Kobe Steel, Ltd.

Masao Kinefuchi

Katsushi Matsumoto

Mikako Takeda

Tomokazu Nakagawa

Kenichi Watanabe

Toshiki Ueda

Mamoru Nagao

Shimpei Kimura

Fumihiro Koshigoe

Takunori Yamaguchi

Eiichi Tamura

Yasuo Murai

Mie Tachibana

Toshio Murakami

Reiichi Suzuki

Hideo Hata

Takahiro Izumi

Koji Fukumoto

Hiroyuki Takeda

Noritaka Eguchi

Ryu Kasai

This high-strength hot-rolled steel plate contains specific amounts of C, Si, Mn, Al, V and also Ti and/or Nb so as to fulfill C&#x2212;12(V/51+Ti/48+Nb/93)&#x3e;0.03, and the rest consists of iron and unavoidable impurities. Ferrite is the main microstructure, the remaining microstructure is one or more selected from the group consisting of bainite, martensite and retained austenite, wherein the average particle diameter of precipitated carbides (the total content of V, Ti and Nb is 0.02% or greater) in the ferrite is less than 6 nm.

High-strength hot-rolled steel sheet

A fillet weld joint of steel formed by arc welding, wherein a martensitic transformation starting temperature (Ms point) of a weld metal is 400&#xb0; C. or above and 550&#xb0; C. or below, a value obtained by dividing a toe radius &#x3c1; of a toe part of welding by a sheet thickness t of a base metal (&#x3c1;/t) is 0.25 or above, an expression Ms(&#xb0; C.)&#x2266;375&#xd7;[&#x3c1;/t]+320 is satisfied, and a crack defect does not exist in the fillet weld joint.

Fillet weld joint and method for gas shielded arc welding

In the bonding of an aluminum alloy material () to a steel material () by TIG welding, a tungsten electrode () which has a tip having a diagonally cut tip face () and asymmetrical to the electrode center axis () is used. The tungsten electrode () is oriented toward the welding line from the upper side of the aluminum alloy material () in such a manner that the tip face side of the tungsten electrode () faces the aluminum alloy material () side and the tip () of the tip face () faces the steel material () side. In this manner, an arc () from the tip () is directed to the steel material () side.

Method for bonding dissimilar metals to each other

There are provided an aluminum-alloy clad sheet and a clad sheet subjected to heating equivalent to brazing, which each have a high strength and an excellent erosion resistance and thus allow a reduction in thickness of a clad sheet subjected to heating equivalent to brazing such as an aluminum alloy radiator tube, and/or of a clad sheet such as an aluminum-alloy brazing sheet. An aluminum-alloy clad sheet or a clad sheet subjected to heating equivalent to brazing includes at least a core aluminum alloy sheet and an aluminum-alloy sacrificial anti-corrosive material cladded with each other, and is to be formed into a heat exchanger by brazing. The core aluminum alloy sheet includes a specified 3000 series composition. Furthermore, the strength and the erosion resistance of the core aluminum alloy sheet are improved through control of grain size distribution of precipitates having a size in a specified level in the core aluminum alloy sheet, or control of the average number density and the composition of dispersed particles therein.

Aluminum-alloy clad sheet

A bumper beam having increased bending strength achieved with a minimum increase in the weight of the bumper beam. The bumper beam () is mounted to the front of a vehicle, extends along a reference line (W), and is provided with a beam body () and a reinforcing plate (). In at least one cross section perpendicular to the reference line (W), the reinforcing plate () extends linearly and the beam body () includes a pair of protrusions () protruding, while surrounding an inner space, from the reinforcing plate () in a direction intersecting the reinforcing plate (). If the Young's modulus and the density of the beam body () are Eand &#x3c1;, respectively, and the Young's modulus and the density of the reinforcing plate () are Eand &#x3c1;, respectively, the expression (Et/&#x3c1;)&#x3c;(E/&#x3c1;) is satisfied.

Bumper beam

A bumper structure which as a whole has a reduced weight and which has sufficient buckling strength. A bumper structure has a box-like outer shape constituted of a front flange (), a rear flange (), an upper web (), and a lower web () which consist of a steel material. An intermediate web () consisting of a material other than the steel material is disposed between the upper web () and the lower web (). If the Young's modulus of the steel material is E, the density of the steel material is &#x3c1;, the Young's modulus of the material which forms the intermediate web () is E, and the density of the material which forms the intermediate web () is &#x3c1;, the bumper structure satisfies E/&#x3c1;&#x3c;E/&#x3c1;.

Bumper structure

Provided is a multi-layered sheet which has undergone heating corresponding to brazing, such as an aluminum-alloy radiator tube, or a multi-layered sheet such as an aluminum-alloy brazing sheet. The multi-layered sheet can have a reduced thickness and has excellent fatigue properties. The multi-layered sheet of aluminum alloys comprises a core layer () which has been clad at least with a sacrificial layer (). This multi-layered sheet is a multi-layered sheet to be subjected to brazing or welding to produce a heat exchanger or is a multi-layered sheet which has undergone heating corresponding to brazing. The core layer () comprises a specific 3000-series composition. In this core layer (), the average density in number of dispersed particles having a specific size has been regulated. As a result, fatigue properties, which govern cracking, can be highly improved.

Multi-layered sheet of aluminum alloys

A joined body of dissimilar metals which is produced by joining a steel material and an aluminum alloy material, wherein the steel material to be joined has a specific composition and is specified in the compositions of outer surface oxide layer and inner oxide layer and the aluminum alloy material to be joined is an Al&#x2014;Mg-base or Al&#x2014;Zn&#x2014;Mg-base aluminum alloy having a specific composition. In the joined body of dissimilar metals, a content of Fe at a joint interface on the aluminum alloy material side is regulated, and a reaction layer of Fe and Al is formed at the joint interface of the joined body of dissimilar metals. The joined body of dissimilar metals exhibits high joint strength.

Steel material for dissimilar metal joining, joined body of dissimilar metals and process for joining dissimilar metal materials

A joined body of dissimilar metals which is produced by joining a steel material and an aluminum alloy material, wherein the steel material to be joined has a specific composition and is specified in the compositions of outer surface oxide layer and inner oxide layer and the aluminum alloy material to be joined is an Al&#x2014;Mg&#x2014;Si-base aluminum alloy having a specific composition. In the joined body of dissimilar metals, a content of Fe at a joint interface on the aluminum alloy material side is regulated, and a reaction layer of Fe and Al is formed at the joint interface of the joined body of dissimilar metals. The joined body of dissimilar metals exhibits high joint strength.

Disclosed herein is an aluminum alloy clad sheet for a heat exchanger including a core layer, a sacrificial layer formed on one surface of the core layer, and a filler layer including an Al&#x2014;Si based alloy formed on the other surface of the core layer. The core layer includes a predetermined amount of Si, Cu, Mn, Ti, and Mg, the remainder including Al and inevitable impurities, and the sacrificial layer includes a predetermined amount of Si, Mn, and Zn, the remainder including Al and inevitable impurities. The core layer has a crystal grain size after the brazing heat treatment at 595&#xb0; C. for 3 minutes of at least 50 &#x3bc;m and less than 300 &#x3bc;m. The filler layer and the sacrificial layer are defined for their thickness, and the number of intermetallic compounds in the core layer is also defined to a predetermined range. By such constitution, the aluminum alloy clad sheet has improved fatigue life and post-braze strength, high corrosion resistance, and excellent erosion resistance and brazeability.

Aluminum alloy clad sheet for a heat exchanger and its production method

Disclosed are: a dissimilar material weld joint being formed by joining an iron type material and an aluminum type material and having not only a high strength but also an excellent ductility; and a weld joining method allowing such a joint to be stably produced. A dissimilar material weld jointformed by joining an iron type materialand an aluminum type material, wherein: voidsare formed beforehand on the side of said iron type materialat a predetermined interval along a weld line; both said iron type and aluminum type materials are weld joined so that said voidsare filled with molten aluminum; and the minimum value of the ratio (L-Al)/(L-Fe) of the length (L-Al) of an aluminum type welding materialwith which said voidsare filled to the length (L-Fe) of said iron type materialadjacent to said voidsfilled with said aluminum type welding materialalong said weld lineon the section containing said weld lineis in the range from 0.5 to 7, both the lengths (L-Al) and (L-Fe) being the lengths per 100 mm in length of the weld lineformed after welding.

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Kobe, Japan

Masao Kinefuchi