The technique of joining metal pieces by welding apparently originated more than 1500 years ago, when men learnt the art of heating two iron pieces to a dull red colour and then hammering them together to fuse them known as forged welding. Welding received special impetus during World War II for the mass production of industrial items and war equipment. Today, there are more than hundred welding processes that enable engineers to join almost all commercial metals and alloys in many sizes and thickness ranging from a fraction of a millimetre to more than 500 mm. In the last few years, many of the high temperature alloys have been fabricated by welding together critical components like in the case of guided missiles, jet aircraft and nuclear power plants. These developments would not have been possible without the use of welding.