Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Voestalpine Stahl Gmbh

Junichiro Kinugasa

Fumio Yuse

Yoichi Mukai

Kouji Kasuya

Koji Noishiki

Wataru Urushihara

Muneaki Ikeda

Takeshi Ohwaki

Toshio Murakami

Hideo Hata

Michiharu Nakaya

Hiroshi Akamizu

Koichi Sugimoto

Andreas Pichler

Michitaka Tsunezawa

Shinji Kozuma

Akira Ibano

Atsuhiro Shiraki

Kosuke Shibata

Sandra Traint

Keisuke Nakata

Makoto Kawamori

A high-strength steel sheet with excellent delayed fracture resistance, having a tensile strength of 1700 MPa or larger, including a predetermined component composition, having a martensite structure whose ratio accounts for 95 area % or more of the entire metallographic structure, and having a transition metal carbide whose ratio accounts for 0.8 volume % or more of the entire metallographic structure.

High-strength steel sheet having excellent delayed fracture resistance

Disclosed is a high strength steel sheet having excellent hydrogen embrittlement resistance. The steel sheet has a tensile strength of 1180 MPa or more, and satisfies the following conditions: with respect to an entire metallographic structure thereof, bainite, bainitic ferrite and tempered martensite account for 85 area % or more in total; retained austenite accounts for 1 area % or more; and fresh martensite accounts for 5 area % or less (including 0 area %).

High strength steel sheet having excellent hydrogen embrittlement resistance

Disclosed is a high-strength cold-rolled steel sheet having improved stretch-flange formability and excellent hydrogen embrittlement resistance. In addition to Fe, C, Si, Mn, P, S, N, and Al, the steel sheet contains V or at least one element of Nb, Ti and Zr. The contents of the at least one element of Nb, Ti and Zr, if present, satisfy the expression of [% C]&#x2212;[% Nb]/92.9&#xd7;12&#x2212;[% Ti]/47.9&#xd7;12&#x2212;[% Zr]/91.2&#xd7;12&#x3e;0.03. The steel sheet has an area ratio of tempered martensite of 50% or more with ferrite as the remainder. The number of precipitates having a circle-equivalent diameter of 1 to 10 nm is 20 particles or more per 1 &#x3bc;mof the tempered martensite. The number of precipitates containing V or the at least one element of Nb, Ti and Zr and having a circle-equivalent diameter of 20 nm or more is 10 particles or less per 1 &#x3bc;mof the tempered martensite.

Cold-rolled steel sheet

The present invention is the thin steel sheet containing C, Si, Mn, P, S, Al, Mo, Ti, B, and N wherein a value Z calculated by the equation described below is 2.0-6.0, an area ratio against all the structure is 1% or above for retained austenite and 80% or above for total of bainitic ferrite and martensite, a mean axis ratio of the retained austenite crystal grain is 5 or above, and tensile strength is 980 MPa or above whereValue Z=9&#xd7;[C]+[Mn]+3&#xd7;[Mo]+490&#xd7;[B]+7&#xd7;[Mo]/{100&#xd7;([B]+0.001),andthe thin steel sheet has 980 MPa or above tensile strength and enhanced hydrogen embrittlement resistance properties.

High-strength thin steel sheet

An aluminum alloy material having an excellent sea water corrosion resistance comprises an aluminum alloy substrate whose ten-points average surface roughness Rz, which is the average of five greatest peak-to-valley separations on the surface, is controlled at 0.3 &#x3bc;m or over, an organic phosphonic primer film formed on a surface of the aluminum alloy substrate, and a fluorine resin paint film formed on the primer film and having a dry average thickness of 1 to 100 &#x3bc;m. A plate heat exchanger having an excellent sea water corrosion resistance is also provided wherein the aluminum alloy material is used as a heat transfer unit using sea water as cooling water.

Aluminum alloy material having an excellent sea water corrosion resistance and plate heat exchanger

Disclosed are an aluminum alloy material and a plate heat exchanger using the aluminum alloy material, both of which have superior corrosion resistance. Specifically, the aluminum alloy material includes an aluminum alloy base material having an anodic oxide layer with an average thickness of 1 to 20 &#x3bc;m as its surface layer, an organic phosphonic acid primer coating arranged on the surface of the aluminum alloy base material, and a fluorocarbon resin coating arranged on the surface of the organic phosphonic acid primer coating and having an average thickness of 1 to 100 &#x3bc;m after drying.

Aluminum alloy material and plate heat exchanger with superior corrosion resistance

The invention relates to an ultrahigh-strength thin steel sheet excellent in the hydrogen embrittlement resistance, the steel sheet including, by weight %, 0.10 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, 0.15% or less of P, 0.02% or less of S, 1.5% or less of Al, 0.003 to 2.0% of Cr, and a balance including iron and inevitable impurities; in which grains of residual austenite have an average axis ratio (major axis/minor axis) of 5 or more, the grains of the residual austenite have an average minor axis length of 1 &#x3bc;m or less, and the grains of the residual austenite have a nearest-neighbor distance between the grains of 1 &#x3bc;m or less.

Ultrahigh-strength thin steel sheet

Growing community of inventors

Kobe, Japan

Junichiro Kinugasa