Do you remember when you were in school in the art & craft class we used to join two pieces of paper with glue or through a stapler? Well here it is also the same, instead of joining two pieces of paper, we join two metal pieces not with glue or with stapler but with the scientific method of fabrication, where the metal pieces are fused together with heat and pressure and this process is called welding.
Welding is generally used for metals and thermoplastics but it can also be used on wood. Once the welding job is completed the welded joint can be referred to as a weldment. The metal pieces which are joined together are generally referred to as parent materials and the material which helps to join them is known as filler material or consumables.
Consumables are usually chosen according to the composition of the parent metals which helps in forming homogeneous welds and sometimes different filler materials are used with cast irons therefore the properties which are used in these kinds of welds are typically known as heterogeneous welds.
An interesting fact about welding is, the electric arc is low voltage & high current discharge, generally for SMAW/GTAW current ranges 400-500 AMPs &SAW 600-1000 Amps and normal voltage range 10v to 35v. Capabilities vary from 60 percent to 90 percent which depends on the type of welding process, the heat is lost by conduction through the base metal and the radiation of the external environment.
In the process of welding, heating at high temperatures causes a weld pool of molten material and when it gets cool it forms a joint that can be stronger than the parent material. The pressure is also used to produce a weld either alongside the heat or by itself. The welding process also needs protection from the external environment, hence there is a high chance that it can get contaminated or can get oxidized to protect the weld from these scenarios shield gases are used to protect the weld and helps to become stronger.