Jfe Steel Corporation

Thyssenkrupp Steel Ag

Thyssenkrupp Steel Europe Ag

Taro Kizu

Yoshimasa Funakawa

Shunsuke Toyoda

Akimasa Kido

Tetsushi Tadani

Hiroshi Nakano

Tetsuo Yamamoto

Hiroshi Uchomae

Hiroshi Matsuda

Yasushi Tanaka

Yasunobu Nagataki

Kohei Hasegawa

Shigehiro Takajo

Koichiro Fujita

Akio Kobayashi

Masatoshi Kumagai

Takaaki Tanaka

Shusaku Takagi

Kenji Kawamura

Kenji Tahara

Sota Goto

Thomas Heller

Eiko Yasuhara

Shoji Kasai

Kazuhiro Hanazawa

Brigitte Hammer

Kazuhiko Yamazaki

Noriaki Moriyasu

Kazunori Tahara

Jian Bian

Rolf Bode

Günter Stich

Hidekazu Ookubo

Kana Sasaki

Yusuke Yasufuku

Tokunori Kanemura

Masato Shigemi

Shinji Yamazaki

Hideharu Koga

Masahide Morikawa

Brigitte Bode, Legal Representative

Shigeyuki Nabeshima

There is provided a galvanized steel sheet more highly excellent in terms of punchability. The steel sheet has a specified chemical composition and a microstructure including a ferrite phase and a tempered bainite phase in a total amount of 95% or more in terms of area ratio, in which the average grain diameter of the microstructure is 5.0 &#x3bc;m or less, the amount of Fe precipitated is 0.10 mass % or more, the amount of Ti, Nb, and V precipitated in the form of precipitates having a grain diameter of less than 20 nm is 0.025 mass % or more in terms of precipitate C equivalent, and half or more of precipitates having a grain diameter of less than 20 nm are formed at random.

Galvanized steel sheet and method for manufacturing the same

Provided is a high-strength hot-rolled coated steel sheet with excellent formability, A high-strength hot-rolled coated steel sheet has a constituent composition containing, in a mass percent, C: 0.03% to 0.15%, Si: 0.4% or less, Mn: 1.2% to 1.9%, Ti: 0.05% to 0.25%, B: 0.0005% to 0.0050%, P: 0.03% or less, S: 0.005% or less, Al: 0.005% to 0.4%, and N: 0.01% or less, the balance being Fe and incidental impurities. The total area fraction of one or more of ferrite and tempered bainite is 90% or more. The steel sheet has a structure in which the volume fraction of Ti carbides having particle sizes of 20 nm or less is 0.05 vol % or more.

High-strength hot-rolled coated steel sheet

A steel sheet has a composition containing, by mass %, C: 0.04% to 0.20%, Si: 0.6% to 1.5%, Mn: 1.0% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, N: 0.010% or less, one, two, or all of Ti, Nb, and V in an amount of 0.01% to 1.0% each, and the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 50% or more of ferrite, in which an average grain diameter at a position located 50 &#x3bc;m from a surface of the steel sheet in a thickness direction is 3000&#xd7;(tensile strength TS (MPa))&#x3bc;m or less, C precipitates having a grain diameter of less than 20 nm formed in steel is 0.010 mass % or more, and a amount of precipitated Fe is 0.03 mass % to 1.0 mass %, and a roughness Ra of 3.0 &#x3bc;m or less.

High-strength steel sheet and method of manufacturing the same

A high strength steel sheet having high strength such as a tensile strength of 780 MPa or more and having excellent blanking workability and stretch flangeability and a manufacturing method therefor are provided. A high strength steel sheet comprises: a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.6% to 2.0%, Mn: 1.3% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 2.0% or less, N: 0.010% or less, and one or more of Ti, Nb, and V: 0.01% to 1.0% each, with a balance being Fe and incidental impurities; a ferrite microstructure of 50% or more in area ratio; an amount of precipitated Fe of 0.04 mass % or more; and a precipitate with a particle size of less than 20 nm, wherein C* and C*satisfy specific conditions.

High strength steel sheet and manufacturing method therefor

A method of manufacturing a high-strength hot rolled steel sheet by hot rolling a steel having a chemical composition including, by mass %: C: more than 0.010% and not more than 0.06%, Si: not more than 0.3%, Mn: not more than 0.8%, P: not more than 0.03%, S: not more than 0.02%, Al: not more than 0.1%, N: not more than 0.01% and Ti: 0.05 to 0.10%, the balance including Fe and inevitable impurities, including: after the steel is heated to an austenite single phase region, the steel is finish rolled at a finishing delivery temperature of 860&#xb0; C. to 1050&#xb0; C., the steel sheet is cooled at an average cooling rate of not less than 30&#xb0; C./s in a temperature range of from a temperature after the completion of the finish rolling to 750&#xb0; C., and the steel sheet is coiled into a coil at a coiling temperature of 580&#xb0; C. to 700&#xb0; C.

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

This disclosure provides a predetermined composition, where a conversion value C* of total carbon contents in Ti, Nb and V precipitates whose grain sizes are less than 20 nm is 0.010 mass % to 0.100 mass %, Fe content in Fe precipitates is 0.03 mass % to 0.50 mass %, and an average grain size of ferrite grains whose grain sizes are top 5 % large in ferrite grain size distribution of rolling direction cross section is (4000/TS)&#x3bc;m or less, the TS indicating tensile strength in unit of MPa.

High-strength thin steel sheet and method for manufacturing the same

A steel sheet and a method for producing the same are disclosed. The steel sheet has a composition containing 0.015% to 0.05% C, less than 0.10% Si, 0.1% to 2.0% Mn, 0.20% or less P, 0.1% or less S, 0.01% to 0.10% Al, 0.005% or less N, and 0.06% to 0.5% Ti in percent by mass, C and Ti satisfying the inequality Ti*/C&#x2267;4, where Ti* (mass percent)=Ti&#x2212;3.4N and Ti, C, and N represent the content (mass percent) of each element. The steel sheet has a microstructure which contains a ferrite phase as a base, in which the average grain diameter of the ferrite phase is 7 &#x3bc;m or more, and in which the ratio of the rolling-direction average grain diameter to thickness-wise average grain diameter of the ferrite phase is 1.1 or more.

Steel sheet with excellent aging resistance property and method for producing the same

The high strength steel sheet has a chemical composition including 0.08% to 0.20% of C, 0.3% or less of Si, 0.1% to 3.0% of Mn, 0.10% or less of P, 0.030% or less of S, 0.10% or less of Al, 0.010% or less of N, 0.20% to 0.80% of V, and the remainder composed of Fe and incidental impurities on a percent by mass basis, and a microstructure which includes 95% or more of ferrite phase on an area percentage basis, in which fine precipitates are dispersed having a distribution in such a way that the number density of precipitates having a particle size of less than 10 nm is 1.0&#xd7;10/&#x3bc;mor more and the standard deviation of natural logarithm values of precipitate particle sizes with respect to precipitates having a particle size of less than 10 nm is 1.5 or less.

High strength steel sheet

A high-strength hot rolled steel sheets with excellent stretch flangeability has small variations in mechanical properties in individual coils. Variations in strength from place to place in a coil are decreased by minimally reducing the Si and Mn contents to suppress the occurrence of problems such as segregation. Further, the microstructure of the steel sheets is configured such that a ferrite phase represents an area ratio of not less than 95%, the ferrite crystal grains have an average grain size of not less than 1 &#x3bc;m, and the ferrite crystal grains contain TiC with an average particle size of not more than 7 nm dispersed in the crystal grains.

High-strength hot rolled steel sheet

A cold-rolled steel sheet includes, on a percent by mass basis: C: 0.0010% to 0.0030%, Si: 0.05% or less, Mn: 0.1% to 0.3%, P: 0.05% or less, S: 0.02% or less, Al: 0.02% to 0.10%, N: 0.005% or less, and Nb: 0.010% to 0.030% and the remainder composed of Fe and incidental impurities, wherein values in a rolling direction and a direction perpendicular to the rolling direction are within a range of 1.0 to 1.6, and a mean value Elof elongations in the rolling direction, a direction at 45&#xb0; with respect to the rolling direction, and the direction perpendicular to the rolling direction is 40% or more, where El=(El+2&#xd7;El+El)/4 and El: elongation in the rolling direction, El: elongation in the direction at 45&#xb0; with respect to the rolling direction, and El: elongation in the direction perpendicular to the rolling direction.

Cold-rolled steel sheet, method for manufacturing the same, and backlight chassis

A high strength steel sheet and a method for manufacturing the same has superior phosphatability properties and hot-dip galvannealed properties besides a tensile strength of 950 MPa or more and a high ductility, and also having a small variation in mechanical properties with the change in annealing conditions.

High strength steel sheet having superior ductility

Growing community of inventors

Tokyo, Japan

Taro Kizu