What Is Explosion Welding?

Explosive welding refers to the process of melting two heterogeneous metal plates together using the energy of an explosive explosion. There are two forms of spot welding and wire welding, also known as explosive pressure welding. It is mainly used for welding composite plates of reaction tanks and storage tanks with little change in internal pressure and temperature. ^[1]

In the impact of the shrapnel and the target, people observed the solid-phase metallurgical bonding phenomenon during the severe collision between metals, but the earliest documented experiment closely related to explosive welding was provided by Carl of the United States. In 1944, Carl first observed the solid-phase welding of metal materials under high-speed collisions caused by explosives. In 1947, Deri.bas showed a photomicrograph of the bonding interface of a typical explosive welding composite plate. In 1957, the United States Phillipchuk successfully realized the explosive welding of aluminum and steel, and since then people have recognized the potential utility of explosive welding technology in the connection of metal components and metal material composites, and have begun to gradually expand theoretical research and engineering practice.

After the mid 1960s, the United States, Britain, Japan, the Soviet Union and other countries have started commercial production of explosive welding products. At the end of the 1960s, China has also started testing and production of explosive welding. Since the publication of "Explosive Machining" in the early 1980s, the theoretical research and engineering practice of explosive welding have flourished in China.

Explosive welding technology and explosive welding composite materials have been widely used in various fields such as petroleum, chemical industry, shipbuilding, electric power, aviation, aerospace, salt making, alkali making, metallurgy, atomic energy, mining, transportation and machinery manufacturing. The development of technology has opened up increasingly broad prospects. ^[2]

Welding of any metal requires some form of energy, for example,

It should be noted that explosive welding also has its shortcomings, deficiencies and limitations.

First of all, before grasping the use of explosives, a dangerous substance, people often have a certain sense of fear. This is a psychological obstacle that hinders the development of this discipline.

Second, explosion sounds and vibrations are not welcome.

Third, the implementation of this process is mostly carried out in the field, and it is difficult to avoid the influence of climate and weather.

Fourth, it is difficult to realize automation. In the era of low mechanization, the intensity of manual labor is still relatively large.

Fifth, it is difficult to apply welding to materials with abrupt cross sections, and welding of large thickness coatings is also difficult.

Sixth, for explosive welding of composite plates, the area cannot be infinite; the thickness of the cladding cannot be too thick, and the thickness of the base layer cannot be too thin.

Seventh, for materials with high strength and low plasticity, the welding strength is low; materials with low impact toughness are liable to embrittlement and crack at normal temperature.

Eighth, the theoretical basis of this discipline still has serious shortcomings. Especially under explosive loads, the behavior of metal materials under high pressure, high speed, high temperature and transient plastic deformation is not well studied, and the microstructure and properties of the bonding zone are not fully studied, and so on. Therefore, the mechanism of explosive welding has not been fully disclosed. ^[3]

Explosives are used in explosive welding, and explosives are a high-energy substance. If this material is used well, it will do useful work, otherwise it will have a great destructive effect, and even cause human casualties and property damage. Therefore, the safety of explosion welding is very important.

This problem exists throughout the transportation, storage and use of explosives. Therefore, care must be taken everywhere in the process. Relevant national departments and units have strict regulations and management systems for the purchase, transportation, storage and use of explosives and other pyrotechnic supplies. The matters that must be noted are emphasized as follows:

The explosion site should be located away from the building. The safe distance from the explosion point is greater than 1000 m for buildings and 100 ~ 300 m for humans.

Explosive depot managers must be on duty day and night, and outsiders must not enter; explosives,

The application areas of explosive welding and explosive composites can be summarized into two main aspects:

First, explosive welding, as a new process and technology of metal welding, is incomparable with known welding processes and technologies so far. In fact, as long as metal materials have a certain degree of plasticity and impact toughness, they can be explosively welded in any combination at room temperature. Even materials with low plasticity and impact toughness can be welded using thermal explosion methods.

For the welding of metal materials, the use of various new energy sources will promote the development of welding technology. The use of explosives as a huge energy source has made explosive welding a new welding technology opened up in this field.

Second, explosive welding is a new process and technology for the production of metal composite materials, which is its biggest use. In particular, the combination of explosive welding and various pressure processing and machining processes will eclipse the production methods and processes of other composite materials. No matter in variety, specification, output, quality, market, cost and benefit, explosive welding has obvious advantages. Practice has proved that the field of explosive composites is the enrichment and expansion of the material science system. Explosive composites are one of the new development directions and frontiers, and they are also an important frontier for sustainable development of materials. ^[3]