BONDING METHOD OF DISSIMILAR MATERIALS MADE FROM METALS AND BONDING STRUCTURE THEREOF

• US 20080241572A1
• Filed: 03/17/2008
• Published: 10/02/2008
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Miyamoto, Kenji, Nakagawa, Shigeyuki
• Granted Patent: US 8,058,584 B2
• Time in Patent Office: Days
• US Class Current: 428/600
• CPC Class Codes: B23K 11/115 by means of two electrodes placed opposite one another on both sides of the welded parts
• CPC Class Codes: B23K 11/20 of different metals
• CPC Class Codes: B23K 2103/20 Ferrous alloys and aluminium or alloys thereof
• CPC Class Codes: Y10T 428/12028 Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, etc.]
• CPC Class Codes: Y10T 428/12389 having variation in thickness
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

Disclosed is a bonding method for dissimilar materials made from metals and its resulting structures. The materials to be bonded are formed by layering three or more sheets such that a dissimilar material interface and a same material interface are formed. A first current is conducted between a three-sheet layered plate material wherein an aluminum alloy plate, a zinc plated steel plate and a bare steel plate, for example, are layered in order. A nugget is formed in an interface between the zinc plated steel plate and the bare steel plate, which are the same materials. Then, a second current greater than the first current is conducted, and a nugget is formed in an interface between the aluminum alloy plate and the zinc plated steel plate.

Claims

1. A method of bonding dissimilar materials made from metals, the method comprising:

layering a plurality of plate materials, wherein at least two of the plate materials are a first metallic material and at least one plate material is a second metallic material having a melting point lower than the first metallic material, to form a dissimilar material interface and a same material interface;

forming a layered seam by a resistance welding operation in which a contact resistance of the dissimilar material interface is lower than a contact resistance of the same material interface;

conducting a first current across at least three layers of the plurality of layered plate materials to form a nugget in the same material interface; and

conducting a second current greater than the first current across the at least three layers of the plurality of layered plate materials to form a nugget in the dissimilar material interface.

2. The method according to claim 1, further comprising:

monitoring the contact resistance of the same material interface while conducting the first current; and

switching the first current to the second current according to a decrease in the contact resistance of the same material interface.

3. The method according to claim 1, further comprising:

roughening a surface of at least one plate material forming the dissimilar material interface prior to conducting the first current and the second current, wherein a roughness of the surface is greater than a surface roughness of at least one plate material forming the same material interface.

4. The method according to claim 1, further comprising:

smoothing a surface of at least one plate material forming the same material interface prior to conducting the first current and the second current, wherein a roughness of the surface is finer than a surface roughness of at least one plate material forming the dissimilar material interface.

5. The method according to claim 1, further comprising:

interposing a material that increases an electric resistance of the dissimilar material interface into the dissimilar material interface prior to conducting the first current and the second current.

6. The method according to claim 1, further comprising:

interposing a seal material into the dissimilar material interface prior to conducting the first current and the second current.

7. The method according to claim 1 wherein the first metallic material is steel and the second metallic material is an aluminum alloy.

8. The method according to claim 1 wherein the first metallic material is steel and the second metallic material is a magnesium alloy.

9. The method according to claim 1, further comprising:

interposing a material that eutecticly fuses with at least one plate material forming the dissimilar material interface into the dissimilar material interface prior to conducting the first current and the second current.

10. The method according to claim 9, further comprising:

introducing a seal material between the interposed material and the other plate material forming the dissimilar material interface prior to conducting the first current and the second current.

11. The method according to claim 6 wherein the interposed material is a material plated on a surface of the first metallic material forming the dissimilar material interface.

12. The method according to claim 11 wherein the plated material is at least one of copper (Cu), tin (Sn), silver (Ag), nickel (Ni) and zinc (Zn).

13. A bonded structure of dissimilar materials made from metals obtained by the method of claim 11.

14. A bonded structure of dissimilar materials made from metals, comprising:

at least two plates layers of a first metallic material;

at least one plate layer of a second metallic material having a melting point lower than the first metallic material;

a dissimilar material interface between a plate layer of the first metallic material and a plate layer of the second metallic material;

a same material interface between adjacent plate layers of the first metallic material, wherein a contact resistance in the dissimilar material interface is lower than a contact resistance in the same material interface;

a nugget formed in the dissimilar material interface having a first diameter Dd; and

a nugget formed in the same material interface having a second diameter Ds, wherein the first diameter Dd is equal to or larger than the second diameter Ds.

15. The bonded structure according to claim 14 wherein the first diameter Dd is within a range of 4.4√

t1<

Dd<

12√

t1, with t1 being a thickness of one of the plate layers forming the dissimilar material interface that has a smaller product; and

wherein the second diameter Ds is within a range of 4√

t2<

Ds<

7√

t2, with t2 being a thickness of one of the plate layers forming the same material interface that has a smaller product; and

wherein a product of a respective plate layer is defined as a strength per unit area multiplied by a thickness of the respective plate layer.

16. A vehicular component comprising the bonded structure of claim 15.