Welding - A 20th Century Hot Invention

Welding is the joining of two pieces of metal, in most cases, by heat. Some examples of welded products are ships, aircraft, railroad equipment, automobiles, machinery, pipelines, bridges, home appliances, electric and electronic parts, toys, and artwork.

Welding as we know it today is largely a development of the 20th century. Until then most welding was forge welding. In this process two pieces of iron were heated in a forge to white heat and then hammered together. But only iron and some kinds of steel could be fused together by forge welding. When better and stronger types of steel were developed, a more efficient method than forge welding was needed to join them. By the end of the 19th century new techniques of welding had been worked out.

Today there are about 40 different welding processes. The most important are classified under the general headings of arc welding, gas welding, resistance welding, and brazing.

Engineers have discovered that many metals can be welded together without applying much heat or pressure if the surfaces of the metals are very clean. These processes are called solid state processes because the metals fuse without melting. Another new type of welding is electron beam welding.

Metals like molybdenum and tungsten, which are very heat resistant and must be protected from the atmosphere, are placed in a vacuum chamber and fused by a concentrated beam of electrons. Even the energy of light is used in welding. A beam of concentrated light from a laser contains enough energy to melt steel. Laser beams are already being used to weld small parts, and wider use is being studied.

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