Mechanical Engineering


The process of joining two similar or dissimilar, metals or non-metals, with or without the application of heat, with or without adding a filler material is known as welding. The welding process can be divided into three types.

  1. Fusion welding: It is a process of joining two pieces of metals by application of heat. The two pieces to be weld are placed together, heated mostly with the addition of some filler material, brought to the melting temperature and solidify on cooling. Various solid phase welding processes are

(a). Oxy-acetylene welding

(b). Shield metal arc welding

(c). Submerged arc welding

(d). Gas tungsten arc welding

(e). Gas metal arc welding

(f). Electro slag welding

(g). Plasma arc welding

(h). Electron beam welding

(i). Laser beam welding

2. Solid phase welding: The two metals to be brought into contact to produce a metallic bond with or without the application of heat, but apply pressure for the plastic flow of the metals.

3. Plastic welding: It is a process in which two metals to be joined is heated to the plastic state and external pressure is applied without the addition of filler material. Forge welding, resistance welding and Thermit welding with pressure are the examples of the plastic welding.

There are mainly five types of welding joints.

(a). Butt joint  (b). Lap joint  (c). T-joint  (d). Corner joint  (e). Edge joint