Jfe Steel Corporation

Other

Nkk Corporation

Sony Corporation

Reiko Sugihara

Yasushi Tanaka

Hideki Matsuoka

Tatsuhiko Hiratani

Shin Ishikawa

Tetsuyuki Nakamura

Kenji Tahara

Kazuma Mori

Kunio Fukuda

Yoshimasa Funakawa

Takeshi Yokota

Yoshihiko Ono

Nobusuke Kariya

Hiroaki Kato

Hidetaka Kawabe

Satoshi Kodama

Kazunori Tahara

Yuji Yamasaki

Kenji Kawamura

Takayoshi Yano

Yoshinori Yomura

Yasuyuki Takada

Masahisa Fujikake

Tomohiro Ishii

Katsumi Kojima

Shinjiro Kaneko

Koichi Nakagawa

Takashi Kawano

Tadashi Inoue

Chikara Kami

Kazuhiro Seto

Mitsuyuki Fujisawa

Hiroki Nakamaru

Kaneharu Okuda

Hideyuki Kimura

Hidekazu Minami

Yoichiro Yamanaka

Hiroyuki Masuoka

Shusaku Takagi

Noriaki Kohsaka

Masataka Yoshino

Tetsuo Shimizu

Eiko Yasuhara

Takumi Tanaka

Yutaka Mihara

Teruo Takeuchi

Masahide Watanabe

Makoto Aratani

Masami Iwasaki

Masayoshi Kurihara

Manami Ichikawa

Kenichiro Takayanagi

Masamichi Okada

Ken-ichi Mitsuzuka

Tomonari Hiraguchi

Kazuki Nakazato

Toshihiro Kikuchi

Katsuhisa Yamauchi

Kenichi Mitsuzuka

Chohachi Sato

Shigeyuki Aizawa

Masahide Watabe

Keisuke Fukumizu

Hideya Matsumoto

Muhammad Febry

Keiji Ueda

Daigo Itoh

Nobuko Mineji

Noriko Kubo

Fumio Aoki

Masami Tsujimoto

Having a chemical composition (1) containing 0.15 mass % to 1.00 mass % of Nb, and (2) containing 0.0005 mass % to 0.0100 mass % of Mg, where (3) the Al content is controlled in a range of 0.55 mass % to 2.00 mass %, and (4) a relationship of 0.0004≤[Mg]/[Al]≤0.0050 is further satisfied.

Ferritic stainless steel for solid oxide fuel cell

Provided is a ferritic stainless steel in which cracking is unlikely to be caused in the vicinity of a weld zone by the stress due to expansion, contraction, and deformation due to the thermal effect of welding in the case of performing welding after deep drawing and which is excellent in corrosion resistance in the vicinity of the weld zone. The ferritic stainless steel has a composition containing C: 0.001% to 0.020%, Si: 0.01% to 0.30%, Mn: 0.01% to 0.50%, P: 0.04% or less, S: 0.01% or less, Cr: 18.0% to 24.0%, Ni: 0.01% to 0.40%, Mo: 0.30% to 3.0%, Al: 0.01% to 0.15%, Ti: 0.01% to 0.50%, Nb: 0.01% to 0.50%, V: 0.01% to 0.50%, Co: 0.01% to 6.00%, B: 0.0002% to 0.0050%, and N: 0.001% to 0.020% on a mass basis, the remainder being Fe and inevitable impurities. The composition satisfies 0.30%&#x2264;Ti+Nb+V&#x2264;0.60%.

Ferritic stainless steel

A high-strength steel sheet having a TS of 780 MPa or more, excellent stretch flangeability, and excellent in-plane anisotropy of TS is provided. A high-strength steel sheet comprises: a predetermined chemical composition; a steel microstructure including, in area fraction, ferrite: 20% or more and 50% or less, lower bainite: 5% or more and 40% or less, martensite: 1% or more and 20% or less, and tempered martensite: 20% or less, and including, in volume fraction, retained austenite: 5% or more, the retained austenite having an average grain size of 2 &#x3bc;m or less; and a texture having an inverse intensity ratio of &#x3b3;-fiber to &#x3b1;-fiber of 3.0 or less.

High-strength steel sheet and production method therefor

Provided is a ferritic stainless steel having excellent brazability and excellent corrosion resistance to condensed water in an environment in which the ferritic stainless steel is used for an exhaust heat recovery device or an EGR cooler. The ferritic stainless steel has a composition containing, in mass %, C: 0.025% or less, Si: 0.01% or more and less than 0.40%, Mn: 0.05 to 1.5%, P: 0.05% or less, S: 0.01% or less, Cr: 17.0 to 30.0%, Mo: 1.10 to 3.0%, Ni: more than 0.80% and 3.0% or less, Nb: 0.20 to 0.80%, Al: 0.001 to 0.10%, and N: 0.025% or less, with the balance being Fe and incidental impurities, and satisfying the following expression (1) and expression (2):C+N&#x2264;0.030%&#x2003;&#x2003;(1)Cr+Mo&#x2265;19.0%&#x2003;&#x2003;(2)

Provided is ferritic stainless steel having excellent brazeability and excellent corrosion resistance to condensed water in an environment in which the steel is used for an exhaust heat recovery device or an EGR cooler. A ferritic stainless steel has a chemical composition containing, by mass %, C: 0.025% or less, Si: 0.40% to 2.0%, Mn: 0.05% to 1.5%, P: 0.05% or less, S: 0.01% or less, Cr: 16.0% to 30.0%, Mo: 0.60% to 3.0%, Ni: 0.10% to 2.5%, Nb: 0.20% to 0.80%, Al: 0.001% to 0.15%, N: 0.025% or less, and the balance being Fe and inevitable impurities, in which relational expressions (1) and (2) below are satisfied.C+N&#x2264;0.030%&#x2003;&#x2003;(1),2Si+Ni&#x2265;1.0%&#x2003;&#x2003;(2),(in relational expressions (1) and (2), C, N, Si, and Ni each denote the contents (mass %) of the corresponding elements).

Provided is a ferritic stainless steel that has good corrosion resistance and which exhibits good brazeability when subjected to high-temperature brazing with a Ni-containing brazing filler metal. The ferritic stainless steel has a composition containing, in mass %, C: 0.003 to 0.020%, Si: 0.05 to 0.60%, Mn: 0.05 to 0.50%, P: 0.04% or less, S: 0.02% or less, Cr: 17.0 to 24.0%, Ni: 0.20 to 0.80%, Cu: 0.01 to 0.80%, Mo: 0.01 to 2.50%, Al: 0.001 to 0.015%, Nb: 0.25 to 0.60%, and N: 0.020% or less, with the balance being Fe and incidental impurities, the composition satisfying formula (1) below and formula (2) below,Cu+Mo&#x2265;0.30&#x2003;&#x2003;(1)4Ni&#x2212;(Si+Mn)&#x2265;0&#x2003;&#x2003;(2)(wherein Cu and Mo in formula (1) and Ni, Si, and Mn in formula (2) each represent the content (mass %) of the corresponding element).

A martensitic stainless steel sheet comprises a chemical composition containing, in mass %, C: 0.035% to 0.090%, Si: 0.01% to 1.0%, Mn: 0.01% to 0.90%, P: 0.050% or less, S: 0.050% or less, Cr: 10.0% to 14.0%, Ni: 0.01% to 0.40%, Al: 0.001% to 0.50%, V: 0.05% to 0.50%, and N: 0.050% to 0.20%, with the balance being Fe and inevitable impurities, wherein a content of C and a content of N in the chemical composition satisfy C %+N % 0.10% and N % C %, the number of precipitates with a major axis length of 200 nm or more in a surface layer of the martensitic stainless steel sheet is 25 or less per 100 &#x3bc;m, and the martensitic stainless steel sheet has a tensile strength of 1300 MPa or more, a proof stress of 1100 MPa or more, and an elongation of 8.0% or more.

Martensitic stainless steel sheet

Provided are a high-strength steel sheet and a method for manufacturing the steel sheet. The high-strength steel sheet has a specified chemical composition with the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 30% or more of a ferrite phase, 40% to 65% of a bainite phase and/or a martensite phase, and 5% or less of cementite, in which, in a surface layer that is a region within 50 &#x3bc;m from the surface in the thickness direction, the area ratio of a ferrite phase is 40% to 55% and the total area ratio of a bainite phase having a grain diameter of more than 5 &#x3bc;m and/or a martensite phase having a grain diameter of more than 5 &#x3bc;m is 20% or less, and a tensile strength is 980 MPa or more.

High-strength steel sheet and method for manufacturing the same

Provided are a high-strength steel sheet and a method for manufacturing the steel sheet. The high-strength steel sheet has a specified chemical composition with the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 25% or less of a ferrite phase, 75% or more of a bainite phase and/or a martensite phase, and 5% or less of cementite, in which, in a surface layer that is a region within 50 &#x3bc;m from the surface in the thickness direction, the area ratio of a ferrite phase is 5% to 20%, and a tensile strength is 1180 MPa or more.

A high-strength, cold-rolled steel sheet having a tensile strength of 980 MPa or more, the steel sheet having a chemical composition containing, by mass %, C: 0.070% to 0.100%, Si: 0.50% to 0.70%, Mn: 2.40% to 2.80%, P: 0.025% or less, S: 0.0020% or less, Al: 0.020% to 0.060%, N: 0.0050% or less, Nb: 0.010% to 0.060%, Ti: 0.010% to 0.030%, B: 0.0005% to 0.0030%, Sb: 0.005% to 0.015%, Ca: 0.0015% or less, Cr: 0.01% to 2.00%, Mo: 0.01% to 1.00%, Ni: 0.01% to 5.00%, Cu: 0.01% to 5.00%, and the balance being Fe and inevitable impurities, a metallurgical microstructure including a ferrite phase in an amount of 30% or more in terms of area fraction, at least one selected from a bainite phase and a martensite phase in an amount of 40% to 65% in total in terms of area fraction, and a cementite in an amount of 5% or less in terms of area fraction at a position located at &#xbc; of the thickness from the surface of the steel sheet, and a metallurgical microstructure including a ferrite phase in an amount of 40% to 55% in terms of area fraction at a position located at 50 &#x3bc;m in the thickness direction from the surface of the steel sheet and a method for manufacturing the steel sheet.

High-strength cold-rolled steel sheet and method for manufacturing the same

There is provided a high-strength steel sheet having a tensile strength (TS) of 900 MPa or more and excellent elongation, stretch flangeability, and bendability in a component system in which an expensive alloy element is not intentionally added. A high-strength steel sheet includes a composition including, on a mass % basis, C: 0.15 to 0.40%, Si: 1.0 to 2.0%, Mn: 1.5 to 2.5%, P: 0.020% or less, S: 0.0040% or less, Al: 0.01 to 0.1%, N: 0.01% or less, and Ca: 0.0020% or less, with the balance including Fe and incidental impurities. The high-strength steel sheet has a microstructure including 40% to 70% of a ferrite phase and a bainite phase in total, 20% to 50% of a martensite phase, and 10% to 30% of a retained austenite phase in terms of an area fraction relative to the entire microstructure.

High-strength steel sheet and method for producing the same

A Si-containing high-strength cold rolled steel sheet has a chemical composition comprising C: 0.02&#x2dc;0.3 mass %, Si: 0.8&#x2dc;2.0 mass %, Mn: 1.0&#x2dc;5.0 mass % and the remainder being Fe and inevitable impurities with a ratio of Si content to Mn content (Si/Mn) exceeding 0.4, and has a tensile strength TS of not less than 780 MPa, wherein a metallic structure of the steel sheet surface contains polygonal ferrite and/or bainitic ferrite having a Si concentration of not more than 3.0 mass % and a grain size of not more than 10 &#x3bc;m and does not have a Si-containing oxide layer on the steel sheet surface.

Si-containing high strength cold rolled steel sheet, method of producing the same, and automotive members

A cold-rolled steel sheet having a steel composition comprising, by mass %, 0.12% to 0.22% C, 0.8% to 1.8% Si, 1.8% to 2.8% Mn, 0.020% or less P, 0.0040% or less S, 0.005% to 0.08% Al, 0.008% or less N, 0.001% to 0.040% Ti, 0.0001% to 0.0020% B, 0.0001% to 0.0020% Ca, and Fe and incidental impurities. The steel sheet includes a microstructure in which ferrite and bainite phases are 50% to 70% of the total area, the average grain size of the ferrite and bainite phase is 1 to 3 &#x3bc;m, a tempered martensite phase is 25% to 45% of the total area, the average grain size of the tempered martensite phase is 1 to 3 &#x3bc;m, and a retained austenite phase is 2% to 10% of the total area.

High-strength cold-rolled steel sheet and method for producing the same

A steel sheet has a microstructure including ferrite phase: 40% to 60%, bainite phase: 10% to 30%, tempered martensite phase: 20% to 40%, and retained austenite phase: 5% to 20% by volume fraction, and satisfying a condition that a ratio of tempered martensite phase having major axis length &#x2266;5 &#x3bc;m to a total volume fraction of the tempered martensite phase is 80% to 100%.

A high-strength galvanized steel sheet contains C: 0.010% or more and 0.06% or less, Si: more than 0.5% and 1.5% or less, Mn: 1.0% or more and 3.0% or less, P: 0.005% or more and 0.1% or less, S: 0.01% or less, sol.Al: 0.005% or more and 0.5% or less, N: 0.01% or less, Nb: 0.010% or more and 0.090% or less, and Ti: 0.015% or more and 0.15% or less, on a mass percent basis. The Nb and C contents of the steel satisfy the relation of (Nb/93)/(C/12)&#x3c;0.20. C* satisfies 0.005&#x2266;C*&#x2266;0.025. Ferrite constitutes 70% by area ratio or more of the steel sheet. Martensite constitutes 3% by area ratio or more of the steel sheet. C*=C&#x2212;(12/93)Nb&#x2212;(12/48){Ti&#x2212;(48/14)N}, wherein C, Nb, Ti, and N denote the C, Nb, Ti, and N contents of the steel.

High strength galvanized steel sheet having excellent deep drawability and stretch flangeability and method for manufacturing the same

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Tokyo, Japan

Reiko Sugihara