Method for resistance spot welding
AssigneeJfe Steel Corporation
InventorsNao KAWABE, Chikaumi SAWANISHI, Katsutoshi TAKASHIMA
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Abstract
A method for resistance spot welding for two or more steel sheets includes performing main energizing for forming a nugget, cooling, post-energizing, and holding. The cooling, the post-energizing, and the holding are performed after the main energizing. Cooling time Ct in the cooling is more than or equal to 140 ms, and holding time Ht (ms) in the holding satisfies expression (1) or expression (2) below: when Ct ≤ 2 × D × √ TS - 80 , ( 1 ) D × √ TS - 0.5 × Ct < Ht ≤ 2700 × D / √ TS + Ct . when Ct > 2 × D × √ TS - 80 , 40 < Ht ≤ 2700 × D / √ TS + Ct . ( 2 )
Claims8
A method for resistance spot welding,
- wherein two or more steel sheets including at least one surface treated steel sheet having a metal coated layer are caused to overlap each other to form a sheet set, and the sheet set is clamped and pressurized by a pair of welding electrodes while being energized so as to be joined to each other,
- wherein the method comprises:
- performing main energizing for forming a nugget;
- cooling;
- post-energizing;
- and
- holding, wherein
- the cooling, the post-energizing, and the holding are performed after the main energizing,
- cooling time Ct (ms) in the cooling is more than or equal to 140 ms, and
- holding time Ht (ms) in the holding satisfies expression (1) or expression (2) below:
- when
-
- Ct
- ≤
- 2
- ×
- D
- ×
- √
- TS
- -
- 80
- ,
- (
- 1
- )
- D
- ×
- √
- TS
- -
- 0.5
- ×
- Ct
- <
- Ht
- ≤
- 2700
- ×
- D
- /
- √
- TS
- +
- Ct
- ,
- when
-
- Ct
- >
- 2
- ×
- D
- ×
- √
- TS
- -
- 80
- ,
- 40
- <
- Ht
- ≤
- 2700
- ×
- D
- /
- √
- TS
- +
- Ct
- ,
- (
- 2
- )
- in expression (1) and expression (2), D is a total thickness (mm) of the sheet set, and TS is a tensile strength (MPa) of a steel sheet having a highest tensile strength in the sheet set.
Dependencies are inferred from the claim text.