Welding joins two pieces of material, almost always metal, by melting the workpieces themselves, usually with a filler added, so that on cooling the join is a single continuous piece as strong as the base material, unlike a bolted or riveted joint that merely holds two separate pieces together. Blacksmiths forge-welded iron by hammering heated pieces together for millennia before anything like a modern process existed. The technology that made welding an industrial method arrived in the late nineteenth century: the Russian engineers Nikolai Benardos and Nikolai Slavyanov developed carbon-arc and metal-arc welding in the 1880s, and oxyacetylene welding followed soon after once cheap acetylene became available. Arc and gas welding steadily replaced riveting through the first half of the twentieth century, most visibly in shipbuilding, where an all-welded hull is both lighter and faster to build than a riveted one, though the welded Liberty ships of the Second World War also exposed brittle-fracture failures that taught the field hard lessons about weld metallurgy and quality control still built into welding codes today. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/
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Disputed
Origin YearForge welding, hammering heated metal pieces together without melting them, is attested from the Iron Age and is far older; the fusion welding this entry principally describes, joining metal by melting it, began with Nikolai Benardos carbon arc welding process in 1881, followed quickly by Elihu Thomson resistance welding in 1886. Core PrincipleFusing two pieces of material, usually metal, by melting the workpieces and typically adding a filler, so the finished join is continuous with, and as strong as, the base material. 1 FAQs
Why does a weld need shielding?
Shielding keeps air from contaminating or oxidizing the molten weld pool.
Molten metal reacts with the oxygen and nitrogen in the air, and the result is porosity and brittleness in the finished weld. Arc welding therefore uses shielding gas to keep atmospheric oxygen out of the molten weld pool. Some processes take the gas from cylinders of inert or semi-inert gas, while others use a flux coating on the electrode that breaks down to create the gas. Submerged arc welding instead strikes the arc beneath a covering layer of flux that blocks contaminants in the atmosphere. Because moving air can disturb a gas shield, shielded metal arc welding is the usual process for open-air work, where inert gas processes cannot readily be used.
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Annealing, Methods Welded joints are sometimes annealed afterward to relieve the thermal stress welding introduces.
In Field
Source Encyclopaedia BritannicaEncyclopaedia Britannica editors
Long-Form Articles
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1. Welding (Wikipedia)
Wikipedia contributors, Wikimedia FoundationHistory section
Two inventors from the Russian empire working in a French laboratory, Polish engineer Stanislaw Olszewski and de Meritens' pupil Nikolai Benardos, developed the first electric arc welding method, known as carbon arc welding using carbon electrodes, receiving a British patent in 1885 and an American patent in 1887. The advances in arc welding continued with the invention of metal electrodes in the late 1800s by a Russian, Nikolai Slavyanov (1888), and an American, C. L. Coffin (1890).
In Group: Casting, Forging and Machining Processes, Introduction
Welding is a fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperatures to melt the parts together and allow them to cool, causing fusion.
View the Source 2. A History of Technology
Charles Singer, E. J. Holmyard, A. R. Hall and Trevor I. Williams, editors, Oxford University Press, 1954View the Source Encyclopaedia Britannica
Encyclopaedia Britannica editors, Encyclopaedia Britannica, Inc.In Field: Mechanical EngineeringView the Source Reader Challenges (0)
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