Ricoh Company, Ltd.

Nippon Steel Corporation

Taiyo Yuden Co., Ltd.

Nippon Steel Sumitomo Metal Corporation

Sumitomo Metal Industries, Inc.

Sony Corporation

Nec Corporation

Usui Co., Ltd.

Other

Taiyu Yuden Co., Ltd.

Yuji Arai

Yutaka Ikebuchi

Toshihiko Shimokawa

Hiroshi Yoshinaga

Takahiro Imada

Yoshiki Yamaguchi

Arinobu Yoshiura

Hajime Gotoh

Masaaki Yoshikawa

Takuya Seshita

Toshio Koike

Kazuya Saito

Takayuki Seki

Ken Amemiya

Kenji Ishii

Hiromasa Takagi

Masanori Kawasumi

Naoki Iwaya

Shuutaroh Yuasa

Ryuuichi Mimbu

Akira Suzuki

Hiroyuki Nagashima

Kiyonori Tsuda

Kensuke Yamaji

Hiroshi Hosokawa

Takashi Ishiguro

Hiroshi Ono

Ippei Fujimoto

Tetsuo Tokuda

Masami Tomita

Satoshi Hatori

Keiichi Kondo

Shinji Yoshida

Kunio Kondo

Kazuhiko Umemura

Satoshi Narumi

Shuntaroh Tamaki

Takaaki Tawada

Hiroshi Ishii

Tadashi Ogawa

Teppei Kawata

Emiko Hamada

Takeshi Shintani

Nobuo Kuwabara

Masahiko Shakuto

Atsushi Sampe

Haruji Mizuishi

Kohichi Utsunomiya

Takeshi Yamamoto

Takeshi Uchitani

Yutaka Fukuchi

Tomohiko Omura

Satoshi Takano

Makoto Kikura

Yoshiyuki Kimura

Takeo Suda

Kazuosa Kuma

Kazuki Suzuki

Naoto Watanabe

Takatsugu Fujishiro

Tomoji Ishikawa

Eisaku Murakami

Kaoru Yoshino

Shinichi Kawahara

Hideki Zemba

Masato Yanagida

Shuji Tanaka

Takamasa Hase

Hideo Yoshizawa

Yutaka Takahashi

Hirokazu Ishii

Masahiro Yamazaki

Masahiko Satoh

Yoshio Hattori

Eiji Kurimoto

Hiroshi Saitoh

Toshihiro Sugiyama

Shinichi Namekata

Keiichi Nakamura

Kenji Yamamoto

Naohiro Kumagai

Toru Fujii

Yoshiki Hozumi

Toshio Watanabe

Akira Fujimori

Takaya Muraishi

Keitaro Shoji

Toru Takayama

Hiroshi Ogawa

Masayuki Yamamoto

Kenji Kobayashi

Hideki Kimura

Toshiya Satoh

Masayuki Yamane

Hitoshi Ishibashi

Takuya Matsumoto

Takanori Sato

Kazuhiro Shimoda

Eisuke Hori

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 steel material according to the present disclosure consists of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.05 to less than 0.80%, P: 0.030% or less, S: 0.0100% or less, Al: 0.100% or less, Cr: 0.30 to 1.50%, Mo: 0.25 to 2.00%, Ti: 0.001 to 0.015%, N: 0.0100% or less, O: 0.0050% or less, V: 0 to 0.05%, Nb: 0 to 0.010%, B: 0 to less than 0.0005%, Ca: 0 to 0.0100%, Mg: 0 to 0.0100%, and rare earth metal: 0 to 0.0100%, with the balance being Fe and impurities. In the steel material, the grain size number of prior-austenite grains is less than 7.0, Formula (1) to Formula (4) described in the specification are satisfied, the yield strength is 896 MPa or more, and the absorbed energy at −10° C. is 95 J or more.

Steel material

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.

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: more than 0.20 to 0.35%, Si: 0.05 to 1.00%, Mn: 0.02 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr: 0.40 to 1.50%, Mo: 0.30 to 1.50%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0100% or less and O: 0.0100% or less, with the balance being Fe and impurities, and satisfies Formula (1) and Formula (2) described in the description. The yield strength is 862 MPa or more. A numerical proportion of precipitates having an equivalent circular diameter within a range of 20 to 300 nm among precipitates having an equivalent circular diameter of 20 nm or more in the steel material is 0.85 or more.

Steel material suitable for use in sour environment

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr 0.60 to 1.80%, Mo: 0.80 to 2.30%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, Cu: 0.01 to 0.50%, Ni: 0.01 to 0.50%, N: 0.0020 to 0.0100% and O: 0.0020% or less, with the balance being Fe and impurities. The number density of BN in the steel material is 10 to 100 particles/100 μm. The yield strength of the steel material is 758 MPa or more.

Steel material and method for producing steel material

The seamless steel pipe according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.070%, Cr: 0.30 to 1.50%, Mo: 0.25 to 2.00%, Ti: 0.002 to 0.020%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, rare earth metal: 0.0001 to 0.0015%, Ca: 0.0001 to 0.0100%, N: 0.0100% or less and O: 0.0020% or less, with the balance being Fe and impurities, and satisfying Formula (1) described in the description. A predicted maximum major axis of inclusions is 150 μm or less, the predicted maximum major axis being predicted by means of extreme value statistical processing. The yield strength is within a range of 758 to 862 MPa.

Seamless steel pipe suitable for use in sour environment

A seamless steel pipe heat-treatment-finishing-treatment continuous facility includes: a heat treatment apparatus; a steel pipe inspection apparatus which performs a test for a surface defect and/or an inner defect of the seamless steel pipe, the steel pipe inspection apparatus being disposed downstream of the heat treatment apparatus; a main transfer mechanism which forms a main transfer path MT for transferring the seamless steel pipe, discharged from the heat treatment apparatus, to the steel pipe inspection apparatus disposed downstream of the heat treatment apparatus; and a first forced steel pipe-temperature reduction apparatus which forcibly reduces a temperature of the seamless steel pipe on the main transfer path MT, the first forced steel pipe-temperature reduction apparatus being disposed on the main transfer path MT at a position downstream of the heat treatment apparatus and upstream of the steel pipe inspection apparatus.

Seamless steel pipe heat-treatment-finishing-treatment continuous facility

A steel material according to the present disclosure has a chemical composition consisting of, in mass %: C: 0.15 to 0.45%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr 0.55 to 1.10%, Mo: 0.70 to 1.00%, Ti: 0.002 to 0.020%, V: 0.05 to 0.30%, Nb: 0.002 to 0.100%, B: 0.0005 to 0.0040%, N: 0.0100% or less, O: less than 0.0020%, and the balance being Fe and impurities, and satisfying Formula (1) described in the specification. A grain diameter of a prior-austenite grain is 15.0 μm or less, and an average area of precipitate which is precipitated in a prior-austenite grain boundary is 12.5×10μmor less. A yield strength is 758 to 862 MPa.

The steel pipe according to the present disclosure contains a chemical composition consisting of, in mass %, C: 0.25 to 0.50%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.30 to 1.50%, Mo: 0.25 to 3.00%, Ti: 0.002 to 0.050%, N: 0.0010 to 0.0100% and O: 0.0030% or less, with the balance being Fe and impurities. The steel pipe contains an amount of dissolved C within a range of 0.010 to 0.050 mass %. The tensile yield strength in the axial direction and the circumferential direction is 862 to 965 MPa, and the yield ratio in the axial direction is 90% or more. The tensile yield strength in the circumferential direction is 30 to 80 MPa higher than the compressive yield strength in the circumferential direction.

Steel pipe and method for producing steel pipe

The steel pipe according to the present disclosure contains a chemical composition consisting of, in mass %, C: more than 0.50 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0050% or less, Al: 0.005 to 0.100%, Cr: 0.30 to 1.50%, Mo: 0.25 to 3.00%, Ti: 0.002 to 0.050%, N: 0.0010 to 0.0100% and O: 0.0030% or less, with the balance being Fe and impurities. The steel pipe contains an amount of dissolved C within a range of 0.010 to 0.060 mass %. The tensile yield strength in the axial direction and the circumferential direction is 862 to 1069 MPa, and the yield ratio in the axial direction is 90% or more. The tensile yield strength in the circumferential direction is 30 to 80 MPa higher than the compressive yield strength in the circumferential direction.

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.20 to 0.35%, Si: 0.05 to 1.00%, Mn: 0.01 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr 0.25 to 0.80%, Mo: 0.20 to 2.00%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0020 to 0.0100% and O: 0.0100% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of precipitates having an equivalent circular diameter of 400 nm or more is 0.150 particles/&#x3bc;mor less. The yield strength is within a range of 655 to 965 MPa. A dislocation density &#x3c1; is 7.0&#xd7;10mor less.5&#xd7;Cr&#x2014;Mo-2&#xd7;(V+Ti)&#x2264;3.00&#x2003;&#x2003;(1)

The production method of a seamless steel pipe includes a heating step of heating an Nb-containing steel material to 800 to 1030&#xb0; C., a pipe-making step of producing a hollow shell by performing piercing-rolling or elongation-rolling on the Nb-containing steel material, by using a piercing mill including a plurality of skewed rolls, a plug disposed between the plurality of skewed rolls, and a mandrel bar, and a cooling step immediately after rolling, of carrying out cooling using a cooling liquid on a hollow shell portion that passes between rear ends of the plurality of skewed rolls, in the hollow shell, so as to reduce an outer surface temperature of the hollow shell portion to 700 to 1000&#xb0; C. within 15.0 seconds after the hollow shell portion passes between the rear ends of the plurality of skewed rolls.

Production method of seamless steel pipe

The steel material according to the present disclosure has a chemical composition consisting of, in mass %, C: 0.10 to 0.60%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr: 0.20 to 1.50%, Mo: 0.25 to 1.50%, V: 0.01 to 0.60%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.0020 to 0.0100%, and O: 0.0100% or less, with the balance being Fe and impurities. A dislocation density &#x3c1; is 3.5&#xd7;10mor less. Among fine precipitates, the numerical proportion of precipitates for which a ratio of the Mo content is not more than 50% is 15% or more. The yield strength is in a range of 655 to 1172 MPa.

A seamless steel pipe is provided that has a chemical composition which consists of, by mass %, C: 0.10 to 0.20%, Si: 0.05 to 1.0%, Mn: 0.05 to 1.2%, P&#x2264;0.025%, S&#x2264;0.005%, Cu&#x2264;0.20%, N&#x2264;0.007%, Ni: 0.20 to 0.50%, Cr: 0.30% or more and less than 0.50%, Mo: 0.30 to 0.50%, Nb: 0.01 to 0.05%, Al: 0.001 to 0.10%, B: 0.0005 to 0.0020%, Ti: 0.003 to 0.050%, V: 0.01 to 0.20%, a total of any one or more elements among Ca, Mg and REM: 0 to 0.025%, and the balance: Fe and impurities, and for which Pcm (=C+(Si/30)+(Mn/20)+(Cu/20)+(Ni/60)+(Cr/20)+(Mo/15)+(V/10)+5B)&#x2264;0.30. The steel micro-structure includes, in area %, tempered martensite &#x2265;90%. The tensile strength is 980 MPa or more, and a Charpy impact value at &#x2212;40&#xb0; C. using a 2 mm V-notch test specimen is 75 J/cmor more.

Seamless steel pipe and method for producing same

The steel material according to the present disclosure contains a chemical composition consisting of, in mass %, C: 0.20 to 0.50%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: 0.030% or less, S: less than 0.0050%, Al: 0.005 to 0.050%, Cr: 0.10 to 1.50%, Mo: 0.25 to 1.80%, Ti: 0.002 to 0.050%, Nb: 0.002 to 0.100%, B: 0.0001 to 0.0050%, N: 0.0070% or less and O: less than 0.0050% with the balance being Fe and impurities. A yield strength is within a range of 655 to 1069 MPa, and a yield ratio is 85% or more. A proportion of KAM values of 1&#xb0; or less is 30 area % or more.

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Kanagawa, Japan

Yuji Arai