Sumitomo Metal Industries, Inc.

Nippon Stainless Steel Co., Ltd.

Air Water Nv Inc.

Hisao Fujikawa

Shunichiro Akiyama

Yoshiaki Shida

Taishi Moroishi

Nobuyuki Maruyama

Junichiro Murayama

Yuji Shoji

Masamichi Kowaka

Masao Koike

Morihiro Fujita

Hirofumi Makiura

Atsushi Miyamoto

Isamu Koizumi

Provide a metal surface reforming method enabling metallic products with superior characteristics such as surface hardness, heat resistance, corrosion resistance, high temperature oxidation, high temperature corrosion, and environmental corrosion and the like. Halogenation treatment of heating and retaining a base material in an atmosphere containing a halogen based gas is performed on a base material of iron based metal or nickel based metal, then nitride processing of heating and retaining the halogenated base material described above in an atmosphere containing a nitrogen source gas is performed, then chromizing treatment is performed by placing the nitrided base material in a powder containing metal chromium powder to form a surface reformed layer on the base material described above. These metallic products obtained have high hardness, superior heat resistance and corrosion resistance, and exhibit superior performance in high temperature oxidation, high temperature corrosion, erosion, and cavitation and the like environments. Further, the metallic products described above exhibit superior performance in acid or alkali environments, neutral environments, and corrosive environments such as chlorides like salt water.

Method for altering surface of metal, and metallic product

A flexible tube for the exhaust system of an automobile made from a stainless steel is disclosed, which consists essentially of, by weight %:

Flexible tube for automotive exhaust systems

A corrosion-resistant steel tube such as a sheath heater steel tube and boiler tube which exhibit improved resistance to dry corrosion under high temperature dry-corrosive conditions in the presence of chlorides is disclosed. The steel consists essentially of, in % by weight:

Sheath heater

The present invention relates to the austenitic steel having improved resistance to oxidation at the high temperature, comprising not more than 0.10% C, 0.1-5.0% Si, not more than 3% Mn, 7-45% Ni, 15-30% Cr and sulfur content being restricted to not more than 0.003%. According to the present invention, by limiting the sulfur content in the austenitic steel to not more than 0.003%, preferably to not more than 0.0015%, the heat-resisting steel material which can show improved resistance to oxidation under severe conditions including repeated heating to high temperatures and cooling to room temperature is provided.

High temperature oxidation resistant austenitic steel

A process for producing heat-resistant ferritic stainless steel sheet which exhibits improved toughness and productivity is disclosed. The process comprises the following steps:

Process for producing heat-resistant ferritic stainless steel sheet

Herein disclosed is a low carbon austenitic steel having an improved resistance to stress corrosion cracking. The austenitic steel consists essentially of, by weight; less than 0.029% of carbon; 1.5 to 4.0% of silicon; 0.1 to 3.0% of manganese; 23 to 45% of nickel; 20 to 35% of chromium; 0.5 to 4.0% of vanadium; titanium in an amount of at least 5 times carbon content and up to 1% of the total composition, and/or niobium in an amount of at least 7 times carbon content and up to 1% of the total composition, and/or zirconium in an amount of at least 7 times carbon content and up to 1% of the total composition, and/or tantalum in an amount of at least 7 times carbon content and up to 2% of the total composition, and/or tungsten in an amount of at least 5 times carbon content and up to 2% of the total composition, the total amount of titanium and/or niobium and/or zirconium and/or tantalum and/or tungsten being in the range of at least 5 times carbon content and up to 2% of the total composition; if desired, copper and/or molybdenum in a total amount of 0.3 to 4%; and the balance of iron. This steel has outstanding utility as the materials of heat exchangers or pipes for generation of steam in nuclear reactors.

Low carbon Ni-Cr austenitic steel having an improved resistance to

A ferritic stainless steel having improved weldability and oxidation resistance, consisting essentially of 11.0 - 20.0% by weight of Cr, less than 0.10% by weight of C, less than 1.5% by weight of Si, less than 1.5% by weight of Mn, less than 1.5% by weight of Zr, the ratio of (Zr%)/(C% + N%) being higher than 7, and the balance of Fe, and the nitrogen amount being restricted to less than 0.015% by weight.

Ferritic stainless steel having improved weldability and oxidation

Herein disclosed is an Ni-Cr-Fe alloy being substantially in the single phase of austenite and improved in resistance to stress corrosion cracking. The alloy contains, by weight; 0.03 to 0.12% of carbon; 0.2 to 4% of silicon; 0.1 to 3% of manganese; 12 to 45% of nickel; 15 to 35% of chromium; vanadium and/or aluminum, the total amount of vanadium and aluminum being in the range of 0.2 to 4.0%, titanium in an amount of at least 5 times the carbon content and up to 1% of the total composition, and/or niobium in an amount of at least 7 times the carbon content and up to 1% of the total composition, and/or zirconium in an amount of at least 7 times the carbon content and up to 1% of the total composition, and/or tungusten in an amount of at least 5 times the carbon content and up to 2% of the total composition, the total amount of titanium and/or niobium and/or zirconium and/or tungusten being in the range of 0.3 to 2%; if desired, copper and/ or molybdenum in a total amount of 0.3 to 4%; and the balance of iron. This alloy has outstanding utility as structural material of heat exchanger, such as U-shaped tube of the nuclear reactor.

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Nishinomiya, Japan

Hisao Fujikawa