“... embracing the fracture with a pair of hot tongs and closing so tight till the weld leans out..."
Vannoccio Biringuccio, sixteenth-century writer
Welding is the process of joining pieces of metal with heat, pressure, or a combination of both, so that they completely fuse together.
The first instance of welding is thought to have been in the smelting of iron ore to create wrought iron, some of the earliest evidence of which was discovered in a Hattic tomb in northern Anatolia, dated to around 2500 B.C.E. Lumps of the iron ore were heated in furnaces until the impurities melted into a slag, trapped in pores in the still solid iron. The hot piece was then hammered to expel the liquid slag and weld together the particles of surrounding iron.
Similar methods of heating and hammering were used to join separate pieces of iron, and examples of this were discovered in Tutankhamun's tomb of 1350 B.C.E. This type of forge welding remained the only known technique for centuries. One of the most renowned ancient examples is the Delhi Iron Pillar from the fourth or fifth century, which is a testament to the skill of the Indian metalworkers of the day.
Electricity paved the way for the development of arc welding and resistance welding, as well as the oxyacetylene torch. Welding flourished during the two world wars, and is still being developed to this day with the use of more challenging materials such as aluminum, and new technologies such as laser and electron beam welding.
