Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Usui Co., Ltd.

Denso Corporation

Usui Kokusai Sangyo Kaisha Limited

Taizo Makino

Hitoshi Matsumoto

Yutaka Neishi

Tatsuya Masuda

Masashi Higashida

Naoki Matsui

Yoshihiro Tanimura

Kouji Morita

Masahiro Yamazaki

Yuichiro Yamamoto

Osamu Endo

Naomitsu Mizui

Katsunori Nagao

Naoki Serizawa

Tsugumi Yamazaki

Toshimasa Itou

Naoyuki Sashima

Yutaka Wakasu

Yuji Arai

Toshiyuki Hata

Tomohiko Omura

Tatsuya Hasegawa

Yukiteru Takeshita

Masato Yuya

Tadashi Nishiwaki

Takayuki Kamimura

Motoki Takasuga

Tomomitsu Fukuoka

Toshimasa Ito

Hiroaki Kondo

Chihiro Kozuka

Tsutomu Okuyama

Kiyonobu Sugae

Yoshiro Tanimura

A steel pipe for a fuel injection pipe has a chemical composition consisting of, by mass %: C: 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.020% or less, S: 0.0100% or less, O: 0.0040% or less, Ca: 0.0010% or less, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr: 0 to 1.00%, Mo: 0 to 1.00%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, and the balance: Fe and impurities. The metal micro-structure consists substantially of tempered martensite, or tempered martensite and tempered bainite. A prior-austenite grain size number is 9.0 or more. The hardness is within the range of 350 to 460 HV1. When a maximum value of a square root of an area of inclusions observed in a cross section perpendicular to a longitudinal direction of the steel pipe is taken as a(n=1 to 20), a maximum value aof ais 30.0 μm or less, and an average value aof ais 40% or more of a.

Steel pipe for fuel injection pipe, and fuel injection pipe using same

The railway axle according to this disclosure has a pair of fitting portions and which each include a fitting portion hardened layer and a base metal portion, and a center parallel portion which includes a center parallel portion hardened layer and the base metal portion. The base metal portion has the chemical composition described in the description. In a region having the Vickers hardness of 480 HV or more in the center parallel portion hardened layer, a dislocation density ρ obtained based on a CoKα characteristic X-ray diffraction result is 2.5×10mor less, a half-value width B of the (211) diffraction plane is 1.34 degrees or less, and the dislocation density ρ and the half-value width B of the (211) plane obtained by X-ray diffraction satisfy Formula (1).(−4.8×10+8.5×10)/ρ≥1.00  (1)

Railway axle

A steel pipe for a fuel injection pipe has a chemical composition consisting of, by mass %: C: 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.020% or less, S: 0.0100% or less, O: 0.0040% or less, Ca: 0.0010% or less, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr: 0 to 1.00%, Mo: 0 to 1.00%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, and the balance: Fe and impurities. The metal micro-structure consists substantially of tempered martensite, or tempered martensite and tempered bainite. The hardness is within the range of 350 to 460 HV1. A lattice spacing of a (211) diffraction plane measured by CoKα characteristic X-ray diffraction is 1.1716 Å or less, and a half-value width of the (211) diffraction plane is 1.200° or less. The number density of cementite having a diameter of 50 nm or more is 20/μmor less.

Provided is a rail vehicle axle having an excellent fatigue limit and notch factor. A rail vehicle axle according to the present embodiment has a chemical composition consisting of, in mass %, C: 0.20 to 0.35%, Si: 0.20 to 0.65%, Mn: 0.40 to 1.20%, P: 0.020% or less, S: 0.020% or less, Sn: 0.07 to 0.40%, N: 0.0200% or less, Cu: 0 to 0.30%, Ni: 0 to 0.30%, Cr: 0 to 0.30%, Mo: 0 to 0.08%, Al: 0 to 0.100%, V: 0 to 0.060%, and Ti: 0 to 0.020%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2):0.58≤C+Si/8+Mn/5+Cu/10+Cr/4+V≤0.67  (1)Si+0.9Cr≥0.50  (2)

Rail vehicle axle

A steel pipe has a composition consisting, by mass percent, of, C: 0.12 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.3 to 2.0%, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr 0 to 1.0%, Mo: 0 to 1.0%, Cu: 0 to 0.5%, Ni: 0 to 0.5%, V: 0 to 0.15%, and B: 0 to 0.005%, the balance being Fe and impurities. As impurities, contents are Ca: 0.001% or less, P: 0.02% or less, S: 0.01% or less, and O: 0.0040% or less. The micro-structure is tempered martensitic or tempered martensite and tempered bainite, in which a prior-austenite grain size number is 10.0 or more. Tensile strength is TS 800 MPa or higher. Critical internal pressure is [0.3'TS′a] or more, a=[(D/d)−1]/[0.776′(D/d)], D: pipe outer diameter (mm), d: pipe inner diameter (mm).

Steel pipe for fuel injection pipe and fuel injection pipe using the same

A steel pipe for fuel injection pipe has a tensile strength of 500 to 900 MPa and a yield ratio of 0.50 to 0.85, and has a critical internal pressure (IP) satisfying [IP&#x2265;0.41&#xd7;TS&#xd7;&#x3b1;] (&#x3b1;=[(D/d)&#x2212;1]/[0.776&#xd7;(D/d)], where TS: tensile strength (MPa) of the steel pipe, D: steel pipe outer diameter (mm), and d: steel pipe inner diameter (mm)), wherein a circumferential-direction residual stress on an inner surface of the pipe is &#x2212;20 MPa or lower after the steel pipe is split in half in a pipe axis direction.

Steel pipe for fuel injection pipe and method for producing the same

Provided is a rail vehicle axle having an excellent fatigue limit and notch factor. A rail vehicle axle according to the present embodiment has a chemical composition consisting of, in mass %, C: 0.20 to 0.35%, Si: 0.20 to 0.65%, Mn: 0.40 to 1.20%, P: 0.020% or less, S: 0.020% or less, Cu: 0 to 0.30%, Ni: 0 to 0.30%, Cr: 0 to 0.30%, Mo: 0 to 0.08%, Al: 0 to 0.100%, N: 0.0200% or less, V: 0 to 0.060%, and Ti: 0 to 0.020%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2):0.58&#x2264;C+Si/8+Mn/5+Cu/10+Cr/4+V&#x2264;0.67&#x2003;&#x2003;(1)Si+0.9Cr&#x2265;0.50&#x2003;&#x2003;(2)

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

Rolled steel bar for hot forging consisting, by mass percent, of C: 0.25-0.50%, Si: 0.40-1.0%, Mn: 1.0-1.6%, S: 0.005-0.035%, Al: 0.005-0.050%, V: 0.10-0.30%, N: 0.005-0.030% with the balance being Fe and impurities, i.e., P: 0.035% or less and O: 0.0030% or less, wherein Fn1=C+Si/10+Mn/5+5Cr/22+1.65V&#x2212;5S/7 is 0.90 to 1.20. The predicted maximum width of nonmetallic inclusions at the time when a cumulative distribution function obtained by extreme value statistical processing by taking the width of nonmetallic inclusion in an R/2 part of a longitudinal cross section of the steel bar as W (mm) is 99.99% is 100 &#x3bc;m or narrower. The number density of sulfides each having a circle-equivalent diameter of 0.3 to 1.0 &#x3bc;m observed per unit area of the R/2 part of a transverse cross section of the steel bar is 500 pieces/mmor higher.

Rolled steel bar for hot forging, hot-forged section material, and common rail and method for producing the same

A rolled steel bar for hot forging consisting, by mass percent, of C: 0.25-0.50%, Si: 0.40-1.0%, Mn: 1.0-1.6%, S: 0.005-0.035%, Al: 0.005-0.050%, V: 0.10-0.30%, and N: 0.005-0.030%, and the balance of Fe and impurities, i.e., P: 0.035% or less and O: 0.0030% or less, wherein Fn1=C+Si/10+Mn/5+5Cr/22+1.65V&#x2212;5S/7 is 0.90 to 1.20. The predicted maximum width of nonmetallic inclusions at the time when a cumulative distribution function obtained by extreme value statistical processing by taking the width of nonmetallic inclusion in an R/2 part of a longitudinal cross section of the steel bar as W (&#x3bc;m) is 99.99% is 100 &#x3bc;m or narrower. The number density of sulfides each having a circle-equivalent diameter of 0.3 to 1.0 &#x3bc;m observed per unit area of the R/2 part of a transverse cross section of the steel bar is 500 pieces/mmor higher.

Hot-forged section material and common rail

A rolled steel bar has a composition consisting, by mass percent, of C: 0.27 to 0.37%, Si: 0.30 to 0.75%, Mn: 1.00 to 1.45%, S: 0.008% or more and less than 0.030%, Cr: 0.05 to 0.30%, Al: 0.005 to 0.050%, V: 0.200 to 0.320%, and N: 0.0080 to 0.0200%, the balance being Fe and impurities. The contents of P, Ti and O in the impurities are, by mass percent, P: 0.030% or less, Ti: 0.0040% or less, and O: 0.0020% or less. Y1 expressed by the formula &#x3c;1&#x3e; is 1.05 to 1.18.Y1=C+(1/10)Si+(1/5)Mn+(5/22)Cr+1.65V&#x2212;(5/7)S&#x2003;&#x2003;&#x3c;1&#x3e;. C, Si, Mn, Cr, V, and S in the formula represent mass percent of the elements. A hot-forged part having a tensile strength of 900 MPa or higher and a transverse endurance ratio of 0.47 can be obtained by the rolled steel bar.

Rolled steel bar for hot forging

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Tokyo, Japan

Taizo Makino