Kobe Steel, Ltd.

Nisshin Steel Co., Ltd.

Tetsu Iwase

Seiji Sasabe

Shunichi Hashimoto

Yoshihaya Imamura

Yasunori Hattori

Tadaaki Miono

Jun Katoh

Hiroyuki Takeda

Atsushi Andoh

Fumihiro Sato

Kensuke Tsubota

Mitsuo Hino

Provided is a different materials panel structure having reduced occurrence of displacement or warping of a joining section and having excellent external appearance of an outer panel (). The different materials panel structure has: an outer panel comprising a first metal material; an inner panel () arranged on the lower surface side of the outer panel and comprising a second metal material having a higher fusion point than the first metal material; and a rivet () comprising the same material as the second metal material and comprising a head section and a shaft section. An outer panel comprises a hemmed section formed by folding a rim section and which supports the inner panel via an adhesive layer (). The head section of the rivet remains on the outer panel surface. The shaft section of the rivet penetrates from the lower surface side of the hemmed section of the outer panel towards the inner panel. A tip of the shaft section is spot-welded to the inner panel and a protruding section () is provided in the inner panel at a position corresponding to the rivet and protruding in the axial direction of the rivet. A heat insulation section () comprising the adhesive layer or the adhesive layer and a gap is formed between the protruding section after welding and the outer panel.

Different materials panel structure

A steel/aluminum welded structure comprises a hot-dip Al-coated steel sheetspot welded with an aluminum or aluminum alloy sheet. The steel sheetis coated with a coating layercontaining, by mass, 3-12% of Si and 0.5-5% of Fe. An area ratio of an Al&#x2014;Fe binary alloy layer, formed at the joint boundary, is controlled to 90% or less. An unalloyed regionexists between an Al&#x2014;Fe&#x2014;Si ternary alloy layerat an interface of a steel substratewith the coating layerinterface and the Al&#x2014;Fe binary alloy layer at the joint boundary. A steel substratepreferably contains 0.002-0.020% of N for formation of a N-enriched surface layer in contact with the coating layer. The N-enriched layer impedes propagation of the brittle Al&#x2014;Fe binary alloy layer to the whole of the joint boundary and raises joint strength of the steel/aluminum welded structure.

Steel/aluminum welded structure

A joined part of an aluminum-coated steel sheet and an aluminum sheet is composed of an intermetallic compound layer which exists in a region in which a part of a coated layer exists before the joining and an aluminum melted and solidified part which also exists on the side of the aluminum sheet to enclose the intermetallic compound layer. The atoms existing on the surface of the aluminum melted and solidified part are intermetallic-bonded with atoms which exist on the surface of the steel sheet except in the region in which the intermetallic compound layer exists seen in the plan view. Further, the area of the intermetallic compound layer is limited to 60% or less of the total area of the joined part at the interface between the aluminum-coated steel sheet and the aluminum sheet. Thus, the area of the aluminum melted and solidified part exceeds 40% of the total area of the joined part. The strong joining having a high fracture energy can be provided at a high efficiency.

Weldment of different materials and resistance spot welding method

Growing community of inventors

Fujisawa, Japan

Tetsu Iwase