Explosion welding, method operation diagram, application, technology

There is a huge diversity in metal joining technologies, which sometimes defies explanation. Thus, in 1961, explosion welding. This type of welding utilizes explosive energy. Various explosives are used, including granulite, granulotol, hexogen, ammonium nitrate, ammonal, and ammonites.

Explosive welding refers to a group of mechanical processes for joining metals in which the chemical energy of the explosive charge is converted into mechanical energy, imparting greater velocity to one of the parts being welded. When the moving part collides with the stationary part, kinetic energy is generated, which is used for plastic deformation of the metal layers being joined, resulting in the metal being welded.

Explosive welding diagram

Explosive welding diagram is produced as follows:

• the part to be welded, for example a metal plate, is placed on the base
• above it, a second part is placed on special technological supports, with some gap
• on the surface of the second part there is a charge of explosive, strictly selected according to the height and area, usually equal to the part
• a detonator is inserted into one end of the explosive
• then an explosion is triggered and the detonation wave front propagates at a speed of 2000-8000 m/s, determined by their physical state and chemical composition
• The gaseous products of the explosion retain the same volume of explosive for some time and are under a pressure of 100-200 thousand atm, and then at a certain speed they expand along the normal to the free surfaces of the charge, giving the area of metal underneath an impulse.

Further explosion welding diagram shows the physical and chemical processes of joining two metals.

Explosion welding process

After detonation continues explosion welding process, which grips the metal surfaces. A high-speed collision occurs between the upper metal plate and the stationary one with a pressure of 10²-10³kbar, which promotes compression with the most favorable conditions for plastic flow in the direction of welding. In this case, explosion welding process Surface contaminants and oxides on the metal surface are fragmented, dispersed, and removed by the cumulative effect. This is followed by the formation of strong metallic bonds in the solid phase. The activation energy for this phase is provided by the plastic deformation work caused by the heating.

The rapidity of explosion welding prevents volume diffusion from developing, despite the heating. This allows this type of welding to be widely used for joining dissimilar metals and alloys. Thus, explosion welding process It is mechanical, arising from chemical energy, and the high rate of heat propagation greatly heats the metal in the joint zone to high temperatures. Explosive welding is used for:

• production of bimetallic sheets of metals of any combination;
• production of hollow or solid composite blanks for profile rolling;
• for cladding machine parts.