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Electrode system for improving performances of steel-aluminum dissimilar metal resistance spot welding head

A technology of dissimilar metals and electrode systems, applied in resistance welding equipment, welding media, welding equipment, etc., can solve the problems of deterioration of mechanical properties of welded joints, intermetallic compounds, easy cracks, etc., and improve the interface structure and bonding form of joints. , the effect of reducing the degree of atomic diffusion and reducing the growth rate

Inactive Publication Date: 2017-05-31
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Resistance spot welding of steel and aluminum dissimilar metals is one of the most important welding methods in the lightweight production of automobile bodies, but there is a technical problem to be solved urgently in the resistance spot welding of these two materials: due to the physical properties of steel and aluminum (for example, Melting point, linear expansion coefficient, thermal conductivity and solid solubility, etc.) are obviously different, and defects such as cracks and intermetallic compounds (Intermetallic Compound English abbreviation for IMC) are prone to occur during welding
Due to the formation of brittle intermetallic compounds, the mechanical properties of welded joints are deteriorated under the action of external tensile stress

Method used

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  • Electrode system for improving performances of steel-aluminum dissimilar metal resistance spot welding head
  • Electrode system for improving performances of steel-aluminum dissimilar metal resistance spot welding head
  • Electrode system for improving performances of steel-aluminum dissimilar metal resistance spot welding head

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] An electrode system used to improve the performance of spot welding joints of steel and aluminum dissimilar metals, in which the positive electrode is a ring electrode, and the negative electrode is a flat electrode. Their overall shape is a cylindrical structure, and the diameter of the end face is The electrode end face of the flat electrode is a flat end face, and the end face of the ring electrode has an outer circular groove and an inner circular groove. The diameter of the spot welding electrode is 20mm, and the diameter of the spherical surface is 50mm. The distance from the axis at the flat end face is and Each position has an annular groove with a depth of 200um and a width of 0.8mm. The diameter of the central circular platform 6

[0045] During spot welding, the positive electrode touches the surface of the aluminum plate, and the negative electrode touches the surface of the high-strength steel, resulting in a small indentation. At this time, the spo...

Embodiment 2

[0049] Same as Example 1, the difference is that the positive electrode 4 adopts a traditional ball electrode, the negative electrode 3 adopts a flat end face electrode, spot welding 1.2mm 6061 aluminum alloy + 1.2mm galvanized dual-phase steel, and the nugget after welding with the same heat input 5 has a diameter of 6.9 mm. Compared with the ring electrode of Comparative Example 1, more air hole defects are generated in the center of the nugget 5 .

[0050] Figure 7 As shown, the joint IMC welded by the ball electrode consists of heterogeneous iron-aluminum compound near the steel side and needle-like compound near the aluminum side. Its thickness is less than 3 μm.

Embodiment 3

[0052] Same as in Example 2, the positive electrode 4 is a traditional spherical electrode, the negative electrode 3 is a flat end electrode, spot welding 1.2 mm 6061 aluminum alloy + 1.2 mm galvanized dual-phase steel, and adjusting the welding parameters to obtain the same nugget diameter as in Example 1.

[0053] Table 1 is a comparison of the joint tensile shear performance (N) and fracture mode obtained by using the traditional ball electrode and the electrode with a circular groove on the ball end surface of the present invention (the data in Table 1 are the average value of multiple tests).

[0054] Table 1 Tensile shear performance (N), comparison of fracture modes

[0055] Nugget diameter (mm) Tensile shear performance (N) fracture mode ball electrode 7.4 4647 interface fracture ring electrode 7.4 5270 button break

[0056] As shown in Table 1, under the same nugget diameter, the tensile shear strength of the ball electrode is 464...

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Abstract

The invention relates to an electrode system for improving performances of a steel-aluminum dissimilar metal resistance spot welding head. The system comprises a pair of positive electrode and negative electrode, which are arranged oppositely and have different end face structures; the end face of the positive electrode is a ball end face and is in contact with the surface of an aluminum part to be machined; two annular grooves, which are concentrically arranged and have different radiuses, are formed in the ball end face; and the end face of the negative electrode is a fat end face and is in contact with the surface of a steel part to be machined. Compared with the prior art, heat distribution of a steel-aluminum interface can be effectively improved, the growth of an IMC (Intermetallic Compound) on a connector interface is weakened, a stable button breaking mode is obtained, and the reliability of a connector in connection is improved.

Description

technical field [0001] The invention belongs to the technical field of connection of dissimilar materials, and relates to an electrode system, in particular to an electrode system for improving the performance of resistance spot welding joints of steel and aluminum dissimilar metals. Background technique [0002] Against the background of energy shortage and increasing environmental pollution, lightweight, energy saving, environmental protection and safety have become the inevitable trend of the development of today's automobile industry. The ways to achieve lightweight in the domestic and foreign automobile industries include: adopting lightweight materials, optimizing the design of lightweight structures, and using new manufacturing techniques. High-strength steel and aluminum alloys are the main lightweight materials, followed by magnesium alloys, composite materials and plastics. Therefore, increasing the application of lightweight materials such as high-strength steel ...

Claims

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Application Information

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IPC IPC(8): B23K35/02B23K11/11B23K103/20
CPCB23K35/0255B23K11/115B23K2103/20
Inventor 张敏孔谅王敏王炜杰陈楠楠刘思源
Owner SHANGHAI JIAO TONG UNIV
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