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Welding History
The history of joining metals goes back several millennia, but before the end
of the 19th century, the only process available was
forge welding, where
blacksmiths pounded heated metal repeatedly until bonding occurred. The
Greeks of
the first millennium B.C. knew how to heat treat steel, and it is other ancient
peoples also knew basic welding principles. Forge welding developed extensively
during the first half of the 2nd millennium AD, and in 1540, Vannoccio
Biringuccio published De la pirotechnia, which includes descriptions of
the forging operation. Craftsmen of the Renaissance era were skilled in the
process, and the industry continued to grow during the following centuries.
However, with the discovery of the
electric arc by Sir Humphrey Davy in 1801, and subsequent developments
during that century, arc welding became the most commonly used method of
metallurgically joining metals.
In 1865, an Englishman named Wilde was granted a patent for his process of melting pieces of iron together. The electric arc did not make inroads into practical usage until 1881, with the introduction of carbon-arc street lamps. During that decade, many developments were made in the arc welding process, including the use of a metal electrode (instead of carbon) and of an insulated handle that permitted manual operation (patented by Russian scientist Nikolas de Benardos in 1887). Additionally, two other welding process were developed during the last two decades of the 19th century, namely resistance welding (a group of welding processes that produce coalescence of the faying surfaces with the heat obtained from resistance of the workpieces to the flow of the welding current in a circuit of which the workpieces are part, and by the application of pressure) and oxyacetylene welding. Oxyacetylene welding at first was more popular because of its portability and relatively low cost, but as the 20th century progressed, it fell out of favor for industrial applications. It was largely replaced with arc welding, as metal coverings for the electrode that stabilize the arc and shield the base material from impurities were developed, commonly known as flux.
World War I caused a major surge in the use of welding processes, with the various military powers attempting to determine which of the several new welding processes would be best. The British primarily used arc-welding, even constructing a ship, the Fulagar, with an entirely welded hull. The Americans were more hesitant, but began to recognize the benefits of arc welding when the process allowed them to repair their ships quickly after a German attack in the New York Harbor at the beginning of the war. Arc welding was first applied to aircraft during the war as well, as some German airplane fuselages were constructed using the process.
During the 1920s, welding applications began slowly increasing. The application of coverings for the metal electrodes became much cheaper in 1927 when an extrusion process was developed, and this fed major expansion in the role of arc welding during the 1930s and during World War II. Major advancements in the use of automatic welding, AC current and flux types were made during those years, and inert gases began to be used to allow the welding of reactive metals like aluminum and magnesium. This led to the creation of two commonly used processes, gas tungsten arc welding (then known as tungsten inert gas welding) and plasma arc welding.
The limitations of gas tungsten arc welding included the inability to weld thick sections, and this led to the development of a consumable electrode and ultimately gas metal arc welding, announced in 1948. During this time, several important developments were made, such as the use of iron powder in electrode coverings, the use of argon-helium inert gas mixtures, and ultimately, the much cheaper use of carbon dioxide as an often satisfactory replacement for argon and helium.
In 1958, the flux-cored arc welding process debuted, in which the self-shielded wire electrode could be used with automatic equipment, resulting in greatly increased welding speeds.
Further developments in welding have continued, but new processes (such as laser beam welding and electron beam welding) generally are designed for specialized applications. Research also has shifted toward assuring that individual welds for particular applications meet specifications.
Licensed under the GNU Free Documentation License. Material from the Wikipedia article "Welding". This article is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
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