Electric current-assisted joining of similar/dissimilar materials

Resistance spot welding (RSW) is the most widely used for joining thin sheet metals in automotive industry. Various applications of dissimilar materials and thicknesses were commonly found in many spot welding processes especially in the manufacture of car body. The resistance spot welding of dissimilar materials are generally more challenge than similar materials due to differences in the physical, chemical, and mechanical properties of the base metals. Differences of materials have an impact on heat input generated at the spot welding. Diameter of the weld nugget size is influenced by several parameters such as electric current, welding time, different types of material, and the thickness of the plate. Nugget diameter will influence on physical and mechanical properties weld such as microstructure, shear strength and hardness. For practical use, various industrial standards have recommended a minimum weld size for a given sheet thickness, mostly in the form of tables. For example the American Welding Society (AWS), Society of Automotive Engineering (SAE) and the American National Standards Institute (ANSI). They were only suitable to be apllied on the similar metal and thickness joint because in this joint, symetrical nugget will be formed. Meanwhile a type of dissimilar metal that joined by spot welding method will result in the asymetrical nugget. This paper aims to review the results of researchs on the similar and dissimilar resistance spot welded joint to evaluate the use of similar metals weld parameters and standards on the dissimilar metals weld. It was determined that parameters welding such as electric current, welding time, and the standard for similar metals weld can not be applied on the dissimilar metals weld. The asymetrical nugget shape decreased shear strength on the weld nugget. The most important factor that was considered on the dissimilar metals weld to make high quality weld joint was nugget diameter. If the nugget diameter weld increased the strength of welding will increase.

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Joining Dissimilar Materials by Pulsed Electric Current Bonding

Journal of High Temperature Society ◽

10.7791/jhts.37.192 ◽

2011 ◽

Vol 37 (4) ◽

pp. 192-196

Author(s):

Akio NISHIMOTO

Keyword(s):

Electric Current ◽

Dissimilar Materials ◽

Pulsed Electric Current

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Analytical and High-Resolution EM Study of Crystalline Phases formed at Metal-Ceramic Interface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135733 ◽

1990 ◽

Vol 48 (2) ◽

pp. 426-427

Author(s):

N. Merk ◽

A. P. Tomsia ◽

G. Thomas

Keyword(s):

Cross Section ◽

Dissimilar Materials ◽

Ceramic Materials ◽

Electron Micrograph ◽

Scanning Electron Micrograph ◽

Structural Applications ◽

Metal Ceramic ◽

The Subject ◽

Ceramic Compounds ◽

Scanning Electron

A recent development of new ceramic materials for structural applications involves the joining of ceramic compounds to metals. Due to the wetting problem, an interlayer material (brazing alloy) is generally used to achieve the bonding. The nature of the interfaces between such dissimilar materials is the subject of intensive studies and is of utmost importance to obtain a controlled microstructure at the discontinuities to satisfy the demanding properties for engineering applications . The brazing alloy is generally ductile and hence, does not readily fracture. It must also wett the ceramic with similar thermal expansion coefficient to avoid large stresses at joints. In the present work we study mullite-molybdenum composites using a brazing alloy for the weldment.A scanning electron micrograph from the cross section of the joining sequence studied here is presented in Fig. 1.

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Interfacial structures of dissimilar materials joined by capacitor-discharge welding

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170402 ◽

1994 ◽

Vol 52 ◽

pp. 534-535

Author(s):

C. P. Doğan ◽

R. D. Wilson ◽

J. A. Hawk

Keyword(s):

Rapid Solidification ◽

Fusion Zone ◽

Dissimilar Materials ◽

Solidification Process ◽

Weld Interface ◽

Capacitor Discharge ◽

Fine Grained ◽

Iron Aluminum ◽

Conductive Ceramics ◽

Capacitor Discharge Welding

Capacitor Discharge Welding is a rapid solidification technique for joining conductive materials that results in a narrow fusion zone and almost no heat affected zone. As a result, the microstructures and properties of the bulk materials are essentially continuous across the weld interface. During the joining process, one of the materials to be joined acts as the anode and the other acts as the cathode. The anode and cathode are brought together with a concomitant discharge of a capacitor bank, creating an arc which melts the materials at the joining surfaces and welds them together (Fig. 1). As the electrodes impact, the arc is extinguished, and the molten interface cools at rates that can exceed 106 K/s. This process results in reduced porosity in the fusion zone, a fine-grained weldment, and a reduced tendency for hot cracking.At the U.S. Bureau of Mines, we are currently examining the possibilities of using capacitor discharge welding to join dissimilar metals, metals to intermetallics, and metals to conductive ceramics. In this particular study, we will examine the microstructural characteristics of iron-aluminum welds in detail, focussing our attention primarily on interfaces produced during the rapid solidification process.

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