**2.2 Types of experimental set-up**

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 for joining small and thin plates.

#### **Figure 2.**

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

### **2.3 Terminology used in explosive welding**

**Base plate:** It is the one which is placed at the open ground or at the anvil. This is kept stationary and is the one on which the cladding is performed. Both the base plate and the flyer plate are cleaned thoroughly and polished gently before welding.

**Flyer plate:** It is the one which is placed above the base plate and during collision this plate hits onto the base plate. The selection of flyer plate and base plate is done on the basis of mass per unit area, whoever is less is placed as flyer plate. As compared to base plate it has the lowest density as well as tensile strength.

**Stand-off distance:** It is the one which maintains the distance between the flyer plate and the base plate. Stand-off distance helps the flyer plate to accelerate and acquire the required impact velocity to generate jetting. Apart from this, it also provides the exit path to the jet and the air formed between the flyer and base plate during the collision. In general stand-off distance is kept half or equal to the thickness of flyer plate.

**Buffer sheet:** This sheet is placed over the flyer plate. It is made up of rubber or PVC. The main role of this sheet is to protect the flyer plate from damage which can occur during collision due to explosion effects.

**Explosive box:** It is placed over the metal plates to be welded. This acts as a source of energy which provides the required forces to weld the materials. Explosive can be used as powder, slurry or sheet form which is spread over the buffer sheet uniformly.

**Detonator:** This is placed at the top of the explosive box. The main function of the detonator is to help in initiating the main explosive. The detonator is detonated with the help of dynamo placed at some distance from the trial site.
