Abstract: An object of the present invention is to provide galling resistance to a threaded joint used for an oil well pipe. On a thread portion and a metallic sealing portion of the joint, there is provided a manganese phosphate chemical formation coating layer, or alternatively there are provided a nitriding layer of 1 to 20 .mu.m thickness and a manganese phosphate chemical formation coating layer of 5 to 30 .mu.m thickness, and also there is coated a solid lubricant which contains powder of molybdenum disulfide or tungsten disulfide and also contains one of epoxy resin, furan resin and polyamide resin as an essential component, and a ratio of composition is maintained at a specific value, so that a solid lubricant coating layer of 10 to 45 .mu.m thickness can be formed by heating.Due to the above surface treatment, even when the frequency of repetition of fastening and unfastening of the joint is increased, the occurrence of galling can be prevented over a long period of time.

Abstract: Disclosed are a process for hot-dip coating a steel material with a molten aluminum alloy according to a one-stage coating method using a flux which comprises removing an oxide layer on a steel material surface, conducting activating treatment, then coating a chloride flux solution and dipping the steel material in a molten aluminum alloy coating bath floated a fluoride-containing flux, thereby coating the steel material surface with aluminum alloy, or comprises removing an oxide layer on a steel material surface, adjusting surface roughness, conducting activating treatment and dipping the steel material in a molten Al--Zn--Si alloy or Al--Si alloy coating bath floated a flux added an iron component, thereby coating the steel material surface with Al--Zn--Si alloy or Al--Si alloy to adhere a large amount thereof and a aluminum alloy coating bath.

Abstract: A method for producing a composite steel strip having a high corrosion resistance comprises electroplating a steel strip substrate in an electroplating bath to codeposit a zinc-based metal matrix and corrosion-preventing fine solid particles. The particles comprise a core which may be, for example, chromate, phosphate, aluminum, molybdenum or titanium compounds and a thin coating membrane which may be, for example, SiO.sub.2, Al.sub.2 O.sub.3, ZrO.sub.2, TiO.sub.2 or a resin encapsulating the core. The core material is soluble in the electroplating bath while the coating membrane is substantially insoluble in the electroplating bath. The electroplating bath also contains an agent for promoting the codeposition of the zinc-based metal matrix and the particles, and may optionally include a number of additional fine particles which may be, for example, SiO.sub.2, TiO.sub.2, Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3, ZrO.sub.2, SnO.sub.2, or Sb.sub.2 O.sub.5.

Abstract: Disclosed is a coated steel sheet valuable for the production of a fuel vessel, in which a first covering layer comprising a Pb-Sn alloy as the main component is formed on a substrate comprising a steel sheet and an undercoat covering layer composed of at least one member selected from Ni, Co and Cu, which is formed on the surface of the steel sheet according to need, a second covering layer containing a compound containing Pb and P is formed on the first covering layer, a third covering layer containing at least one member selected from Sn, Ni and Co is formed on the second covering layer, and according to need, the surface portion of the third covering layer is modified with a treating liquid containing a phosphoric acid ion or a chromic acid ion. This coated steel sheet shows a highly improved corrosion resistance, forming processability, solderability, and weldability.

Abstract: An electroplated composite steel strip having a high corrosion resistance comprises a steel strip substrate and a corrosion resistant coating layer which comprises at least a base plating layer comprising a zinc-based metal matrix, a number of corrosion-preventing fine solid particles consisting essentially of core fine particles of, for example, chromate, phosphate, aluminum, molybdenum or titanium compounds, and encapsulated by very thin coating membranes consisting of, for example, SiO.sub.2, Al.sub.2 O.sub.3, ZrO.sub.2 or TiO.sub.2, and optionally a number of additional fine particles consisting essentially of, for example, SiO.sub.2, TiO.sub.2, Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3, ZrO.sub.2, SnO.sub.2 or Sb.sub.2 O.sub.5.

Abstract: A hot-dip aluminium coated steel sheet having excellent corrosion resistance and heat resistance, comprising a steel substrate containing 3 to 18% chromium, not more than 0.02% carbon, 0.1 to 1.5% manganese, 0.005 to 0.08% aluminium, not more than 0.1% silicon, with the balance being iron and unavoidable impurities, and aluminium coating on said sheet substrate. The coated sheet may further comprises a coating layer of nickel or nickel-iron alloy (Ni: 1 to 99%) beneath the aluminium coating, or an Al-Fe-Si-Ni-Cr alloy coating layer of 1 to 10.mu. in thickness and containing 0.05 to 5% nickel, 0.2 to 10% chromium, beneath the aluminium coating.

Abstract: The heat resistant subdivision of magnetic domains of a grain-oriented electrical steel sheet for improving the watt loss characterized by forming intruders therein is improved by pickling the steel sheet prior to the electroplating of the intrudable means. The partly exposed steel sheets are pickled by HNO.sub.3, H.sub.2 SO.sub.4 containing Fe.sup.3+, HCl containing Fe.sup.3+, and/or HBF.sub.4.

Abstract: A chromate surface treated steel sheet having very excellent paintability, corrosion resistance, and workability, more specifically surface treated steel sheets for paint coating, having very excellent properties, specifically with respect to corrosion resistance after paint coating, paint adhesion in services long after the paint coating (so-called secondary paint adhesion), corrosion resistance of paint coating defect portions, and resistance to secondary work cracking. The steel sheet contains not more than 0.15% carbon, 0.005 to 0.10% acid soluble aluminium, 0.5 to 20% chromium with the balance being iron and unavoidable impurities, and the chromate coating applied on the steel substrate comprises a metallic chromium layer in an amount ranging from 1 to 300 mg/m.sup.2, and a hydrated chromium oxide layer in an amount ranging from 5 to 50 mg/m.sup.2 in term of the metallic chromium contained therein.

Abstract: A plated composite steel strip having a high corrosion resistance comprises a steel strip substrate, a base electroplating layer comprising a Zn or Zn alloy matrix, substantially water-insoluble chromate particles, and additional fine or colloidal particles of SiO.sub.2, TiO.sub.2, Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3, ZrO.sub.2,SnO.sub.2 and/or Sb.sub.2 O.sub.5, and optionally, an additional electroplating layer formed on the base layer and consisting of Zn, Fe, Co, Ni, Mn and/or Cr and/or a surface coating layer containing at least an organic resinous surface layer and formed on the base, or an additional electroplating layer.

Abstract: A chromate treatment of metal coated steel sheets comprising subjecting the sheets to a cathodic electrolytic treatment to form a chromate film thereon and subjecting the sheet to an anodic electrolytic treatment to form an anodic electrolytic film on the chromate film and to convert the chromate film. The treatment is applicable to various metal coated steel sheets, such as those coated with zinc, zinc alloy, aluminum, aluminum alloy, lead and lead alloy, and is effective to improve the corrosion resistance of the sheets, the quality of paint coating applied on the sheets and the adaptability of the sheets to a cation electro-deposition paint coating.

Abstract: Coated steel sheet of high corrosion resistance comprises a sheet of steel containing not more than 0.1% by weight of carbon, 0.005 to 0.08% by weight of soluble aluminum and 0.2 to 20% by weight of chromium, the balance being iron and unavoidable impurities. The steel carries a nickel or nickel alloy layer formed on at least one surface thereof and having a thickness of 0.001 to 1.5 microns and a layer of tin formed on the nickel or nickel alloy layer and having a thickness of at least 0.05 micron. A method of producing it is also disclosed.

Abstract: Coating of steel articles with zinc-tin alloys by hot-galvanizing with addition of aluminum to improve the applicability and adhesion of the coating as well as the corrosion resistance, coated surface appearance and formabilities thereof.