Resistance spot welding method and weld joint

• US 10,641,304 B2
• Filed: 03/03/2016
• Issued: 05/05/2020
• Est. Priority Date: 03/05/2015
• Status: Active Grant

• Current Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Original Assignee: JFE Steel Corporation (JFE Holdings Incorporated)
• Inventors: Taniguchi, Koichi, Okita, Yasuaki, Ikeda, Rinsei
• Primary Examiner(s): Nguyen, Hung D
• Application Number:
  US15/554,915
• Publication Number:
  US 20180038402A1
• Time in Patent Office: 1,524 Days
• Field of Search: 219 7801, 219 861, 219 8622, 219 8623, 219 8641, 219 8651, 219 8661, 219 867, 219 911, 219 92, 219108, 2191171, 219 912
• CPC Class Codes: B23K 11/11 Spot welding
• CPC Class Codes: B23K 11/16 taking account of the properties of the material to be welded
• CPC Class Codes: B23K 11/163 Welding of coated materials
• CPC Class Codes: B23K 2101/34 Coated articles , e.g. plated or painted; Surface treated articles
• CPC Class Codes: B23K 2103/04 Steel or steel alloys
• CPC Class Codes: F16B 5/08 by means of welds or the like welding B23K

Abstract

Provided is a method for resistance spot-welding at least two overlapping steel sheets. When an electrode force F after an electric current supply is started changes from an initial electrode force Fi to an electrode force F_h⁽¹⁾ while a lapse from the start of the electric current supply is between 20 ms and 80 ms inclusive, a suspension of the electric current supply of from 20 ms to 60 ms inclusive is started. Then the electric current supply is resumed when the electrode force F reaches an electrode force F_c⁽¹⁾.

Claims

1. A resistance spot welding method for resistance spot-welding at least two steel sheets overlapping each other, the method comprising:

starting a suspension of an electric current supply of from 20 ms to 60 ms inclusive when an electrode force F after the electric current supply is started changes from an initial electrode force Fi to an electrode force F_h⁽¹⁾ represented by formula (1)

1.03×

Fi≤

F_h⁽¹⁾≤

1.15×

Fi, 

 

(1)

while a lapse from the start of the electric current supply is between 20 ms and 80 ms inclusive; and

resuming the electric current supply when the electrode force F reaches an electrode force F_c⁽¹⁾ represented by formula (2);

1.01×

Fi≤

F_c⁽¹⁾≤

0.99×

F_h⁽¹⁾ 

 

(2).

2. The resistance spot welding method according to claim 1, further comprising,

after the suspension of the electric current supply, repeating at least once the electric current supply of from 20 ms to 80 ms inclusive and the suspension of the electric current supply of from 20 ms to 60 ms inclusive such that,

when the electrode force F during an Nth electric current supply changes from an electrode force F_c^(N−

1) immediately after an (N−

1)th suspension of the electric current supply to an electrode force F_h^(N) represented by formula (3),

1.04×

F_c<sup>(N−

1)</sup>≤

F_h^(N)≤

1.15×

F_c<sup>(N−

1)</sup>, 

 

(3)

the suspension of the electric current supply is started, and then,

the electric current supply is resumed when the electrode force F reaches an electrode force F_c^(N) represented by formula (4);

F_c<sup>(N−

1)</sup>≤

F_c^(N)≤

0.99×

F_h^(N), 

 

(4)

wherein N is a natural number of 2 or more.

3. The resistance spot welding method according to claim 2, wherein the period of a last repetition of the electric current supply is from 100 ms to 300 ms inclusive.

4. The resistance spot welding method according to claim 2, wherein at least one of the at least two steel sheets comprises 0.15≤

C≤

0.30 (% by mass), 1.9≤

Mn≤

5.0 (% by mass), and 0.2≤

Si≤

2.0 (% by mass).

5. The resistance spot welding method according to claim 2, wherein at least one of the at least two steel sheets has a tensile strength of 980 MPa or more.

6. The resistance spot welding method according to claim 2, wherein at least one of the at least two steel sheets has, on a surface thereof, a coating layer containing zinc as a main component.

7. The resistance spot welding method according to claim 1, wherein the period of a last repetition of the electric current supply is from 100 ms to 300 ms inclusive.

8. The resistance spot welding method according to claim 7, wherein at least one of the at least two steel sheets comprises 0.15≤

C≤

0.30 (% by mass), 1.9≤

Mn≤

5.0 (% by mass), and 0.2≤

Si≤

2.0 (% by mass).

9. The resistance spot welding method according to claim 7, wherein at least one of the at least two steel sheets has a tensile strength of 980 MPa or more.

10. The resistance spot welding method according to claim 7, wherein at least one of the at least two steel sheets has, on a surface thereof, a coating layer containing zinc as a main component.

11. The resistance spot welding method according to claim 1, wherein at least one of the at least two steel sheets comprises 0.15≤

C≤

0.30 (% by mass), 1.9≤

Mn≤

5.0 (% by mass), and 0.2≤

Si≤

2.0 (% by mass).

12. The resistance spot welding method according to claim 11, wherein at least one of the at least two steel sheets has a tensile strength of 980 MPa or more.

13. The resistance spot welding method according to claim 11, wherein at least one of the at least two steel sheets has, on a surface thereof, a coating layer containing zinc as a main component.

14. The resistance spot welding method according to claim 1, wherein at least one of the at least two steel sheets has a tensile strength of 980 MPa or more.

15. The resistance spot welding method according to claim 14, wherein at least one of the at least two steel sheets has, on a surface thereof, a coating layer containing zinc as a main component.

16. The resistance spot welding method according to claim 1, wherein at least one of the at least two steel sheets has, on a surface thereof, a coating layer containing zinc as a main component.