Explosive Welding and Metal Composites (2)

As described above, the explosive weld bond zone is characterized by plastic deformation, melting and diffusion of the metal. In conventional welding processes, these features are unique to single pressure welding, single fusion welding, and single diffusion welding. That is to say, the mechanism of explosive welding "combined" or "fused" three mechanisms of pressure welding, fusion welding and diffusion welding. It can be inferred that explosive welding is a new welding technique of "trinity" of pressure welding, fusion welding and diffusion welding. The reason why explosive welding can weld almost all combinations of metal materials in a flash, the reason why explosive composites have high bonding properties, may be here. This is the physics of explosive welding.

2 characteristics of explosive welding

The new process and new technology of explosive welding can exist independently, and it can be rapidly developed and widely used in a short period of time. The main reason is that it has many features and advantages as follows.

2.1 Characteristics of the discipline

Metal explosive welding is a marginal discipline between metal physics, explosive physics and welding processes. The basic theories of these three disciplines provide the necessary theoretical basis for its research and development. The establishment of explosive welding theory will also add a new chapter to metal materials science, explosive physics and welding science.

2.2 Characteristics of energy

Any metal welding requires some form of energy. The energy of explosive welding is the chemical energy of explosives. This chemical energy can be converted, absorbed, transferred and distributed multiple times and in various forms of energy in an explosive-explosion-metal system during the explosive welding process, and finally a weld bond between the metals is formed. This process is in microseconds in time.

2.3 Process characteristics

Explosive welding processes and operations are simple. It does not require expensive equipment and highly skilled technology. In fact, as long as there are explosives, metal materials and an open field (explosive field), as well as a small number of auxiliary equipment and tools, explosive welding tests and production can be carried out under the operation of a little technical training and practical experience. Moreover, its scope and scale can be rapidly expanded with the expansion of the market, the increase of staff and the improvement of mechanization.

2.4 Characteristics on welding

According to the data, more than 300 pairs of metals with the same physical, chemical properties, and similar disparity have been welded by the explosive welding method. Plates and plates, plates and tubes, tubes and tubes, tubes and tube sheets, tubes and rods, and shaped parts can be explosively welded. Explosive welding of honeycomb structures with complex shapes, dozens of layers and hundreds of layers of metal foils was successful. Metal and glass, plastic and ceramic can also be explosively welded together. In principle, explosive welding provides an irreplaceable process and method for the simple, rapid and efficient welding of the same metal, especially different metals, in large areas, high quality and in many forms.

2.5 Characteristics on the welding transition zone

Explosive welding of bimetallic and polymetallic bonding regions is a transition zone between composition, organization and properties of the matrix metal. In general it has the distinct characteristics of plastic deformation, melting, diffusion and waveform of the metal. This transition zone is usually very narrow, typically in the range of 0.01 to 1 mm. Although small in size, it is a strong bond to the base metal. The formation of this bond, its organization and properties are directly related to the process parameters, and also directly affect the bond strength and performance between the base metals. Therefore, the formation, causes and results of the explosive welding transition zone (bonding zone) are an important part of the theoretical research of this discipline.

2.6 Performance characteristics

The bond strength of an explosive composite is generally comparable to the strength of a weaker substrate. Because of this, composite materials such as titanium-steel and stainless steel-steel are able to withstand subsequent leveling, drum, cutting, welding, stamping, spinning, forging, extrusion, drawing, rolling and Heat treatment, as well as explosion forming, etc. without delamination and cracking.

After the explosion load, the base metal will harden and strengthen to some extent. However, some of their special physical and chemical properties, such as the corrosion resistance of corrosion resistant materials, the electrical conductivity of conductive materials, the thermodynamic properties of thermal bimetals, magnetic properties, acoustic properties, superconducting properties and nuclear properties are generally not change. In other words, they maintain their original performance.

3 Explosive welding applications

The application of explosive welding can be summarized as follows, and these applications are also a major feature.

3.1 Provides a new welding process and technology

The use of various new energy sources has greatly promoted the development of welding technology, which is a newly opened one in this field. As a welding science classification in the field of special welding, it provides another new process and new technology for the welding of the same, especially different metal materials. A large number of facts show that explosive welding is a major development in welding science.

3.2 Provides a new production process for composite materials

So far, there have been many production methods for metal composite materials. For example, a lamination method, a smelting method, a surfacing method, an electroplating method, a coating method, a powder metallurgy method, a vapor deposition method, a co-extrusion method, and a co-drawing method. The explosive welding method provides another rare new process and new technology for the production of composite materials of any metal combination. Especially after the combination of conventional pressure processing technologies such as explosive welding and rolling, the effects and benefits will be unmatched by other methods for producing metal composite materials.

3.3 A new set of metal composite structural material systems is provided

If based on literature, the composition of such a composite structural material system can be as listed in Tables 1 to 4.

Table 1 Bimetal composite structural materials

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