Nippon Steel Corporation

Satoshi Kado

Teruo Ikeno

Mikio Yamanaka

Hironobu Kawasaki

Saburo Ayusawa

Takashi Watanabe

Kotaro Yoshida

Taketomo Yamazaki

Yasuo Otoguro

Katsuhiko Yabe

Yasuhiko Miyoshi

Kazuhiro Masuda

Chuichi Kato

Tadao Azami

Tsuneyasu Watanabe

Tetsu Sakamoto

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+.

Surface treated steel materials

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.

Manganese surface coated steel materials

An austenitic heat-resistant steel which forms an oxide film mainly composed of Al.sub.2 O.sub.3 in a high-temperature oxidizing atmosphere, consisting essentially of not more than 0.2% of C, not more than 1.0% of Si, not more than 2.0% of Mn, 12 to 37% of Ni, 9 to 25% of Cr, more than 4.5 but not more than 6% of Al, and at least one member selected from the group consisting of Ti, Nb and Zr in a total amount of not more than 0.8%, with the balance being Fe; the .delta.-ferrite value of this steel, calculated from the formula set forth below, is from 0 to 7.9; this steel is removed of an internal oxide layer which has been formed just below the steel surface during hot working. ##EQU1## where Wi and Mi represent, respectively, the percent by weight and the atomic weight of Ti, Nb and Zr, and when the term ##EQU2## is negative this term is regarded as zero. This steel composition may contain one or more rare earth elements such as Y, Ce and La in a total amount of not more than 0.08%.

Austenitic heat-resistant steel which forms Al.sub.2 O.sub.3 film in

A stainless steel pipe having a surface layer with excellent resistance against vanadium pentoxide attack experienced upon boiler heating tubes for power generation, corrosion by sulfates, corrosion by chlorides experienced upon boiler heating tubes for various burning furnace and high-temperature gas corrosion experienced upon tubes for heating furnaces in the chemical industry, and also relates to methods for forming the surface layer.

Stainless steel products, such as sheets and pipes, having a surface

A ferritic stainless steel having high toughness both in the weld zone and the base metal comprising:

Ferritic stainless steel having excellent workability and high toughness

Surface treatment of weather-resistant steel by applying a liquid composition comprising 5 to 50% of Fe.sub.3 O.sub.4 + Fe.sub.2 O.sub.3, 0.01 to 5% of phosphoric acid, 0.01 to 10% of at least one selected from the consisting of Pb, Ni, Cu, P, Zn, Cr and their compounds, 3 to 30% of butyral resin, the balance being solvent by spraying or brushing. The surface treatment is effective for preventing the occurence of the initial rust formation of the steel and promoting a stable and dense protective rust against subsequent corrosion of the steel.

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Fujisawa, Japan

Satoshi Kado