Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho (kobe Steel, Ltd.)

Kabushiki Kaisha Kobe Seiko Sho

Koichi Makii

Shushi Ikeda

Hiroshi Akamizu

Shunichi Hashimoto

Yoichi Mukai

Nobuhiko Ibaraki

Takaaki Minamida

Koichi Sugimoto

Takahiro Kashima

Yosuke Shindo

Masahiro Nomura

Koh-ichi Sugimoto

Koji Inoue

Kenichi Inoue

Kenji Saito

Hiroshi Yaguchi

Yoshihiro Yokota

Mamoru Nagao

Kyoji Zaitsu

Hiroyuki Takeda

Kouki Ikeda

Masato Kaiso

Atsushi Inada

Kenji Ochiai

Masafumi Shimizu

Takayuki Yamamoto

Ikurou Hashimoto

Kenji Saitou

Sakae Wada

This heat sink has bonded on one surface a member to be bonded, and has a cooling member in contact with the other surface. The heat sink is provided with a metal plate having a thermal expansion coefficient larger than that of the member to be bonded, and the metal plate is provided with a center portion where the member to be bonded is bonded, and a plurality of linear peripheral slits formed in a whirl-like radial manner such that the linear peripheral slits surround the center portion.

Heat sink and method for manufacturing heat sink

A dual phase steel sheet with good bake-hardening properties is provided. The steel sheet is characterized in containing (in terms of percent by mass) C: no less than 0.06% and less than 0.25%; Si+Al: 0.5 to 3%; Mn: 0.5 to 3%; P: no more than 0.15%; and S: no more than 0.02%; and also meeting the following condition (in terms of space factor) that retained austenite is at least 3%, bainite is at least 30%, and ferrite is no more than 50%, and further characterized in differing in stress larger than 50 MPa before and after application of 2% pre-strain and ensuing heat treatment for paint baking at 170&#xb0; C. for 20 minutes. The steel sheet has well-balanced strength and workability, exhibits good bake-hardening properties at the time of paint baking, and offers good resistance to natural aging.

Dual phase steel sheet with good bake-hardening properties

A high-strength cold rolled steel sheet contains: 0.10 to 0.28% of C, 1.0 to 2.0% of Si, 1.0 to 3.0% of Mn, and 0.03 to 0.10% of Nb in terms of % by mass, Al is controlled to 0.5 or less, P is controlled to 0.15% or less, and S is controlled to 0.02% or less, and residual austenite accounts for 5 to 20%, bainitic ferrite accounts for 50% or more, and polygonal ferrite accounts for 30% or less (containing 0%), of the entire structure, and a mean number of residual austenite blocks is 20 or more as determined when the random area (15 &#x3bc;m&#xd7;15 &#x3bc;m) is observed by EBSP (electron back scatter diffraction pattern).

High-strength cold rolled steel sheet having excellent formability, and plated steel sheet

A high-strength forged part is disclosed which comprises a base phase structure, comprising 30% or more of ferrite in terms of a space factor, and a second phase structure, comprising bainite and/or martensite, and retained austenite having an average gain diameter of 5 &#x3bc;m or less and a content represented by 50X[C]&#x3c;[V]&#x3c;150x[C], wherein [V] represents a space factor of the retained austenite (&#x3b3;R) and [C] represents the mass % of C in the forged part. Furthermore, a high-strength forged part is disclosed which comprises a base phase structure, comprising 50% or more of tempered bainite or tempered martensite in terms of a space factor, and a second phase structure, comprising martensite and 3% to 30% retained austenite in terms of a space factor, wherein the portion of the retained austenite and martensite having an aspect ratio of 2 or less is 25% or less in terms of a space factor.

Method for producing high-strength forged parts having high reduction of area

To provide a high strength and low yield ratio cold rolled steel sheet having high elongation property and high flange drawing property, or a plated steel sheet made by plating the same. The high strength and low yield ratio cold rolled steel sheet or the plated steel sheet made by plating the same has such a constitution as 0.10 to 0.25% of C, 1.0 to 2.0% of Si and 1.5 to 3.0% of Mn, are contained in terms of weight percentage, while other elements are controlled such as Al within 0.2%, P within 0.15% and S within 0.02%, with residual austenite occupying at least 5%, bainitic ferrite occupying at least 60% (preferably 80% or more), and polygonal ferrite within 20% (containing 0%), so that a tensile strength is 980 MPa or higher, while an elongation (El in %), a flange drawing property (&#x3bb;in %), a tensile strength (TS in MPa) and a yield strength (YP in MPa) satisfy the following inequality (1): [(El &#xd7;&#x3bb;&#xd7;TS)/YP]&#x2267;645.

High strength and low yield ratio cold rolled steel sheet and method of manufacturing the same

A high-strength forged part is disclosed which comprises a base phase structure, comprising 30% or more of ferrite in terms of a space factor, and a second phase structure, comprising bainite and/or martensite, and retained austenite having an average grain diameter of 5 &#x3bc;m or less and a content represented by 50&#xd7;[C]&#x3c;[V]&#x3c;150&#xd7;[C], wherein [V] represents a space factor of the retained austenite (&#x3b3;R) and [C] represents the mass % of C in the forged part. Furthermore, a high-strength forged part is disclosed which comprises a base phase structure, comprising 50% or more of tempered bainite or tempered martensite in terms of a space factor, and a second phase structure, comprising martensite and 3% to 30% retained austenite in terms of a space factor, wherein the portion of the retained austenite and martensite having an aspect ratio of 2 or less is 25% or less in terms of a space factor.

High-strength forged parts having high reduction of area and method for producing same

A high-strength steel sheet comprises carbon: 0.06 to 0.25 mass %, Si: 0.5 to 3.5 mass % and Mn: 0.7 to 4 mass %. Its mother structure is ferrite, its second phase structure comprises martensite and the residual austenite and the second phase structure measured by image analysis has an area fraction of 25% or less based on the total structure. The steel sheet satisfies the following requirements (1) to (3): (1) the volume fraction (Vt&#x3b3;hd R) of the residual austenite is 5% or more; (2) the ratio (SF&#x3b3;/Vt&#x3b3;) of the area fraction (SF&#x3b3;) of the residual austenite within ferrite to Vt&#x3b3;is 0.65 or more; and (3) the ratio [&#x3b1;2/(&#x3b1;1+&#x3b3;)] of the space factor (&#x3b1;2) of martensite to the second phase structure (&#x3b1;1+&#x3b3;) is 0.25 to 0.60. The steel sheet has excellent balance between strength and local elongation, and a low yield ratio.

High-strength steel sheet having excellent workability and production process therefor

A hot-dip galvanized steel sheet composed of a basis steel sheet containing Si in an amount of 0.05-2.5 mass % and Mn in an amount of 0.2-3 mass % and a hot-dip galvanized zinc layer formed on the surface thereof, wherein said hot-dip galvanized zinc layer is formed in such a way that there is an Si&mdash;Mn enriched phase which is found, by observation under a scanning electron microscope or a transmission electron microscope, in the vicinity of the interface in a region no shorter than 50 &mgr;m in the cross section perpendicular to the interface between the basis steel sheet and the hot-dip galvanized zinc layer, said Si&mdash;Mn enriched phase containing more than twice as much Si and/or Mn as the basis steel sheet and extending over a length no more than 80% of the length of the interface observed. This hot-dip galvanized steel sheet is free of bare spots even in the case where the basis steel sheet contains Si and Mn in a comparatively large amount and hence is liable to suffering bare spots.

Hot-dip galvanized steel sheet

High-carbon steel wire superior in resistance to longitudinal cracking, steel product for the same, and process for production of the same

A P- and Ti-added galvannealed steel sheet superior in ductility, and a process for production thereof. It is made of a cold-rolled steel sheet and has alloyed hot-dip galvanizing on the surface thereof, said cold-rolled steel sheet having the chemical composition (in terms of wt %) of C: less than 0.010%, Si: no more than 0.5%, Mn: 1.0&tilde;3.0%, P: no more than 0.20%, S: no more than 0.01%, Al: 0.005&tilde;0.10%, N: no more than 0.0050%, Ti/48&minus;(C/12&plus;N/14&plus;S/32): 0.0003&tilde;0.0018 with the remainder being chiefly Fe, and said cold-rolled steel sheet being characterized by &rgr;1&lE;10,and &rgr;2&lE;5&times;10,, where &rgr;1 is the number of precipitates whose particle diameter (D) is in the range of 10 nm&lE;D<100 nm and &rgr;2 is the number of precipitates whose particle diameter (D) is in the range of 100 nm&lE;D.

Galvanized steel sheet superior in ductility and process for production thereof

A hot-dip galvanized steel sheet which is produced from a cold-rolled steel sheet, as a base steel sheet, consisting essentially of C: 0.010-0.06 wt %, Si: no more than 0.5 wt %, Mn: no less than 0.5 wt % and less than 2.0 wt %, P: no more than 0.20 wt %, S: no more than 0.01 wt %, Al: 0.005-0.10 wt %, N: no more than 0.005 wt %, Cr: no more than 1.0 wt %, Mn&plus;1.3Cr: 1.9-2.3 wt %, Fe: remainder, and having a structure composed of ferrite and a second phase containing martensite, said second phase in the structure accounting for no more than 20% in terms of area and martensite in the second phase accounting for no less than 50%, and which has a zinc-plated layer formed on the surface thereof by hot-dip galvanizing or hot-dip galvannealing. A process for production of said hot-dip galvanized steel sheet. This steel sheet has a composite structure containing martensite and yet it has a low strength (no higher than 500 MPa) and also has good strength-ductility balance.

Hot-dip galvanized steel sheet and process for production thereof

A steel wire is composed mainly of fine pearlite and/or coarse pearlite, where the lamellar cementite in the pearlite is amorphous or amorphous-like. Alternatively, the wire may be composed mainly of bainite, where the cementite in the bainite is amorphous or amorphous-like. To manufacture the steel wire, a starting steel product is subjected repeatedly to patenting and cold drawing, and then subjected to final drawing at a true strain of 2.0 or above while cooling. The steel wire is higher in strength and toughness than wire whose lamellar cementite consists of nano crystals. The steel wire does not suffer any delamination when subjected to torsion.

High strength and high toughness steel wires and method for making the

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Kobe, Japan

Koichi Makii