Jfe Steel Corporation

Ntn Corporation

Jtekt Corporation

Metawater Co., Ltd.

Hideto Kimura

Kazukuni Hase

Takaaki Toyooka

Tatsuro Katsumura

Minoru Honjo

Takashi Iwamoto

Shunsuke Sasaki

Kazuhiko Yoshida

Isao Hirai

Kunikazu Tomita

Masao Goto

Katsuyuki Ichimiya

Takayasu Takubo

Kiyoshi Uwai

Kohei Yoshino

Hisashi Harada

Hisato Nishisaka

Takaaki Iguchi

Akira Gotou

Kosuke Kamiya

Takaaki Kanagawa

Masuo Inoue

Naohiro Mizuguchi

Ayaka Koyano

Takahide Kawamura

An equipment line for manufacturing a seamless steel tube includes a steel heating device, a piercing device that pierces the steel into a hollow steel tube, a rolling mill that forms the hollow steel tube into a seamless steel tube having a predetermined shape, and a cooling system arranged between the heating device and the piercing device or between the piercing device and the rolling mill.

Equipment line for manufacturing seamless steel tube or pipe and method of manufacturing high-strength stainless steel seamless tube or pipe for oil wells using the equipment line

A plug for rolling of a seamless steel pipe, the plug having an oxide layer composed of a cobalt-base oxide on a surface of a coating layer formed by coating a surface of a base metal with cobalt or a cobalt-base alloy, a method for manufacturing the plug and a method for manufacturing a seamless steel pipe using the plug.

Plug for rolling of seamless steel pipe, method for manufacturing the same and method for manufacturing seamless steel pipe using the same

Disclosed is high strength spring steel that can limit the depth of pitting occurring when corroded and therefore possesses high strength as well as excellent pitting corrosion resistance and corrosion fatigue property, with a composition containing: C: greater than 0.35 mass % and less than 0.50 mass %; Si: greater than 1.75 mass % and less than or equal to 3.00 mass %; Mn: 0.2 mass % to 1.0 mass %; Cr: 0.01 mass % to 0.04 mass %; P: 0.025 mass % or less; S: 0.025 mass % or less; Mo: 0.1 mass % to 1.0 mass %; and O: 0.0015 mass % or less, under a condition that a PC value calculated by PC=4.2&#xd7;([C]+[Mn])+0.1&#xd7;(1/[Si]+1/[Mo])+20.3&#xd7;[Cr]+0.001&#xd7;(1/[N]) is greater than 3.3 and equal to or less than 8.0. Also disclosed is a preferred method for manufacturing the same.

Spring steel and method for manufacturing the same

Disclosed is high strength spring steel that can limit the depth of pitting occurring when corroded and therefore possesses high strength as well as excellent pitting corrosion resistance and corrosion fatigue property, with a composition containing: C: greater than 0.35 mass % and less than 0.50 mass %; Si: greater than L75 mass % and less than or equal to 3.00 mass %; Mn: 0.2 mass % to 1.0 mass %; Cr: 0.01 mass % to 0.04 mass %; P: 0.025 mass % or less; S: 0.025 mass % or less; Mo: 0.1 mass % to 1.0 mass %; and 0: 0.0015 mass % or less, under a condition that a PC value calculated by PC=4.2&#xd7;([C]+[Mn])+0.1&#xd7;(1/[Si]+1/[Mo])+20.3&#xd7;[Cr]+0.001&#xd7;(1/[N]) is greater than 3.3 and equal to or less than 8.0. Also disclosed is a preferred method for manufacturing the same.

A method is directed to a production of a bearing device for a wheel including an inner member and an outer member rotatable relative to each other through a plurality of rolling elements, in which a component part forming one of the inner member and the outer member is a hot forged product. In the practice of this method, during or at the end of a hot forging step for hot forging the component part, a portion of the component part is cooled by spraying a coolant or by controlling an atmospheric temperature, to thereby render a matrix of the component part to represent a standard structure and render a surface portion of the component part to represent a non-standard structure.

Process for producing bearing device for wheel

A steel part having a long rolling contact fatigue life and capable of further increasing the life of a bearing under severer using condition than usual conditions. The steel part includes steel having a composition containing 0.7% by mass to 1.1% by mass of C, 0.5% by mass to 2.0% by mass of Si, 0.4% by mass to 2.5% by mass of Mn, 1.6% by mass to 5.0% by mass of Cr, 0.1% by mass to less than 0.5% by mass of Mo, 0.010% by mass to 0.050% by mass of Al, less than 0.0015% by mass of Sb as an impurity, and the balance composed of Fe and inevitable impurities, the steel being hardened and tempered. In the steel structure of a portion from the surface to a depth of 5 mm, residual cementite has a grain diameter of 0.05 to 1.5 &#x3bc;m, prior austenite has a grain diameter of 30 &#x3bc;m or less, and the ratio by volume of the residual austenite is less than 25%.

Method for producing steel part having long rolling contact fatigue life

A hot forging facility enabling the manufacture of a hot forged product excellent in fatigue properties and cold workability is provided. A heating furnace for heating a steel material and a hot forging apparatus for performing forging of the heated steel material are sequentially arranged on a transport line. A partially cooling apparatus/apparatuses for partially cooling a forged product after hot forging is provided on an exit side of the hot forging apparatus.

Hot forging facility

A hot forged product including hardened areas introduced by partial cooling after hot forging, and unhardened areas, wherein Vickers hardness Vof the hardened areas on the surface and Vickers hardness Vof the unhardened areas satisfy the following formula (1): (V&#x2212;V)/V: 0.1 to 0.8.

Hot forged product with excellent fatigue strength, method for making the same, and machine structural part made from the same

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Tokyo, Japan

Hideto Kimura