Spot welded member

Patent metadata

Field	Value
Publication number	US-12037665-B2
Application number	US-201917414111-A
Country	US
Kind code	B2
Filing date	Dec 19, 2019
Priority date	Dec 21, 2018
Publication date	Jul 16, 2024
Grant date	Jul 16, 2024

Abstract

A spot welded member includes a spot weld formed by holding a sheet stack of multiple steel sheets between a pair of electrodes and spot-welding the sheet stack, in which at least one of the multiple steel sheets is a high-strength zinc-based coated steel sheet having a tensile strength of 780 MPa or more, the high-strength zinc-based coated steel sheet having a coating with an Al content of 0.5% or more by mass, and in which the heat shock region of the spot weld outwardly extending from an edge of a corona bond area includes a coated layer including an FeAl alloy layer having an average thickness of 0.3 μm or more and a zinc-based coated layer having an average thickness of 2.0 μm or more on the FeAl alloy layer at the interface between the base steel sheet of the high-strength zinc-based coated steel sheet and the coating.

First claim

The invention claimed is:

1. A spot welded member, comprising a spot weld formed by holding a sheet stack of multiple steel sheets between a pair of electrodes and spot-welding the sheet stack,
wherein the spot welded member comprises a region A and a region B the region B being a heat shock region of the spot weld outwardly extending from an edge of a corona bond area to adjacent region A,
wherein at least one of the multiple steel sheets is a high-strength zinc-based coated steel sheet having a tensile strength of 780 MPa or more, the high-strength zinc-based coated steel sheet having a first zinc-based coating with an Al content of 0.5% or more by mass, in the region A, on a base steel sheet, and
wherein the region B includes a coated layer B including an FeAl alloy layer disposed on a surface of the base steel sheet, and a second zinc-based coated layer, disposed on the FeAL alloy laver,
wherein the FeAL alloy layer has an average thickness of 0.3 μm or more and the second zinc-based coated layer has an average thickness of 2.0 μm or more.

2. The spot welded member according to claim 1 , the Al content of the first zinc-based coating satisfies formula (1):
[Average thickness of FeAl alloy layer]≥0.8×In[Al content]+0.2  (1)

where In is a natural logarithm, [average thickness of FeAl alloy layer] is the average thickness (μm) of the FeAl alloy layer, and [Al content] is the Al content (% by mass) of the first zinc-based coating.

3. The spot welded member according to claim 1 , wherein the coated layer B further includes a Zn-rich phase (n) having an Fe content of 5% or less by mass.

4. The spot welded member according to claim 2 , wherein the coated layer B further includes a Zn-rich phase (n) having an Fe content of 5% or less by mass.

5. The spot welded member according to claim 1 , wherein the Zn-rich phase (n) has (001) orientation with respect to a basal surface.

6. The spot welded member according to claim 2 , wherein the Zn-rich phase (n) has (001) orientation with respect to a basal surface.

7. The spot welded member according to claim 3 , wherein the Zn-rich phase (n) has (001) orientation with respect to a basal surface.

8. The spot welded member according to claim 4 , wherein the Zn-rich phase (n) has (001) orientation with respect to a basal surface.

9. The spot welded member according to claim 1 , wherein the base steel sheet of the zinc-based coated steel sheet has a component composition containing, by mass %:
C: 0.01% to 0.22%,
Si: 0.02% to 2.00%,
Mn: 1.0% to 4.0%,
P: 0.060% or less, and
S: 0.01% or less.

10. The spot welded member according to claim 2 , wherein the base steel sheet of the zinc-based coated steel sheet has a component composition containing, by mass %:
C: 0.01% to 0.22%,
Si: 0.02% to 2.00%,
Mn: 1.0% to 4.0%,
P: 0.060% or less, and
S: 0.01% or less.

11. The spot welded member according to claim 3 , wherein the base steel sheet of the zinc-based coated steel sheet has a component composition containing, by mass %:
C: 0.01% to 0.22%,
Si: 0.02% to 2.00%,
Mn: 1.0% to 4.0%,
P: 0.060% or less, and
S: 0.01% or less.

12. The spot welded member according to claim 4 , wherein the base steel sheet of the zinc-based coated steel sheet has a component composition containing, by mass %:
C: 0.01% to 0.22%,
Si: 0.02% to 2.00%,
Mn: 1.0% to 4.0%,
P: 0.060% or less, and
S: 0.01% or less.

13. The spot welded member according to claim 7 , wherein the base steel sheet of the zinc-based coated steel sheet has a component composition containing, by mass %:
C: 0.01% to 0.22%,
Si: 0.02% to 2.00%,
Mn: 1.0% to 4.0%,
P: 0.060% or less, and
S: 0.01% or less.

14. The spot welded member according to claim 8 , wherein the base steel sheet of the zinc-based coated steel sheet has a component composition containing, by mass %:
C: 0.01% to 0.22%,
Si: 0.02% to 2.00%,
Mn: 1.0% to 4.0%,
P: 0.060% or less, and
S: 0.01% or less.

15. The spot welded member according to claim 9 , wherein the component composition of the base steel sheet of the zinc-based coated steel sheet further contains, by mass %, one or two or more selected from the group consisting of:
Nb: 0.002% to 0.100%,
Ti: 0.002% to 0.100%, and
B: 0.0002% to 0.0050%.

16. The spot welded member according to claim 10 , wherein the component composition of the base steel sheet of the zinc-based coated steel sheet further contains, by mass %, one or two or more selected from the group consisting of:
Nb: 0.002% to 0.100%,
Ti: 0.002% to 0.100%, and
B: 0.0002% to 0.0050%.

17. The spot welded member according to claim 11 , wherein the component composition of the base steel sheet of the zinc-based coated steel sheet further contains, by mass %, one or two or more selected from the group consisting of:
Nb: 0.002% to 0.100%,
Ti: 0.002% to 0.100%, and
B: 0.0002% to 0.0050%.

18. The spot welded member according to claim 12 , wherein the component composition of the base steel sheet of the zinc-based coated steel sheet further contains, by mass %, one or two or more selected from the group consisting of:
Nb: 0.002% to 0.100%,
Ti: 0.002% to 0.100%, and
B: 0.0002% to 0.0050%.

19. The spot welded member according to claim 13 , wherein the component composition of the base steel sheet of the zinc-based coated steel sheet further contains, by mass %, one or two or more selected from the group consisting of:
Nb: 0.002% to 0.100%,
Ti: 0.002% to 0.100%, and
B: 0.0002% to 0.0050%.

20. The spot welded member according to claim 14 , wherein the component composition of the base steel sheet of the zinc-based coated steel sheet further contains, by mass %, one or two or more selected from the group consisting of:
Nb: 0.002% to 0.100%,
Ti: 0.002% to 0.100%, and
B: 0.0002% to 0.0050%.

Assignees

• Jfe Steel Corp

Inventors

• Tanaka Minoru
• Taniguchi Koichi
• SATO Rinta
• Takashima Katsutoshi
• Matsuda Hiroshi
• Ikeda Rinsei

Classifications

• C23C2/28

  Thermal after-treatment, e.g. treatment in oil bath · CPC title

• C23C2/40

  Plates; Strips · CPC title

• C23C2/06

  Zinc or cadmium or alloys based thereon · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C18/04

  with aluminium as the next major constituent · CPC title