Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Honda Motor Co., Ltd.

Denso Corporation

Dowa Thermotech Co., Ltd.

Masato Yuya

Takahide Umehara

Hitoshi Matsumoto

Atsushi Kobayashi

Tatsuya Hasegawa

Susumu Maeda

Hideki Imataka

Yoshihiro Daito

Yuya Gyotoku

Satoru Okawa

Yutaka Neishi

Yoshihiro Tanimura

Taizo Makino

Tadashi Nishiwaki

Hiroaki Tahira

Masashi Higashida

Kouji Morita

Yuichiro Shimizu

Kiyotaka Akimoto

Kison Nishihara

Tatsuhiko Abe

Motoki Takasuga

Masao Kanayama

Yoshihiro Takitani

Toshimasa Ito

Tomomitsu Fukuoka

Shigefumi Nishitani

Yoshiro Tanimura

A crankshaft with improved seizure resistance is provided. A crankshaft having journalsand pinsincludes a compound layer containing iron and nitrogen on its surface, wherein, in the compound layer, for both the journalsand pins, the porosity area ratio of the thinner one of a region from the surface to a depth of 3.0 μm and a region across the total thickness of the compound layer is not higher than 10.0%, and both the journalsand pinshave such a surface geometry that the arithmetical mean deviation of the primary profile, Pa, is not larger than 0.090 μm.

Crankshaft and method of manufacturing the same

Provided are a roughly-shaped steel material for a nitrided part, and a nitrided part obtained by nitriding the roughly-shaped steel material for a nitrided part, having a determined chemical composition, in which the portion with a diameter or width ranging from 60 to 130 mm of the roughly-shaped steel material for a nitrided part has a microstructure at a depth of 14.5 mm from a surface including, in terms of area fraction: tempered martensite and tempered bainite in total: from 70 to 100%; remaining austenite: from 0 to 5%; and a balance: ferrite and perlite; and has a microstructure at a depth of 15 mm or more from the surface including, in terms of area fraction: tempered martensite and tempered bainite in total: from 0 to less than 50%; remaining austenite: from 0 to 5%; and a balance: ferrite and perlite.

Roughly-shaped steel material for nitrided part, and nitrided part

The present invention has as its technical problem the provision of a part excellent in contact fatigue strength or wear resistance in addition to the rotating bending fatigue strength. In the present invention, the contents of the constituents of the steel, in particular C, Mn, Cr, V, and Mo, are adjusted in accordance with the targeted properties and nitrided parts are prepared while controlling the nitriding potential.

Nitrided part

A nitrided steel part excellent in bending straightening ability and bending fatigue characteristic enabling reduction of size and decrease of weight of parts or enabling demand for high load capacities to be met, using as a material a steel material containing, by mass %, C: 0.2 to 0.6%, Si: 0.05 to 1.5%, Mn: 0.2 to 2.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: 0.05 to 0.5%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025%, and having a balance of Fe and impurities, having formed on the steel surface a compound layer of a thickness 3 &#x3bc;m or less comprising iron, nitrogen, and carbon and a hardened layer formed below the compound layer, and having an effective hardened layer depth of 160 to 410 &#x3bc;m.

Nitrided steel part and method of production of same

A nitrided steel part excellent in pitting resistance and bending fatigue characteristic enabling reduction of size and decrease of weight of parts or enabling demand for high load capacities to be met, using as a material a steel material containing, by mass %, C: 0.05 to 0.25%, Si: 0.05 to 1.5%, Mn: 0.2 to 2.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: over 0.5 to 2.0%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025%, having a balance of Fe and impurities, having formed on the steel surface a compound larger of a thickness 3 &#x3bc;m or less containing iron, nitrogen, and carbon and a hardened layer formed below the compound layer, and having an effective hardened layer depth of 160 to 410 &#x3bc;m.

A nitrided part and soft nitrided part with excellent wear resistance and pitting resistance and a nitriding method and soft nitriding method are provided, specifically, a nitrided part or soft nitrided part made by a steel material comprising, by mass %, C: 0.05 to 0.3%, Si: 0.05 to 1.5%, Mn: 0.2 to 1.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: 0.5 to 2.0%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025% and having a balance of Fe and impurities, wherein, the surface layer comprises a compound layer containing iron, nitrogen, and carbon and a nitrogen diffusion layer positioned below the compound layer, the compound layer comprises an &#x3b5; single phase, the &#x3b5; single phase has a thickness of 8 to 30 &#x3bc;m and a Vicker's hardness of 680 HV or more, and the &#x3b5; single phase has a volume ratio of pores of less than 10%.

Nitrided or soft nitrided part with excellent wear resistance and pitting resistance, and nitriding and soft nitriding method

A nitrided component has a chemical composition consisting of, by mass percent, C: 0.07-0.14%, Si: 0.10-0.30%, Mn: 0.4-1.0%, S: 0.005-0.030%, Cr: 1.0-1.5%, Mo: &#x2264;0.05% (including 0%), Al: 0.010% or more to less than 0.10%, V: 0.10-0.25%, optionally at least one element selected from Cu: &#x2264;0.30% and Ni: &#x2264;0.25%, [0.61Mn+1.11Cr+0.35Mo+0.47V&#x2264;2.30], and the balance of Fe and impurities. P, N, Ti and O among the impurities are P: &#x2264;0.030%, N: &#x2264;0.008%, Ti: &#x2264;0.005%, and O: &#x2264;0.0030%. The nitrided composition is suitable for use as an automobile ring gear. The nitrided component has a surface hardness of 650-900 HV, core hardness being &#x2265;150 HV, effective case depth of &#x2265;0.15 mm, has excellent bending fatigue strength and surface fatigue strength although the content of Mo is as low as &#x2264;0.05% and has a small amount of expansion caused by nitriding.

Nitrided component

An age-hardenable steel having a composition consisting of: C: 0.05 to 0.20%, Si: 0.01 to 0.50%, Mn: 1.5 to 2.5%, S: 0.005 to 0.08%, Cr: more than 0.50% and not more than 1.6%, Al: 0.005 to 0.05%, V: 0.25 to 0.50%, Mo: 0 to 1.0%, Cu: 0 to 0.3%, Ni: 0 to 0.3%, Ca: 0 to 0.005%, and Bi: 0 to 0.4%, the balance being Fe and impurities. Within the impurities, P&#x2264;0.03%, Ti&#x3c;0.005%, and N&#x3c;0.0080%, and [C+0.3Mn+0.25Cr+0.6Mo&#x2265;0.68], [C+0.1Si+0.2Mn+0.15Cr+0.35V+0.2Mo&#x2264;1.05], and [&#x2212;4.5C+Mn+Cr&#x2212;3.5V&#x2212;0.8Mo&#x2265;0.12]. The steel has hardness before aging of not more than 310 HV. After aging, the fatigue strength is not less than 480 MPa and absorbed energy at 20&#xb0; C. is not less than 12 J.

Age-hardenable steel

Provided is a non-thermal refined soft-nitrided component including chemical composition of a steel material of a base metal containing: in mass %, C: 0.25 to 0.40%; Si: 0.10 to 0.35%; Mn: more than 2.0% to 2.8% or less; N: 0.0030 to 0.0250%; Cu: 0 to 1.0%; Mo: 0 to 0.3%; Ni: 0 to 0.5%; Ti: 0 to 0.020%; and a balance being Fe and impurities, the impurities including P: 0.08% or less; S: 0.10% or less; Al: 0.05% or less; and Cr: less than 0.20%, wherein a Vickers hardness at a position of 0.05 mm from the surface is 400 to 480, a Vickers hardness at a position of 1.0 mm from the surface is 200 or more, and a compound-layer depth at a stress concentrated region is 5 &#x3bc;m or less. This non-thermal refined soft-nitrided component has an excellent bending straightening property and a high fatigue strength.

Non-thermal refined soft-nitrided component

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

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Tokyo, Japan

Masato Yuya