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Nippon Steel Sumitomo Metal Corporation

Kiyotaka Akimoto

Yuichiro Shimizu

Atsushi Kobayashi

Susumu Maeda

Masao Kanayama

Masahiro Suzuki

Masato Yuya

Youichi Watanabe

Hideki Imataka

Ikuo Tani

Yuya Gyotoku

Katsushige Shimizu

Shunzou Umegaki

Yuichi Heishi

Keiji Yokose

A nitriding treatment method of a steel member, in which a nitriding treatment step is performed in which the steel member is subjected to a nitriding treatment in a nitriding gas atmosphere having a nitriding potential with which a &#x3b3;' phase or &#x3b5; phase iron nitride compound layer is generated on a surface of the steel member, and then, a passing step is performed in which the steel member is made to pass through an atmosphere at 425&#xb0; C. to 600&#xb0; C. where the iron nitride compound layer does not grow over five minutes or more, the iron nitride compound layer has the &#x3b3;&#x2032; phase uppermost surface layer, and the &#x3b3;&#x2032; phase is made to precipitate in the iron nitride compound layer by the proportion of 40% or more.

Nitriding treatment method of steel member

A manufacturing method of a nitrided steel member and the nitrided steel member include: performing a nitriding treatment on a steel member made of a carbon steel or an alloy steel in an atmosphere of a nitriding treatment gas in which when the total pressure is set to 1, a partial pressure ratio of NHgas is set to 0.08 to 0.34, a partial pressure ratio of Hgas is set to 0.54 to 0.82, and a partial pressure ratio of Ngas is set to 0.09 to 0.18, at a flow speed of the nitriding treatment gas set to 1 m/s or more, at 500 to 620&#xb0; C.; and thereby, forming an iron nitride compound layer having a thickness of 2 to 17 &#x3bc;m on a surface of the steel member.

Manufacturing method of nitrided steel member

A nitrided steel member including an iron nitride compound layer formed on a surface of a steel member having predetermined components, wherein: in X-ray diffraction peak intensity IFeN (111) of a (111) crystal plane of FeN and X-ray diffraction peak intensity IFeN (111) of a (111) crystal plane of FeN, which are measured on a surface of the nitrided steel member by X-ray diffraction, an intensity ratio expressed by IFeN (111)/{IFeN (111)+IFeN (111)} is 0.5 or more; Vickers hardness of the iron nitride compound layer is 900 or less, Vickers hardness of a base metal immediately under the iron nitride compound layer is 700 or more, and a difference between the Vickers hardness of the iron nitride compound layer and the Vickers hardness of the base metal is 150 or less; and a thickness of the iron nitride compound layer is 2 to 17 &#x3bc;m.

Nitrided steel member and manufacturing method thereof

The present invention provides a nitrided steel member and manufacturing method thereof. the nitrided steel member including: an iron nitride compound layer formed on a surface of a steel member made of carbon steel for machine structural use or alloy steel for machine structural use, in which with regard to X-ray diffraction peak intensity IFeN (111) of the (111) crystal plane of FeN and X-ray diffraction peak intensity IFeN (111) of the (111) crystal plane of FeN obtained by measuring a surface of the nitrided steel member by X-ray diffraction, an intensity ratio represented by IFeN(111)/{IFeN (111)+IFeN (111)} is 0.5 or more, and a thickness of the iron nitride compound layer is 2 to 17 &#x3bc;m.

A maraging steel is subjected to the aging to have a hardness of more than 500 Hv. A nitrided case is formed to have a depth that is about 20% to 50% to a &frac12; thickness of the maraging steel plate. An endless ring for a metal belt is constructed by the above maraging steel. According to methods of manufacturing the maraging steel and the endless ring, the nitrided case having the depth that is 20% to 50% of a distance from a plate surface to a center can be formed by executing an aging to have the hardness of more than 500 Hv, then executing a nitriding in the nitrogen atmosphere to which organic chloride is added.

Nitrided maraging steel and method of manufacture thereof

Growing community of inventors

Tokyo, Japan

Kiyotaka Akimoto