Gas welding using oxygen and hydrogen dates back to the 1850s but the flame is virtually useless for welding steel. Gas welding had to await the discovery of the oxy-acetylene flame and a way to make acetylene at reasonable cost. Edmund Davy a famous British chemist is considered the first man to make acetylene. In 1836 attempting to make potassium he produced a black compound (potassium carbide) which reacted with water to produce a gas which burned with great brilliancy. He thought it would make an excellent illuminating gas but could not be made at moderate cost.Calcium carbide was not made and identified until 1862, again the process did not offer economic possibilities. Calcium carbide was undoubtedly accidentally produced in electric furnace operations before 1892, not until that year was it produced and identified both in France and the U.S. The experimenters were trying to make something else, only the Americans realised the potential commercial value. Major J.Turner Morehead and Thomas L.Wilson using an electric furnace were attempting to make calcium from quicklime and coal tar. The product of their electric furnace run was a dark crystalline mass which reacted violently with water. They had found a way to make acetylene economically and were not slow to recognise the value of their discovery. Because they sent a sample to Lord Kelvin in England together with details of the method by 1895 calcium carbide plants were operating in both England and France, as well as in the U.S. Plants in Norway and Switzerland followed close behind.All the acetylene made from calcium carbide during the first few years was used for lighting, house lamps, miner’s lamps and car lamps. In 1895, however, a French chemist, Henry Le Chatelier announced to the world that combustion of equal quantities of acetylene and oxygen produced a flame far hotter (3300 degrees C) than any gas flame previously known. He pointed out that the flame did not oxidise the metals which it melted. Experimenters went to work to find a way of controlling the flame for welding purposes. Credit for producing the first torch is generally given to Edmond Fouche, of France, who had already discovered a safe way to compress acetylene into cylinders. In 1903, Fouche sent one of his first torches to the U.S., where it was used with success that same year. The process of making acetylene from calcium carbide is still used to make most of our acetylene today.Dr.Carl Von Linde of Germany built his first plant for producing liquid air in 1895. In 1902 he built a plant which liquefied air and then fractionated it to produce pure oxygen. With acetylene already widely available the basic resources for the exploitation of the oxy-acetylene processes were now available. In 1907 the first U.S. plant to use the Linde process was started in Buffalo. Several plants which made oxygen by electrolysis were started up in the 1907-1912 period but by 1914 the ‘liquid air’ process was recognised as the way to produce high-purity oxygen. High purity is particularly necessary for cutting operations.Oxygen cutting was demonstrated at the Seattle World’s Fair, shortly after the century opened, but commercially useful torches were not available for several years. In 1907 Eugene Bournonville, one of the outstanding figures in the development of the oxy-acetylene processes in the U.S., showed the U.S. Navy Yard in Brooklyn that 14 inch portholes in armour plate 2-3 inches thick could be cut in 12 minutes. Previously it had taken two kerosene torch operators and five chippers 10 days to cut one porthole. Later in 1907 American-made cutting torches were used in the demolition of the old Grand Central Station in New York at one twentieth of the cost that older methods would have entailed. The next year three men with cutting torches cut out four 70 ton structural steel shields which had been used in the construction of railway tunnels under the Hudson River a job which would otherwise have required 20 workmen.In 1910 a 9000 ft pipeline built to bring water down to hydroelectric generators from a natural reservoir in Colorado, began to leak so badly, only months after entering service that a repair was essential. The pipe diameter was about 4 feet, with walls more than an inch thick at the lower end, where the internal pressure was 825 psi. Butt joints had been held together by riveted steel straps both inside and outside. A half-million dollar investment was in jeopardy. Welders repaired 200 joints successfully, using acetylene generated on the spot from 18 tons of calcium carbide and fed to torches through lines as long as 500 feet. Oxygen was produced from 23 tons of potassium perchlorate in two stationary plants and then compressed into cylinders.During the years 1912-1917 the oxy-acetylene processes really came into their own. Five manufacturers were using cutting and welding in the building of all-steel railway cars, and railway shops were using cutting and welding for manufacturing and repair purposes. Oxygen and acetylene plants by the score were in operation. The rapid expansion in steel output required during World War I would never have been achieved if the oxygen cutting torch had not made possible the cutting up of thousands of tons of scrap steel.Long before the first basic oxygen steel converter went into service steel mills consumed thousands of tons of oxygen removing surface defects from blooms, billets and slabs prior to rolling the steel to final plate or sheet form. These processes can be traced back to early use of oxy-acetylene cutting torches which were slightly modified so that they could groove steel rather than cut it.
Wednesday, 14 May 2008
Wednesday, 30 April 2008
Part 2 Electric Arc Welding up to 1960
Production of an arc between two carbon electrodes using a battery is credited to Sir Humphrey Davy in 1800. In the mid-nineteenth century the electric generator was invented and arc lighting became popular. Auguste De Meritens, working in the Cabot Laboratory in France, used the heat of an arc for joining lead plates for storage batteries in 1881. His pupil a Russian Nikolai Bernado with co-worker Stanislaus Olszewski secured a British patent in 1885 and an American patent in 1887. The patents show an early electrode holder and were the beginning of carbon arc welding which became popular during the late 1890s and early 1900s. Bernado’s efforts were restricted to carbon arc welding although he was able to weld iron as well as lead.
In 1890 C.L.Coffin of Detroit was awarded the first U.S. patent for an arc welding process using a metal electrode. This was the first record of the metal melted from the electrode carried across the arc to deposit filler metal in the joint to make a weld. Around 1900 Strohmenger introduced a coated metal electrode in the U.K., this was a thin coating of clay or lime but it provided a more stable arc. Oscar Kjellberg of Sweden invented a coated electrode during the period 1907-1914. Electrodes were produced by dipping short lengths of bare iron wire in thick mixtures of carbonates and silicates and allowing the coating to dry.
During the 1920s there was considerable controversy about the advantage of the heavy-coated rods versus the light-coated rods. The heavy-coated electrodes, made by extruding, were developed by Langstroth and Wunder of the A.O.Smith company and used by that company in 1927. In 1929 the Lincoln Electric Company produced extruded electrode rods that were sold to the public. By 1930 welding codes appeared which required higher-quality weld metal which increased the use of covered electrodes.
Also during the 1920s there was considerable research in shielding the arc and weld area by externally applied gases. The atmosphere of oxygen and nitrogen in contact with the molten weld metal caused brittle and sometimes porous welds. Alexander and Langmuir did work using hydrogen as a welding atmosphere developing the atomic hydrogen welding process which never became popular but was used during the 1930s and 1940s for special applications and later on for welding of tool steels. Hobart and Devers were doing similar work but using atmospheres of argon and helium.
Gas tungsten arc welding had its beginnings from an idea by C.L.Coffin to weld in a non-oxidizing gas atmosphere which he patented in 1890. The concept was refined in the late 1920s by Hobart who used helium for shielding and Devers who used argon. The process was ideal for welding magnesium, stainless steel and aluminium. It was perfected in 1941, patented by Meredith, and named Heliarc welding. It was later licensed to Linde Air Products, where the water-cooled torch was developed. The process patented by Meredith is now known as TIG welding, he was working at the Northrop Aircraft Company in 1939-1941 where Jack Northrop’s dream was to build a magnesium airframe for lighter, faster warplanes. The Linde Division of Union Carbide developed a number of torches for different applications sold under the brand name Heliarc. Linde also developed procedures for using argon which was more readily available and less expensive than helium.
The gas shielded metal arc welding process was successfully developed at Battelle Memorial Institute in 1948 under the sponsorship of the Air Reduction Company. This development used a gas shielded arc but replaced the tungsten electrode with a continuously fed electrode wire. The changes that made the process more usable were the small diameter wires and the constant-voltage source. The initial introduction was for welding nonferrous metals but the high deposition rate led users to try the process on steel. The cost of inert gas was relatively high and the cost savings were not immediately available. One of the key inventors of this MIG process was Glen Gibson who had been working on TIG welding in the development lab at Airco at the time. He indicates that although he went on to be the owner of a very successful business,”the greatest single day in his life was the day Steve (Steve Sullivan worked with Glen at the lab) and I cranked up the first (MIG) welding gun.”
In 1953, Lyubavskii and Novoshilov announced the use of welding with consumable electrodes in an atmosphere of carbon dioxide gas. The process gained favour as it used equipment developed for inert gas metal arc welding which could now be used for economically welding steels. A development was the short circuit arc and dip transfer which allowed all-position welding on thin materials.
Another variation was the use of inert gas with small amounts of oxygen which provided a spray-type arc transfer which became popular in the early 1960s. Soon after the introduction of carbon dioxide welding a ‘Dualshield’ process was developed using the gas produced by a flux core in addition to the normal shielding gas. This process, invented by Bernard, was announced in 1954 and patented in 1957, when the National Cylinder Gas Company introduced it. In 1959 a flux cored electrode which did not require external gas shielding was developed. This process named ‘Innershield’ gained popularity for non-critical work.
Robert F. Gage invented plasma arc welding in 1957. This process uses a constricted arc or an arc through an orifice, which creates an arc plasma that has a higher temperature than the tungsten arc. It is also used for metal spraying and has become the process of choice for thermal cutting.
Submerged arc welding, invented in 1930, is a common arc welding process. It requires a continuously fed consumable solid or flux cored electrode. The molten weld and the arc zone are protected from atmospheric contamination by being submerged under a blanket of granular fusible flux. When molten the flux becomes conductive and provides a current path between the electrode and the work. Submerged arc welding is normally an automatic or mechanised process, however, semi-automatic, hand held welding guns are available. Deposition rates approaching 45 kilograms per hour have been reported compared to 5 kilograms per hour maximum for shielded metal arc welding. Submerged arc welding is normally limited to ferrous metals and some nickel based alloys, also it is limited to long straight seams or rotated pipes or vessels. The process was invented by Jones, Kennedy and Rothermund, the patent was filed in October 1935, and assigned to Union Carbide Corporation. The following is taken from an article written in The Welding Journal. The importance of welding was emphasized early in the war when President Roosevelt sent a letter to Prime Minister Winston Churchill, who is said to have read it aloud in Parliament. The letter read in part, ”Here there has been developed a welding technique (referring to Submerged Arc Welding) which enables us to construct standard merchant ships with a speed unequalled in the history of merchant shipping.”
In 1890 C.L.Coffin of Detroit was awarded the first U.S. patent for an arc welding process using a metal electrode. This was the first record of the metal melted from the electrode carried across the arc to deposit filler metal in the joint to make a weld. Around 1900 Strohmenger introduced a coated metal electrode in the U.K., this was a thin coating of clay or lime but it provided a more stable arc. Oscar Kjellberg of Sweden invented a coated electrode during the period 1907-1914. Electrodes were produced by dipping short lengths of bare iron wire in thick mixtures of carbonates and silicates and allowing the coating to dry.
During the 1920s there was considerable controversy about the advantage of the heavy-coated rods versus the light-coated rods. The heavy-coated electrodes, made by extruding, were developed by Langstroth and Wunder of the A.O.Smith company and used by that company in 1927. In 1929 the Lincoln Electric Company produced extruded electrode rods that were sold to the public. By 1930 welding codes appeared which required higher-quality weld metal which increased the use of covered electrodes.
Also during the 1920s there was considerable research in shielding the arc and weld area by externally applied gases. The atmosphere of oxygen and nitrogen in contact with the molten weld metal caused brittle and sometimes porous welds. Alexander and Langmuir did work using hydrogen as a welding atmosphere developing the atomic hydrogen welding process which never became popular but was used during the 1930s and 1940s for special applications and later on for welding of tool steels. Hobart and Devers were doing similar work but using atmospheres of argon and helium.
Gas tungsten arc welding had its beginnings from an idea by C.L.Coffin to weld in a non-oxidizing gas atmosphere which he patented in 1890. The concept was refined in the late 1920s by Hobart who used helium for shielding and Devers who used argon. The process was ideal for welding magnesium, stainless steel and aluminium. It was perfected in 1941, patented by Meredith, and named Heliarc welding. It was later licensed to Linde Air Products, where the water-cooled torch was developed. The process patented by Meredith is now known as TIG welding, he was working at the Northrop Aircraft Company in 1939-1941 where Jack Northrop’s dream was to build a magnesium airframe for lighter, faster warplanes. The Linde Division of Union Carbide developed a number of torches for different applications sold under the brand name Heliarc. Linde also developed procedures for using argon which was more readily available and less expensive than helium.
The gas shielded metal arc welding process was successfully developed at Battelle Memorial Institute in 1948 under the sponsorship of the Air Reduction Company. This development used a gas shielded arc but replaced the tungsten electrode with a continuously fed electrode wire. The changes that made the process more usable were the small diameter wires and the constant-voltage source. The initial introduction was for welding nonferrous metals but the high deposition rate led users to try the process on steel. The cost of inert gas was relatively high and the cost savings were not immediately available. One of the key inventors of this MIG process was Glen Gibson who had been working on TIG welding in the development lab at Airco at the time. He indicates that although he went on to be the owner of a very successful business,”the greatest single day in his life was the day Steve (Steve Sullivan worked with Glen at the lab) and I cranked up the first (MIG) welding gun.”
In 1953, Lyubavskii and Novoshilov announced the use of welding with consumable electrodes in an atmosphere of carbon dioxide gas. The process gained favour as it used equipment developed for inert gas metal arc welding which could now be used for economically welding steels. A development was the short circuit arc and dip transfer which allowed all-position welding on thin materials.
Another variation was the use of inert gas with small amounts of oxygen which provided a spray-type arc transfer which became popular in the early 1960s. Soon after the introduction of carbon dioxide welding a ‘Dualshield’ process was developed using the gas produced by a flux core in addition to the normal shielding gas. This process, invented by Bernard, was announced in 1954 and patented in 1957, when the National Cylinder Gas Company introduced it. In 1959 a flux cored electrode which did not require external gas shielding was developed. This process named ‘Innershield’ gained popularity for non-critical work.
Robert F. Gage invented plasma arc welding in 1957. This process uses a constricted arc or an arc through an orifice, which creates an arc plasma that has a higher temperature than the tungsten arc. It is also used for metal spraying and has become the process of choice for thermal cutting.
Submerged arc welding, invented in 1930, is a common arc welding process. It requires a continuously fed consumable solid or flux cored electrode. The molten weld and the arc zone are protected from atmospheric contamination by being submerged under a blanket of granular fusible flux. When molten the flux becomes conductive and provides a current path between the electrode and the work. Submerged arc welding is normally an automatic or mechanised process, however, semi-automatic, hand held welding guns are available. Deposition rates approaching 45 kilograms per hour have been reported compared to 5 kilograms per hour maximum for shielded metal arc welding. Submerged arc welding is normally limited to ferrous metals and some nickel based alloys, also it is limited to long straight seams or rotated pipes or vessels. The process was invented by Jones, Kennedy and Rothermund, the patent was filed in October 1935, and assigned to Union Carbide Corporation. The following is taken from an article written in The Welding Journal. The importance of welding was emphasized early in the war when President Roosevelt sent a letter to Prime Minister Winston Churchill, who is said to have read it aloud in Parliament. The letter read in part, ”Here there has been developed a welding technique (referring to Submerged Arc Welding) which enables us to construct standard merchant ships with a speed unequalled in the history of merchant shipping.”
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