent transmission corresponding to oxo linkage in the infrared absorption spectrum of said chromium oxide coating as measured by Fourier transform infra-red spectroscopy.

Abstract: Tin-free steel sheets having improved resistance to retorting treatment are produced by chromium plating a steel sheet through cathodic electrolysis in a chromium ion-containing aqueous solution to form a metallic chromium coating, reversely electrolyzing the chromium plated steel sheet by a successive anodizing treatment in the same solution, and subjecting the sheet to an electrolytic chromate treatment in another aqueous solution of chromic acid, a chromate or dichromate. The chromium plating and reverse electrolysis should be carried out so as to satisfy the equations:x+1.ltoreq.y.ltoreq.x+41.ltoreq.x.ltoreq.6where y and x are the quantities of hydrated chromium oxides present on one surface of the steel sheet after the chromium plating step and after the reverse electrolysis step, respectively, as expressed in mg (in terms of metallic chromium) per square meter of the surface.

Abstract: Tin-free steel sheets exhibiting improved retorting resistance with respect to paint adhesion are produced by chromium plating a steel sheet through cathodic electrolysis in a chromium ion-containing solution, reversely electrolyzing the sheet by a successive anodizing treatment in said solution, and subjecting the sheet to an electrolytic treatment in an aqueous chromate solution. The SO.sub.4.sup.-- concentration of the chromate solution used in the electrolytic chromate treatment should be limited to the range of 0.01 to 0.10 gram per liter of the solution.

Abstract: A high adhesion uniform forsterite insulating film can be formed on the surface of a grain-oriented silicon steel sheet by the application of an annealing separator consisting mainly of magnesia having a narrow activity distribution defined by the citric acid activity of the magnesia which varies depending upon the variation of final reaction ratio of the magnesia as determined by the method for measuring the citric acid activity of magnesia, where the final reaction ratio of the magnesia is the ratio of that amount of the magnesia which finally reacts with citric acid to the total amount of magnesia mixed with the citric acid.

Abstract: A highly adhesive and uniform insulating film can be formed on a grain-oriented silicon steel sheet without deteriorating the iron loss of the steel sheet by the use of a magnesia series annealing separator containing a strontium compound.

Abstract: A heat-resistant insulating coating having a high adhesion can be formed on an oriented silicon steel sheet by the use of an aqueous coating dispersion containing colloidal silica dispersed therein, at least one of monobasic phosphates of Mg, Al, Sr, Ba and Fe, at least one compound selected from chromic acid anhydride, chromate and dichromate, and at least one fine particle oxide selected from SiO.sub.2, Al.sub.2 O.sub.3 and TiO.sub.2 having a primary particle size of 70-500A and an apparent density of not higher than 100 g/l. The steel sheet having the coating is low in the iron loss and magnetostriction and shows good heat-resistant property.

Abstract: Forsterite insulating films having a high adhesion on an oriented silicon steel sheet are formed by a method wherein an annealing separator consisting mainly of magnesia is applied on surfaces of the oriented silicon steel sheet and the steel sheet is wound up into a coil-form and then annealed at high temperatures to form forsterite insulating films, which is characterized by that the content of water carried into the coil together with the annealing separator is controlled depending upon the content of CaO component carried into the coil together with the annealing separator.

Abstract: A forsterite insulating film having a good adhesion property to a grain-oriented silicon steel sheet with a high magnetic induction is composed of forsterite grains having a mean grain size of not more than 0.7 .mu.m. The forsterite insulating film is formed by annealing a coil of a cold rolled silicon steel strip having a final gauge in an annealing furnace under an inert gas atmosphere at a constant temperature keeping stage of 800.degree.-920.degree. C so as to fully develop secondary recrystallized grains and then under hydrogen gas atmosphere at a temperature rising stage up to 1,150.degree.-1,250.degree. C and a constant temperature keeping stage of 1,150.degree.-1,250.degree. C during the final annealing, provided that an average dew point of the atmosphere is within a range of -20.degree. C to +20.degree. C in the temperature rising stage up to 1,150.degree.-1,250.degree. C and not more than +10.degree. C in the constant temperature keeping stage of 1,150.degree.-1,250.degree. C.

Abstract: A uniform and high adhesive heat-resistant insulating film can be formed on a silicon steel sheet by applying an annealing separator consisting mainly of magnesia and containing 1-10% of titanium oxide having such a particle size that at least 99.5% of the agglomerated particles passes through 325-mesh sieve and having a dispersion degree in water of at least 85%.