Method of welding overlapped portion, method of manufacturing overlap-welded member, overlap-welded member, and automotive part

Patent metadata

Field	Value
Publication number	US-10549388-B2
Application number	US-201314409417-A
Country	US
Kind code	B2
Filing date	Aug 8, 2013
Priority date	Aug 8, 2012
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

A method of welding an overlapped portion according to the present invention in which a plurality of steel sheet members are joined at an overlapped portion, and at least one of the plurality of steel sheet members contains martensite, includes: forming a spot-welded portion having a nugget in the overlapped portion; and emitting a laser beam to form a melted and solidified portion crossing an end of the nugget and located between the nugget and a position externally spaced apart from an end of the nugget by not less than 3 mm, this melted and solidified portion being formed in the steel sheet member containing the martensite so as to have a depth of not less than 50% of the thickness of the steel sheet member containing the martensite at a position externally spaced apart from the end of the nugget by 1 mm.

First claim

The invention claimed is:

1. A method of welding an overlapped portion in which a plurality of steel sheet members are joined at the overlapped portion, the method including:
arranged an overlapped portion of the plurality of steel sheet members, wherein at least one of the plurality of steel sheet members contains martensite, and the plurality of steel sheet members comprise steel sheets in which a heat affected zone (HAZ) softened portion of which a hardness is less than a base material is scheduled to be formed by a spot welding, the method including;
forming a spot-welded portion having a nugget in the overlapped portion; and
reducing the area of a HAZ softening zone of the spot-welded portion by forming a melted and solidified portion crossing an end of the nugget, the melted and solidified portion being formed in the steel sheet member containing the martensite so as to have a depth of not less than 50% of a thickness of the steel sheet member containing the martensite at a position externally spaced apart from the end of the nugget by 1 mm, wherein forming the melted and solidified portion comprises: emitting a laser beam from a position which is located between the nugget and a position externally spaced apart from the end of the nugget by not less than 3 mm; emitting the laser beam to run in a direction along a longitudinal direction of the steel sheet member containing the martensite to intersect with the spot-welded portion such that direction of run of the laser beam crosses the end of the nugget so as to have an intersection angle θ within ±30° with respect to an expected direction of stress.

2. A method of manufacturing an overlap-welded member, including:
overlapping a plurality of steel sheet members at an overlapped portion; and
performing a welding in accordance with the method of welding the overlapped portion according to claim 1 .

3. An automotive part which includes the overlap-welded member according to claim 2 .

Assignees

• Nippon Steel & Sumitomo Metal Corp
• Nippon Steel Corp

Inventors

• Fujimoto Hiroki
• Okada Tohru
• Yasuyama Masanori

Classifications

• B23K26/32

  taking account of the properties of the material involved · CPC title

• B23K26/244

  Overlap seam welding · CPC title

• B23K11/115 Primary

  by means of two electrodes placed opposite one another on both sides of the welded parts · CPC title

• B23K2103/08

  Non-ferrous metals or alloys · CPC title

• B23K28/02 Primary

  Combined welding or cutting procedures or apparatus · CPC title