Spot welded joint and spot welding method

Patent metadata

Field	Value
Publication number	US-10646949-B2
Application number	US-201515032106-A
Country	US
Kind code	B2
Filing date	Jan 30, 2015
Priority date	Jan 31, 2014
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

The present invention has as its object to provide a spot welded joint and spot welding method which raise the fracture toughness of spot welded metal to raise the strength of the spot welded joint. In the present invention, there is provided a spot welding method comprising a melt zone forming step forming a melt zone by conduction and, after the melt zone forming step, a solidification step of running a current lower than the current run in the melt zone forming step so as to cause the melt zone to solidify, wherein, in the solidification step, electromagnetic vibration is applied to the melt zone, and a frequency fV of the electromagnetic vibration, a solidification speed νS when the melt zone solidifies, and an arm interval of dendrites λD when the melt zone solidifies satisfy 0.2≤νS/(λD·fV)≤4.0.

First claim

The invention claimed is:

1. A spot welding method comprising:
superposing at least two steel sheets;
forming a melt zone by conduction,
wherein the conduction is performed by running a current having a value,
after said melt zone forming, forming a solidified structure in the melt zone running another current of which value is lower than the value for forming the melt zone, and applying an electromagnetic vibration, and
wherein a frequency f V of the electromagnetic vibration, a solidification speed ν S when the melt zone solidifies, and an arm interval of dendrites λ D when the melt zone solidifies satisfy 0.2≤ν S /(λ D ·f V )≤4.0, and
the solidification speed ν S and the arm interval of the dendrites λ D are obtained by advance experiments, wherein:
the solidification speed ν S and the arm intervals of the dendrites λ D are obtained by applying spot welding to samples of which combination of sheet and type of steel are the same as in the steel sheets to be welded while putting time of running current under plural conditions.

Assignees

• Nippon Steel & Sumitomo Metal Corp
• Nippon Steel Corp

Inventors

• Watanabe Fuminori
• Miyazaki Yasunobu

Classifications

• B23K11/12

  making use of vibrations · CPC title

• B23K2101/006

  Vehicles · CPC title

• B23K11/16

  taking account of the properties of the material to be welded · CPC title

• B23K11/11 Primary

  Spot welding · CPC title

• B23K2103/04

  Steel {or steel} alloys · CPC title