**2. Working principle of explosive welding**

In the explosive welding process, the explosive is used as a source of energy to accelerate one of the metal plates into another. **Figure 1a** shows the initial set-up of the explosive welding process showing the two plates i.e. base plate which is kept stationary and the movable flyer plate is kept at a particular calculated distance called stand-off distance. The explosive box is placed with a buffer sheet over the plates. This buffer sheet protects the flyer plate from damage due to explosion. To initiate the main explosive detonator is used, which is placed above explosive. **Figure 1b** shows the schematic diagram after the detonation of explosive has initiated in the explosive welding process. Here we can observe the collision point, where the two plates collide and the bond formation occurs. Along with this jetting phenomenon is witnessed which is one of the most important criteria and also an essential condition for bond formation. Jetting occurs during an oblique collision at the collision point, in which it cleans the mating surfaces and Leaves behind a virgin surface free from oxide layers and contaminants. This helps to interact two mating materials at the atomic level when subjected to high impact pressure waves arising from the explosion effects. This process is capable of joining large surface area due to its ability to distribute high energy density. Explosive welding can be basically

#### **Figure 1.**

*Schematic diagram of explosive welding process in parallel set-up, a) initial set-up, b) after the explosion has initiated.*

**27**

**Figure 2.**

*initiated.*

*Explosive Welding Process to Clad Materials with Dissimilar Metallurgical Properties*

defined in two steps; first jet phenomenon occurs and cleans up the oxide layers and second, the high impact pressure forces the mating surfaces into such intimate contact that they meet at the interatomic level and results in strong metallurgical

In explosive welding process due to detonation effect of explosive many critical phenomena occur such as release of large gas product i.e. explosion, high impact collision between mating surfaces, high temperature, generation of heat, plastic deformation in the metal plates, pressure generation, jetting and bonding occurs for a very short period of time i.e. microseconds [19–21]. Out of these, plastic deformation that occurs at the weld interface due to high impact pressure is considered as one of the important factor responsible for good bond formation. Pastic deformation in explosive welding process occurs when pressure at the collision front overcomes the yield strength of the materials. Through plastic deformation an intimate contact is formed where the two mating surfaces are brought too close together that atomic reaction occurs between the mating surfaces [22–24]. Plastic deformation can be examined using visioplastic methods without disturbing the original properties of materials. The most distinctive form of plastic deformation is the wave formation in explosive welding [25]. Occurrence of high plastic deformation of the mating surfaces lead to grain refinement [26]. Difference in grain size adjacent to weld interface is observed due to severe plastic deformation [27]. Various researchers have witnessed high hardness value at the weld interface of explosively welded specimens in microhardness examination study. It was mainly attributed to intense plastic deformation developed across the weld interface. The level of plastic deformation in explosively welded specimens decrease gradually with increase in distance from

There are two types of explosive welding set-up i.e. parallel and the inclined set-up [31]. **Figure 1** shows the parallel set-up where the two plates are placed parallel to each other. This kind of configuration is used for joining large and thick plates. While the inclined set-up is shown in **Figure 2** in which flyer plates are inclined at a particular angle (α). This kind of configuration is generally applied

*Schematic diagram of explosive welding process in inclined set-up a) initial set-up, b) after the explosion has* 

*DOI: http://dx.doi.org/10.5772/intechopen.94448*

the weld interface [28–30].

**2.2 Types of experimental set-up**

for joining small and thin plates.

**2.1 Plastic deformation in explosive welding process**

bond.

defined in two steps; first jet phenomenon occurs and cleans up the oxide layers and second, the high impact pressure forces the mating surfaces into such intimate contact that they meet at the interatomic level and results in strong metallurgical bond.
