# US 11,897,053 B2 · Joining structure

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- Number: US 11,897,053 B2
- Document ID: US11897053B2
- Status: Granted
- Kind: B2
- Application number: 17/076,839
- Filed: 2020-10-22
- Published: 2021-04-29
- Granted: 2024-02-13
- Earliest claimed: 2019-10-23
- Assignees: Denso Corporation
- Applicants: Denso Corporation
- Inventors: Yuuya Takahashi; Syusuke Ootsuki; Tomohiro Shimizu; Sumera Shimizu
- Web page: https://patentgrep.com/patent/US11897053B2

## CPC

- B23K 26/244: Overlap seam welding
- B23K 26/08: Devices involving relative movement between laser beam and workpiece
- B23K 26/21: by welding
- B23K 26/26: of rectilinear seams
- B23K 26/32: taking account of the properties of the material involved
- B23K 2101/18: Sheet panels
- B23K 2103/05: {Stainless steel}
- B23K 2103/10: Aluminium or alloys thereof
- B23K 2103/14: Titanium or alloys thereof
- B23K 2103/26: {Alloys of Nickel and Cobalt and Chromium}
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM

## Abstract

Provided is a joining structure capable of simplifying the manufacturing process and having high corrosion resistance. A joining structure has a welded part for connecting joined members made of a metal that forms a passive film. An outermost surface portion of the welded part has a pitting potential. The welded part may include a welded part main body formed inside and a surface-modified layer formed in contact with the welded part main body, and the surface-modified layer may include the outermost surface portion having a pitting potential.

## Claims

### Claim 1

A joining structure having a welded part for connecting joined members made of a metal that forms a passive film when the metal is welded, wherein
an outermost surface portion of the welded part has a pitting potential;
the welded part comprises:
a welded part main body formed inside, and
a surface-modified layer formed in contact with the welded part main body;
the surface-modified layer includes the outermost surface portion having the pitting potential and a portion formed by remelting and solidifying a melt-semi-solidified metal;
the welded part is formed by remelting and solidifying only the portion of the surface-modified layer without remelting the welded part main body, which is deeper than the surface-modified layer, such that formation of a keyhole in the welded part is prevented;
the portion of the surface-modified layer formed by remelting and solidifying the melt-semi-solidified metal has a depth range of 0.5 μm or greater and 100 μm or smaller from the outermost surface portion of the welded part in a welding depth direction such that thermal deformation is suppressed; and
after remelting and solidifying the portion of the surface-modified layer, spinel oxide is not detectable by an X-ray absorption fine structure analysis of the outermost surface portion of the surface-modifier layer due to the portion of the surface-modified layer of the welded part being remelted and solidified to prevent formation of the keyhole.

### Claim 2 (depends on 1)

The joining structure according to claim 1, wherein
a maximum diameter of the surface-modified layer is equal to or larger than a maximum diameter of the welded part main body as viewed in a cross section in a welding depth direction.

### Claim 3 (depends on 1)

The joining structure according to claim 1, wherein
the surface-modified layer has a plurality of weld beads arranged so that adjacent weld beads overlap with each other.

### Claim 4 (depends on 1)

The joining structure according to claim 1, wherein
the surface-modified layer has a single weld bead.

### Claim 5 (depends on 1)

The joining structure according to claim 1, wherein the welded part is made of Cr, Cr alloy, Al, Al alloy, Ti, or Ti alloy.