Daidousanso Co., Ltd.

Daido Hoxan Inc.

Tadashi Hayashida

Kenzo Kitano

Masaaki Tahara

Haruo Senbokuya

Teruo Minato

A method of carburizing austenitic stainless steel comprising the steps of holding austenitic stainless steel in a fluorine- or fluoride-containing gas atmosphere with heating prior to carburizing and carburizing the austenitic stainless steel at a temperature not more than 680.degree. C. wherein said austenitic stainless steel is stable austenitic stainless steel having 1 to 6 weight % molybdenum or 13 to 25 weight % chromium, wherein a carburized hard layer having corrosion resistance superior to base material forms and austenitic stainless steel products obtained thereby.

Method of carburizing austenitic stainless steel and austenitic

A method of carburizing austenitic metal comprising the steps of holding austenitic metal in a fluoride-containing gas atmosphere with heating prior to carburizing and carburizing the austenitic metal at a temperature not more than 680.degree. C. and austenitic metal products obtained thereby.

Method of carburizing austenitic metal

A method for carburizing austenitic metal comprising fluorinating the austenitic metal and consecutive carburizing at a low temperature not more than 680.degree. C. A carburizing temperature can be lowered by such a fluorination. As a result, carbide of chrome component in the austenitic metal can be prevented from depositing. That is, much chrome component remains in the austenitic metal. Therefore, the austenitic metal surface can be hardened and also superior anti-corrosion property can be maintained.

The present invention relates to nickel alloy products with their surfaces nitrided and hardened which are formed by pressure casting nickel alloy material, and nitrided and hardened layers are formed in surface layers. Since the nitrided and hardened surfaces of the nickel alloy products according to the invention have much better corrosion resistance than iron products have, anticorrosion treatment such as plating is not required, and rich lubricity and excellent tightening property can be obtained without having seizure and scuffing phenomena.

Process of producing nitrided and hardened nickel alloy products

A loom guide bar blade for automatic weaving machinery such as an air or water jet loom wherein the surface of the blade which contacts yarn is nitrided to form a nitrided hardened layer. When this blade is used in automatic high-speed weaving machinery, wearing and the like at contacting points of the blade with the yarn are prevented. As a result yarn fluffing from its being abraded by a roughened blade surface is minimized.

Loom guide bar blade with its surface nitrided for hardening

Nickel alloy products with their surfaces nitrided and hardened

Nitrided stainless steel products having a base material of stainless steel containing austenitic stainless steel. At least a portion of the surface layer of the base material is composed of a nitrided hard layer in accordance with the following conditions (A) and (B):

Nitrided stainless steel products

A hard nitrided layer is formed on austenitic stainless steel by holding the austenitic stainless steel in a heated condition under a fluorine- or fluoride-containing atmosphere and then nitriding it so that a close uniform nitriding layer can be formed, resulting the remarkable improvement in the surface hardness of the above-mentioned austenitic stainless steel. The temperature in the above-mentioned nitriding treatment is set below 450.degree. C. so that high anti-corrosion property, originally inherent in austenitic stainless steel, can be retained without deterioration.

Method of nitriding austenitic stainless steel products

A method of nitriding nickel alloy comprising steps of holding nickel alloy in an atmosphere of fluorine- or fluoride-containing gas in a heated condition and holding the fluorinated nickel alloy in a nitriding atmosphere in a heated condition to provide the nickel alloy with improved surface hardness by forming a deep uniform nitrided layer on the surface of the nickel alloy.

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Osaka, Japan

Tadashi Hayashida