Jfe Steel Corporation

Ntn Corporation

Nhk Spring Co., Ltd.

Jfe Bars & Shapes Corporation

Sumihatsu Co., Ltd.

Kiyoshi Uwai

Takashi Iwamoto

Shigeru Endo

Kazukuni Hase

Minoru Honjo

Shinji Mitao

Yasumasa Hirai

Akira Tange

Takaaki Toyooka

Kazuhiko Yoshida

Isao Hirai

Kunikazu Tomita

Tatsumi Kimura

Keisuke Ando

Takayasu Takubo

Yasuhiro Omori

Hideto Kimura

Kohei Yoshino

Moriyasu Yamaguchi

Yuta Imanami

Katsutoshi Yamashita

Koei Tsuru

Keiichi Fujie

A high manganese content deformed reinforcing bar having an austenite single phase microstructure has excellent bending workability. A deformed reinforcing bar includes a chemical composition containing, in mass %, C: 0.7% or more and 1.2% or less, Si: 1.0% or less, Mn: 9% or more and 15% or less, Cr: 1.0% or less, P: 0.03% or less, and S: 0.05% or less, the balance consisting of Fe and inevitable impurities; and a microstructure comprising an austenite single phase. The ratio of the difference between the maximum and minimum hardness at a periphery of a cross-section perpendicular to the longitudinal direction with respect to a central average hardness is 15% or less. Two or more ribs extend in the longitudinal direction at equal intervals in a cross-sectional circumferential direction. The ratio of the difference between the maximum and minimum width of the ribs to the minimum width is 50% or less.

Deformed reinforcing bar

A mechanical structural component is a toothed component obtained by performing cold forging and carburizing treatment on a steel having a predetermined chemical composition, in prior austenite grains after the carburizing treatment, an area ratio of crystal grains of 50 &#x3bc;m or less is 80% or more, and an area ratio of crystal grains exceeding 300 &#x3bc;m is 10% or less, and a total helix deviation of teeth after the carburizing treatment satisfies Formula (1)()&#xd7;10&#x2264;5&#x2003;&#x2003;(1)where Bis a maximum total helix deviation in all teeth in mm, and L is a face width in mm.

Mechanical structural component and method for manufacturing same

A pearlitic rail includes a composition including in % by mass: 0.70% to 0.90% of C; 0.1% to 1.5% of Si; 0.01% to 1.5% of Mn; 0.001% to 0.035% of P; 0.0005% to 0.030% of S; 0.1% to 2.0% of Cr, remainder of the composition consisting of Fe and inevitable impurities. Surface hardness of a rail top is not less than HB 430, and hardness at a depth of 25 mm from a surface of the rail top is not less than HB 410.

Pearlitic rail and method for manufacturing pearlitic rail

The present invention provides a steel for nitrocarburizing having excellent mechanical workability before nitrocarburizing, and showing excellent fatigue properties after nitrocarburizing, which is suitable for applying in mechanical structural components for automobiles etc. prepared by adjusting the composition so that it contains in mass %, C: 0.01% or more and less than 0.10%, Si: 1.0% or less, Mn: 0.5% to 3.0%, P: 0.02% or less, S: 0.06% or less, Cr: 0.3% to 3.0%, Mo: 0.005% to 0.4%, V: 0.02% to 0.5%, Nb: 0.003% to 0.15%, Al: 0.005% to 0.2%, and Sb: 0.0005% to 0.02%, and the balance including Fe and incidental impurities, and setting the area ratio of bainite phase to the whole microstructure to more than 50%.

Steel for nitrocarburizing and nitrocarburized component, and methods for producing said steel for nitrocarburizing and said nitrocarburized component

Provided is high strength steel for springs that, compared to conventional high strength steel for springs, has excellent decarburization resistance and scale exfoliation property, by optimization of the added amounts of C, Si, Mn, and Cr as well as of Sb and Sn. The steel for springs contains C: more than 0.45 mass % and less than 0.65 mass %, Si: 0.15 mass % or more and 0.70 mass % or less, Mn: 0.10 mass % or more and 1.00 mass % or less, Cr: 0.20 mass % or more and 1.50 mass % or less, P: 0.025 mass % or less, S: 0.025 mass % or less, O: 0.0015 mass % or less, Sb: 0.010 mass % or more and less than 0.030 mass %, and Sn: 0.010 mass % or more and 0.030 mass % or less, under predetermined conditions.

Steel for spring, and method for producing spring

A method is provided with which a bearing steel, even when obtained from an ingot, is made to have a segregation part reduced in the degree of segregation and maximum inclusion diameter. The ingot contains 0.56-0.70 mass % C, 0.15-0.50 mass %, excluding 0.50 mass %, Si, 0.60-1.50 mass % Mn, 0.50-1.10 mass % Cr, 0.05-0.5 mass % Mo, up to 0.025 mass % P, up to 0.025 mass % S, 0.005-0.500 mass % Al, up to 0.0015 mass % O, and 0.0030-0.015 mass % N, with the remainder comprising Fe and incidental impurities. The ingot has a degree of segregation of 2.8 or less and a predicted value of the maximum diameter of inclusions present in 30,000 mmof the ingot, as calculated by extreme value statistics, of 60 &#x3bc;m or less.

Ingot for bearing and production process

Provided is bearing steel excellent in workability after spheroidizing-annealing and in hydrogen fatigue resistance property after quenching and tempering. The bearing steel has a chemical composition containing, by mass %: 0.85% to 1.10% C; 0.30% to 0.80% Si; 0.90% to 2.00% Mn; 0.025% or less P; 0.02% or less S; 0.05% or less Al; 1.8% to 2.5% Cr; 0.15% to 0.4% Mo; 0.0080% or less N; and 0.0020% or less O, which further contains more than 0.0015% to 0.0050% or less Sb, with the balance being Fe and incidental impurities, to thereby effectively suppress the generation of WEA even in environment where hydrogen penetrates into the steel, so as to improve the roiling contact fatigue life and also the workability such as cuttability and forgeability of the material.

Bearing steel being excellent both in workability after spheroidizing-annealing and in hydrogen fatigue resistance property after quenching and tempering

Provided is bearing steel excellent in post spheroidizing-annealing workability and in post quenching-tempering hydrogen fatigue resistance property. The bearing steel has a chemical composition containing, by mass %: 0.85% to 1.10% C; 0.30% to 0.80% Si; 0.90% to 2.00% Mn; 0.025% or less P; 0.02% or less S; 0.05% or less Al; 1.8% to 2.5% Cr; 0.15% to 0.4% Mo; 0.0080% or less N; 0.0020% or less O; and the balance being Fe and incidental impurities, to thereby effectively suppress the generation of WEA even in environment where hydrogen penetrates into the steel, so as to improve the rolling contact fatigue life and also the workability such as cuttability and forgeability of the material.

Bearing steel being excellent both in post spheroidizing-annealing workability and in post quenching-tempering hydrogen fatigue resistance property

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

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Tokyo, Japan

Kiyoshi Uwai