Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Shunji Hiwatashi

Naoki Yoshinaga

Manabu Takahashi

Toshiyuki Niwa

Yasuharu Sakuma

Kunio Hayashi

Akihiro Uenishi

Tohru Yoshida

Eisaku Sakurada

Shigeru Yonemura

Natsuko Sugiura

Akihiro Miyasaka

Takehide Senuma

Koji Hanya

Ryoichi Kanno

Atsushi Itami

Nobuyoshi Uno

Koichi Sato

Noriyuki Suzuki

Shinichi Suzuki

Kaoru Kawasaki

Akira Shirai

Yasuharu Tanaka

Hiroshi Yoshida

Satoshi Hirose

Yukihisa Kuriyama

Kazuo Koyama

Takashi Ariga

Seiichi Daimaru

Matsuo Usuda

Shin Toyokawa

Satoru Okayama

Yusuke Kamada

An analyzing apparatus generates first displacement distribution data indicating a displacement distribution of a member caused by springback based on finite element model data, material physical property data, and stress distribution data; generates second displacement distribution data indicating an amount of displacement of the member in each of a plurality of, for example, all, natural vibration deformation modes based on the finite element model data and the material physical property data; obtains a degree of coincidence between the first displacement distribution data and each of the second displacement distribution data, and selects one or more natural vibration deformation modes based on the degree of coincidence, to determine a modified shape in which natural vibrations are increased, thereby bringing the member closer to a target shape.

Analyzing apparatus, analyzing method, and computer program

A hot-rolled steel sheet including, in terms of % by mass, 0.030% to 0.120% of C, 1.20% or less of Si, 1.00% to 3.00% of Mn, 0.01% to 0.70% of Al, 0.05% to 0.20% of Ti, 0.01% to 0.10% of Nb, 0.020% or less of P, 0.010% or less of S, and 0.005% or less of N, and a balance consisting of Fe and impurities, in which 0.106&#x2265;(C %-Ti %*12/48-Nb %*12/93)&#x2265;0.012 is satisfied; a pole density of {112}(110) at a position of &#xbc; plate thickness is 5.7 or less; an aspect ratio (long axis/short axis) of prior austenite grains is 5.3 or less; a density of (Ti, Nb)C precipitates having a size of 20 nm or less is 10pieces/mmor more; a yield ratio YR, which is the ratio of a tensile strength to a yield stress, is 0.80 or more; and a tensile strength is 590 MPa or more.

Hot-rolled steel sheet and manufacturing method for same

An analyzing method of a spot welded portion, includes: acquiring bar elements as the spot welded portion; extracting other bar elements existing at a periphery of a target bar element which is targeted among the acquired bar elements; determining whether or not there is a bar element which shares the same end point with the target bar element among the extracted bar elements; determining that the target bar element and the bar element which shares the same end point with the target bar element are a three-layer spot welded portion when it is determined that there is the bar element which shares the same end point with the target bar element; and determining whether or not there is a bar element whose distance between elements with the target bar element is within a predetermined distance among the extracted bar elements when it is determined that there is not the bar element which shares the same end point with the target bar element, and determining that the target bar element and the extracted bar element are not the three-layer spot welded portion when it is determined that there is not the bar element within the predetermined distance.

Analyzing method of spot welded portion, analyzing program of spot welded portion, recording medium and analyzing apparatus of spot welded portion

A hot-rolled steel sheet for nitriding or a cold-rolled steel sheet for nitriding, in which a dislocation density within 50 &#x3bc;m in the sheet thickness direction from the surface is not less than 2.0 times nor more than 10.0 times as compared to a dislocation density at the position of &#xbc; in the sheet thickness direction; and a method of manufacturing the same. The manufacturing method comprises, on a hot-rolled steel sheet or a cold-rolled steel sheet, performing pickling, and then performing skin pass rolling under the condition that a reduction ratio is 0.5 to 5.0% and FIT, defined as a ratio of a line load F (kg/mm) of a rolling mill load divided by a sheet width of the steel sheet and a load T (kg/mm) per unit area to be applied in the longitudinal direction of the steel sheet, is 8000 or more.

Hot-rolled steel sheet for nitriding, cold-rolled steel sheet for nitriding excellent in fatigue strength, manufacturing method thereof, and automobile part excellent in fatigue strength using the same

A method of identification of a cause of occurrence of springback comprising a press forming analysis step of numerically analyzing forming conditions of press forming to obtain forming data of a press formed part, a processing step of processing at least one of a physical property value and physical property quantity data of part of the regions of said press formed part among forming data of said press formed part, and a springback value calculation step of calculating a springback value based on the results of said processing.

Method of identification of cause and/or location of cause of occurrence of springback

According to exemplary embodiments of the present invention, using a fracture limit stress line obtained by converting a hole expansion ratio into a stress as a criterion for a fracture, the risk of fracture in a material can be evaluated quantitatively by comparing the relationship between data obtained from a numerical analysis using a finite element method and the fracture limit stress line. Thus, when determining a fracture limit in a stretch flange portion in a thin plate in a process including one or more deformation path variations, it is possible to obtain the fracture limit curve easily and efficiently and predict the fracture with high accuracy, and the risk of fracture upon press forming or crash can be evaluated.

Fracture prediction method, device, a program arrangement and computer-accessible medium therefor

In an embodiment of a steel sheet having high Young's modulus, the steel can include in terms of mass %, e.g., C: 0.0005 to 0.30%, Si: 2.3% or less, Mn: 2.7 to 5.0%, P: 0.15% or less, 0.015% or less, Mo: 0.15 to 1.5%, B: 0.0006 to 0.01%, and Al: 0.15% or less, with the remainder being Fe and unavoidable impurities. One or both of {110}&#x3c;223&#x3e; pole density and {110}&#x3c;111&#x3e; pole density in the &#x215b; sheet thickness layer can be 10 or more, and a Young's modulus in a rolling direction can be more than 230 GPa. Other embodiments can include, e.g., Mn: 0.1 to 5.0%, N: 0.01% or less, and one or more of Mo: 0.005 to 1.5%, Nb: 0.005 to 0.20%, Ti: at least 48/14&#xd7;N (mass %) and 0.2% or less, and B: 0.0001 to 0.01%, at a total content of 0.015 to 1.91 mass %.

Steel sheet having high young's modulus, hot-dip galvanized steel sheet using the same, alloyed hot-dip galvanized steel sheet, steel pipe having high young's modulus, and methods for manufacturing the same

High yield ratio high-strength hot rolled thin steel sheet superior in weldability and ductility comprising, by mass %, C: over 0.030 to less than 0.10%, Si: 0.30 to 0.80%, Mn: 1.7 to 3.2%, P: 0.001 to 0.02%, S: 0.0001 to 0.006%, Al: 0.060% or less, N: 0.0001 to 0.0070%, containing further Ti: 0.01 to 0.055%, Nb: 0.012 to 0.055%, Mo: 0.07 to 0.55%, B: 0.0005 to 0.0040%, and simultaneously satisfying 1.1&#x2266;14&#xd7;Ti(%)+20&#xd7;Nb(%)+3&#xd7;Mo(%)+300&#xd7;B(%)&#x2266;3.7, the balance comprised of iron and unavoidable impurities, and having a yield ratio of 0.64 to less than 0.92, a TS&#xd7;Elof 3320 or more, an YR&#xd7;TS&#xd7;Elof 2320 or more, and a maximum tensile strength (TS) of 780 MPa or more.

High yield ratio and high-strength thin steel sheet superior in weldability and ductility, high-yield ratio high-strength hot-dip galvanized thin steel sheet, high-yield ratio high-strength hot-dip galvannealed thin steel sheet, and methods of production of same

A fracture determination method for determining a fracture of a metal structure includes, when a fracture determination target portion has returned from a plastic state to an elastic state, given that a stress when the portion returned to the elastic state is (x, y)=(&#x3c3;) (maximum principal stress: &#x3c3;, minimum principal stress: &#x3c3;) on a (x, y) coordinate plane, performing fracture determination of the fracture determination target portion using a re-yield stress R determined by the intersection between a straight line satisfying a relation y=(&#x3c3;)x and an yield curve obtained from the plastic state of the fracture determination target portion. Fracture determination can be performed with high accuracy even when the fracture determination target portion has returned from a plastic state to an elastic state.

Fracture determination method, fracture determination apparatus, program, and computer readable recording medium

High yield ratio high-strength thin steel sheet superior in weldability and ductility characterized by: being comprised of steel containing, by mass %, C: over 0.030 to less than 0.10%, Si: 0.30 to 0.80%, Mn: 1.7 to 3.2%, P: 0.001 to 0.02%, S: 0.0001 to 0.006%, Al: 0.060% or less, N: 0.0001 to 0.0070%, containing further Ti: 0.01 to 0.055%, Nb: 0.012 to 0.055%, Mo: 0.07 to 0.55%, B: 0.0005 to 0.0040%, and simultaneously satisfying 1.1 &#x2266;14&#xd7;Ti(%)+20&#xd7;Nb(%)+3&#xd7;Mo(%)+300&#xd7;B(%)&#x2266;3.7, the balance comprised or iron and unavoidable impurities, and having a yield ratio of 0.64 to less than 0.92, a TS&#xd7;E1of 3320 or more, an YR&#xd7;TS&#xd7;ELof 2320 or more, and a maximum tensile strength (TS) of 780 MPa or more.

High-yield-ratio and high-strength thin steel sheet superior in weldability and ductility, high-yield-ratio high-strength hot-dip galvanized thin steel sheet, high-yield ratio high-strength hot-dip galvannealed thin steel sheet, and methods of production of same

One aspect of the steel sheet having high Young's modulus includes in terms of mass %, C: 0.0005 to 0.30%, Si: 2.5% or less, Mn: 2.7 to 5.0%, P: 0.15% or less, S: 0.015% or less, Mo: 0.15 to 1.5%, B: 0.0006 to 0.01%, and Al: 0.15% or less, with the remainder being Fe and unavoidable impurities, wherein one or both of {110}&#x3c;223&#x3e; pole density and {110}&#x3c;111&#x3e; pole density in the &#x215b; sheet thickness layer is 10 or more, and a Young's modulus in a rolling direction is more than 230 GPa. Another aspect of the steel sheet having high Young's modulus includes, in terms of mass %, C: 0.0005 to 0.30%, Si: 2.5% or less, Mn: 0.1 to 5.0%, P: 0.15% or less, S: 0.015% or less, Al: 0.15% or less, N: 0.01% or less, and further comprises one or two or more of Mo: 0.005 to 1.5%, Nb: 0.005 to 0.20%, Ti: at least 48/14&#xd7;N (mass %) and 0.2% or less, and B: 0.0001 to 0.01%, at a total content of 0.015 to 1.91 mass %, with the remainder being Fe and unavoidable impurities, wherein the {110}&#x3c;223&#x3e; pole density and/or the {110}&#x3c;111&#x3e; pole density in the &#x215b; sheet thickness layer is 10 or more, and a Young's modulus in a rolling direction is more than 230 GPa.

Steel sheet having high young'S modulus, hot-dip galvanized steel sheet using the same, alloyed hot-dip galvanized steel sheet, steel pipe having high young'S modulus and methods for manufacturing the same

High-strength steel sheet suitable for deep drawing and process for

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Tokyo, Japan

Shunji Hiwatashi