Explosion welding is a combination of elements by the method of directional energy explosion and belongs to the category of explosive metal processing.
Description
Work with this technique requires a specific arrangement of parts, in particular, the target element and the part to be processed are parallel or at a specified angle.
During the explosion movement, parts at high speed hit each other and form a welding joint, the reliability of which is achieved by deformation changes on the surface. Due to the high transience of the method, there is no bulk diffusion.
Explosion welding has become most widespread in the processing of dissimilar metals and alloys.
The main condition is a thorough preparatory work, which includes meticulous degreasing of the elements and cleaning, subsequently they go through welding to form a metallic luster.
Schemes
There are many different schemes of technological work. They are combined by the action of detonation products on the target and impact with other surfaces. All varieties of schemes are based on two initial ones, which have fundamental differences - these are parallel and angular.
All types of alloys and steel allow you to create bimetal, explosion welding in this case does not change the structural characteristics of the material and the initial dimensions of the products, so there is no need for additional verification of compliance with the available properties. Finished surfaces do not have wave-like defects and are subject to heat treatment only if there is voltage at the welding site. At the same time, production is characterized by a minimum amount of waste and a cost that does not change from the delivered lots and the grade of material.
Explosion welding: advantages and disadvantages
Metal processing has gained sufficient distribution due to the following positive aspects:
- the formation of reinforced composites;
- use for packages with many layers;
- welding of materials that are heterogeneous in relation to each other, for example, steel - titanium;
- low consumption;
- profitability.
Despite the many advantages, it was not without drawbacks, the main of which is a noticeable reproducible noise, which necessitates a sufficient distance from residential and public buildings, there is also the difficulty of storage and transportation, caused by the danger of an explosion.
Materials
Bulk explosives are used for work, including nitrate, ammonites, granulite and others. The mass of substances used in modern technological processes can vary from several hundred kilograms to one gram.
Explosion welding of metals is characterized by the release of energy, the main part of which enters the surrounding space in the form of shock waves, radiation in the form of seismic disturbances and fragments with a wide radius of spread is also possible.
The process should be carried out at a sufficient distance from residential buildings in specialized chambers and at landfills, this is caused by the presence of a shock wave - an inevitable factor with high danger and damaging effects.
What you need to know
The main feature is the ability to process metal surfaces of any kind. Selected compounds can have any size, which is an additional advantage. Explosion welding, the scheme of which is presented above, provides instant production of high-quality compounds, which are formed in less than a millionth of a second.
It is worth noting that if it is necessary to re-heat the finished surfaces, it should be remembered that there is a high risk of active diffusion, it may appear at the site of the previously obtained compound. Because of this, there is a high probability of a significant decrease in the strength and reliability characteristics, especially when exposed to a high temperature range.
To prevent such harmful changes in the connection process, special intermediate layers on a metal base are used, while the surfaces undergoing treatment and the used additives do not form chemical compounds. An example is welding of titanium and steel, in this case materials such as vanadium or tantalum are used as a special layer.
Conditions
Explosion welding technology resembles a pressure joint, common features are especially noticeable at some points in the technique.
The process should be carried out when certain conditions are created, without them the task becomes impossible. First of all, a high temperature range should be taken into account, it is necessary to reduce the time taken to complete the work. Surfaces to be treated must have plastic deformations. They should also be tightly connected to each other. Compliance with the requirements indicated above ensures a quality connection.
A missile plate, movable with respect to another, which remains stationary, at the time of impact has a specific amount of kinetic charge per unit of the processed plane.
If explosion welding is characterized by the simultaneous movement of elements, the characteristics of elasticity and reliability of the connection are reduced to minimum values.
Speed
The level of obtained properties that explosion welding provides is more dependent on the speed of the propelling process. At a low speed, there is practically no likelihood of a compound being formed, despite the full observance of other basic conditions.
It is worth noting that inappropriate contact speeds are not an obstacle to obtaining high-quality and reliable finished products, provided that a suitable throwing speed is calculated in advance. This parameter has a direct effect on the type of place to be joined, that is, the treated zone changes the characteristics of thermal concentration in accordance with the speed.
Calculations, as a rule, are experimental in nature, since in this area there is no established methodology for determining the modes. This is due to the fact that the theory of this technological process has not yet been created due to the impossibility of a complete study, and the complexity of preliminary determination of all the nuances of the behavior of metal surfaces and the blast wave. That is, each individual case requires the creation of a calculated mode and its own work methodology.
Performance study
The Autodyn program belongs to the category of universal type software designed to analyze processes characterized by high non-linearity and quick completion. They can be associated with the influence of fragments, shock waves and other damaging factors on personal protective equipment or with the characteristics of structural changes during the destructive action, for example, explosion welding. Autodyn thus allows a quick assessment of the effectiveness of defense systems and security methods used today without additional costs.