How explosion welding is performed, features of the original technology

Welding is the most common method of joining metal workpieces. However, the use of classical methods is not always possible. Difficulties arise when working with products that have different physical and chemical properties. The solution to the problem is explosion welding. It is used to create multilayer metal structures.

Explosive welding is a welding method based on the use of explosion energy.

Welding modes and process

Today, explosion welding is carried out without the use of precise modes and calculations. This is due to the fact that the technology has not yet been fully developed. That is why explosion welding can be considered more of an experimental processing method rather than an accurate one suitable for mass production. When considering the explosion welding process, attention should be paid to the following points:

1. A process has not been developed that produces an accurate result. Explosion welding is considered experimental.
2. After carrying out the procedure in question, it is difficult to predict the final result. This is due to the fact that it is practically impossible to control the blast wave.
3. The explosion welding scheme is developed based on the characteristics of the materials used. The main parameters are selected depending on the specific case.

Explosion welding process

It should be taken into account that there are pre-developed process parameters. They can be used to achieve specific results.

Material requirements

When welding metals with low ductility, difficulties may arise. Connecting parts made of fusible materials requires less energy. Surfaces must be protected from the negative effects of the blast wave. It is quite difficult to produce compositions from steel with titanium or aluminum using the explosion method. The process takes place at average parameters. When joining thick sheets, interlayers are used that do not form fragile compositions with the metals being welded. The strength of the seam also depends on the hardness of the parts.

We recommend reading Classification of the main types of fusion welding

Explosion welding allows you to obtain high-quality welded joints.

Explosion welding methods

Today, there are two main explosion welding schemes. This technology can be used for various alloys and metals. The production of bimetallic blanks is carried out as follows:

1. The main workpiece is located on the supporting foundation. It can be made by making concrete, which is strengthened with metal rods. In addition, a sand cushion is created to dampen the blast wave.
2. The technology involves moving a second sheet of metal, which is located at an angle of 3-10 percent relative to the first.
3. The explosives are evenly distributed along the length of the second sheet. A detonator is required to explode.
4. After a controlled explosion, the second sheet moves within a few fractions of seconds. Due to the strong impact, the individual metal sheets are connected.

A similar technology is used when it is necessary to pair sheet materials.

The second technology concerns the melting of pipes at the joint. In this case, explosion welding is also used. The features of this method include the following points:

1. An explosive is placed at the joint. It is worth considering that it should be located in the form of a ring-shaped strip.
2. In order to eliminate the possibility of deformation of the pipe itself, a metal core is inserted inside. If this is not done, the pipe may collapse.

Welding diagram at the explosion stage

Both technologies can lead to damage to the workpiece if the quantity and type of explosive is chosen incorrectly. That is why it is necessary to carry out accurate calculations.

What equipment is needed?

A targeted explosion requires special equipment. To carry out such work you will need:

1. Explosive. There are quite a large number of similar substances that can be used for explosions. Only a specialist can choose the most suitable one
2. Two pieces that need to be connected. They can be represented by sheet metal or cylindrical blanks.
3. A detonator that supplies current for an explosion.
4. If you are connecting small products, you can use a special chamber to carry out the explosion. It is usually located at the production site. In manufacturing, high-strength materials are used that can also withstand high temperatures.

The result of welding is bimetal

It is worth considering that to carry out the work you need to prepare a testing ground and an explosion site or a special chamber. Some elements are designed to redirect the blast wave, thereby increasing the effectiveness of the technology used.

Explosion welding technology

It is worth considering that the technology in question is characterized by quite a large number of features. Let's take the following points as an example:

1. It only takes a few moments to complete the connection. Due to the strong mechanical impact, a strong connection is created that can withstand severe mechanical stress.
2. The technology under consideration does not limit the size of the workpieces to be joined. If you need to melt large products, then the usual technology associated with the use of a conventional inverter is not suitable. The method under consideration is characterized by greater productivity.
3. A special feature of the technology is that it is used to connect materials of different chemical compositions.
4. After using explosion welding, it must be remembered that when the joint zone is reheated, intense diffusion may occur.
5. When exposed to high temperatures, the properties of the seam may disappear over time. At the same time, the strength and reliability indicator will decrease significantly.

Types of welding

When joining steel and titanium, vanadium and niobium can be used as a layer. Otherwise, over time, the joint will not withstand strong mechanical stress.

Don't forget about safety precautions. The blast wave carries with it a danger to the performer himself and those around him. When developing the method under consideration, we paid quite a lot of attention to safety precautions. Let's call its features the following points:

1. Landfills should be located away from residential facilities and populated areas. This is due to the fact that the blast wave can damage buildings.
2. A work platform is often created by using sand. The recommended thickness of the sand cushion is 1 meter. If the estimated impact force is 200 kilograms, then special preparation of the site is carried out.
3. When processing small products and applying a charge with an impact of 20 kilograms, an explosion chamber is used. A similar structure can be located in a factory or in a special room. The recommended wall thickness is 25 cm. In the manufacture of such a structure, materials are used that can withstand this kind of impact.
4. The operator must use special clothing and personal protective equipment. Particular attention is paid to fire safety, since an explosion can lead to a fire.

It is worth considering that the technology can only be carried out by persons who have received the appropriate permission.

Preparing for work

The quality of welded metals can be improved with careful preparation for the process. To carry out explosion welding you need:

1. A more suitable explosive for the case at hand.
2. A supporting foundation that must withstand strong impacts. Before starting work, you need to check the condition of the supporting foundation. Various defects can lead to the fact that the base will not withstand the impact.
3. Parts to be joined. They are pre-prepared. To do this, the surface layer can be removed with an abrasive material.
4. A detonator is required for an explosion.

It is worth considering that the features of the preparatory process largely depend on the type of materials being joined. Examples include the following:

1. Large parts.
2. Cylindrical parts.
3. Multilayer and fiber reinforced parts.

Welding range

Don't forget that a foundation slab can only withstand a few explosions. After this, it is destroyed and the site has to be prepared again.

Advantages and disadvantages of explosion welding

Like many other technologies, explosion welding has a fairly large number of positive and negative aspects. The advantages are:

1. High speed of processing of connected elements. As previously noted, it only takes a few fractions of a second to join the metal. However, it takes quite a lot of time to prepare the site and the materials themselves.
2. It is possible to obtain high-quality bimetal compounds. It is worth considering that other technologies do not allow combining materials with different physical and mechanical parameters.
3. The technology makes it possible to join materials that are characterized by a low degree of machinability.
4. You can create a product for further forging and stamping. Recently, forging and stamping have been carried out to harden the surface. A conventional seam is characterized by the fact that it cannot withstand variable loads.
5. You can get a product with complex corner shapes. An example is products with curves.

Explosion welding is considered a complex technological process, but it can be used to produce the most complex products. There are also several serious disadvantages:

1. Low degree of safety during an explosion. This is due to the fact that it is quite difficult to control the blast wave.
2. In order to provide the services in question, you need to undergo special training and obtain permission to do so. Failure to comply with the technology leads to the fact that the workpiece may be damaged.
3. Work can only be carried out if there is a special protective chamber or testing area.
4. It is almost impossible to automate the process in question. That is why it is necessary to carefully prepare for each process of joining products.

The above information determines that the positive aspects of explosion welding are much greater than the negative ones.

How does this happen

At its core, explosion welding refers to mechanical types of joining metals. The transformations that occur are as follows: as soon as the detonator is triggered, a gas is formed, resulting in the formation of chemical energy.

The operating principle of explosion welding.

It is converted into kinetic energy, which imparts speed to a metal workpiece when it comes into contact with another stationary workpiece. The peculiarity of the contact between the workpieces is that it does not occur along the area of ​​the workpieces, but along a line with a subsequent increase in the total contact surface.

Deformation of metals with the formation of a weld occurs due to the influence of kinetic energy. The key factor of the method is the speed that is transmitted to the moving part. If this speed does not reach the required level, the weld simply will not work.

Features of micro-inhomogeneity of welded joints

Chemical and physical microheterogeneity of welded joints manifests itself when using almost all types of welding. The features include several points:

1. Physical heterogeneity is detected using metallography. Due to this, the strength of the resulting structure is significantly reduced.
2. Chemical heterogeneity can also significantly reduce the quality of the connection.

That is why, when the connection zone is exposed to high temperatures, the strength and reliability coefficient can significantly decrease.

Compliance with quality standards and compliance testing

To assess the strength and homogeneity of a welded joint obtained by explosion, the following methods are used:

1. Ultrasonic flaw detection. The method is used to assess the strength of seams. The fluoroscopic method is used to check important connections.
2. The seam is cut or torn. Also used to evaluate strength.
3. Deflections and torsion of the connection. They help evaluate the ductility of the resulting structure.

If in doubt, a warp check is required. To do this, measure the thickness of the material in several places.

Influence of the initial state of the materials being welded

The initial condition of the products largely affects the quality of the connection. The condition of the seam may be affected by:

1. Presence or absence of contamination. In addition, corrosion on the surface can significantly reduce the quality of the connection.
2. The degree of manifestation of micro-irregularities. If the surface is characterized by strong waviness, then it is necessary to pre-level it.
3. Type of metals being joined. If necessary, it is possible to connect alloy alloys and carbon steels, non-ferrous metals.

Welding seam during explosion welding

The welding method under consideration is characterized by the fact that there is no need to prepare the surface for processing. This greatly simplifies the process and reduces costs.

For general information

In fact, despite the fancy name, explosion welding is quite easy. It is a subtype of pressure welding. Read on and learn the technology of this welding method.

Usually you need to connect two metal surfaces. The first is called immobile, while the other remains mobile, located on top, placed at an angle. Also, the fixed part is called the main part, and the second part is called the cladding part.

An explosive compound and a detonator are applied to the top, that is, to our moving part, which makes the top part move. Next, the moving part develops a decent speed and collides with the lower part.

The force of the impact deforms the parts, and thus they are welded into one element. But explosion welding is also suitable for decorative work because it makes a variety of joints. We can make composite products or duo metal.

Also, such products are well preserved and do not corrode; they withstand loads of weight and force well. I think few people have heard about this welding technology, but this does not prevent it from being used in many industrial areas.

From gas and oil processing to rolled metal. Explosion welding has even begun to become a separate type with its own types, which means there is a real demand for it in today's welding market.

Explosives for welding

There are quite a large number of different explosives that can be used in welding. Among the features of their choice, we note the following points:

1. Bulk substances are more popular, since their use can create a charge of the required shape and size.
2. Attention is also paid to the choice of detonator.

For each case, a substance is selected experimentally. In specialized stores you can find the required materials.

Difficulties of the explosive process

Explosion welding is characterized by quite a lot of difficulties. An example is the following information:

1. The main difficulty concerns the storage and use of explosives.
2. In the event of an explosion, the possibility of a blast wave affecting the environment cannot be excluded.
3. In order to eliminate the possibility of the procedure’s impact on the environment, welding should be carried out at special sites. However, they should be located away from industrial and residential areas.
4. If small products are being connected, special chambers can be used.
5. Joining dissimilar metals also leads to significant problems. An example is a decrease in strength.
6. To improve the quality of the connection, it is recommended to thoroughly prepare the surfaces to be joined. Cleaning is carried out until a metallic shine is obtained.
7. Another serious difficulty is calculating the required amount of explosive. In some cases, such parameters are tested experimentally.

Example of products obtained using explosion welding

It is quite difficult to provide the most favorable conditions for explosion welding.

general characteristics

Explosive welding is a type of welding technology that uses pressure. Using the kinetic energy of a part accelerated to high speed, plastic deformation of the contacting layers of metal on the required parts is performed.

To accelerate the part to the required speed of several hundred meters per second, explosion energy is used. For maximum effect, one part is accelerated, and the second is fixed in a stationary state. And at the moment of their contact, the required deformation is performed.

It is worth noting! In order for the necessary movement to occur, an explosive and a detonator are placed on the surface of the moving part. The explosive is initiated and an explosion occurs, which causes movement of the moving part.

Explosion welding makes it possible to obtain composite products; it can also be used to produce elements with a multi-level and bimetallic structure. The finished product will be highly resistant to corrosion and mechanical stress. This welding technology is used in various fields of production - in oil, engineering and many others.

Areas of use

The method in question is used extremely rarely. This is due to a large number of problems associated with preparing the site and storing explosives. Explosion welding is effective in the following cases:

1. When creating high-quality and reliable pipe joints.
2. When combining metals with different properties.
3. When obtaining monolithic products of complex shape.
4. When connecting metal structures of complex configuration.
5. When obtaining composite blanks that have a cylindrical shape.

In general, we can say that the technology is not used to produce conventional products. This is due to the high cost of the materials used and difficulties in preparing the site for the work.

In conclusion, we note that explosion welding should be carried out exclusively in compliance with safety precautions. Even the smallest errors can lead to product deformation and some other problems.

Efficiency Study

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