Nippon Steel Corporation

Toyota Jidosha Kabushiki Kaisha

Tatsuhiko Abe

Manabu Kubota

Satoru Okawa

Motoichi Murakami

Yuichiro Kajiki

Masato Yuya

Yusuke Morita

Takeshi Fukui

Yoko Sueyasu

Yusuke Inukai

A crankshaft with improved seizure resistance is provided. A crankshaft () is a crankshaft including journals () and pins (), having a chemical composition of, in mass %: 0.35 to 0.40% C; up to 0.70% Si; 1.00 to 2.00% Mn; up to 0.50% Cr; up to 0.050% Al; up to 0.020% N; up to 0.020% P; 0.005 to 0.200% S; and balance Fe and impurities, each of the journals () and pins () having a surface microstructure containing tempered martensite in not less than 80 volume % and a surface hardness not higher than HV 450.

Crankshaft

A crankshaft with improved fatigue strength is provided. A crankshaftincludes journals, pins, and fillets, each fillethaving a residual stress distribution where the residual stresses are compressive residual stresses from the surface down to a depth of at least 300 μm, the maximum value of the compressive residual stress being not lower than 1000 MPa, the surface roughness Rz being lower than 3.00 μm.

Crankshaft and method of manufacturing the same

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.

A crankshaft with improved seizure resistance is provided. A crankshaft includes a journal and a pin, each of the journal and pin having such a surface geometry that the arithmetical mean height of the primary profile, Pa, is 0.090 &#x3bc;m or smaller and the reduced peak height Rpk is 0.070 &#x3bc;m or smaller. As used herein, arithmetical mean height of a primary profile Pa is defined in JIS B 0601 (2001), and reduced peak height Rpk is defined in JIS B 0671 (2002).

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Tokyo, Japan

Tatsuhiko Abe