The mid-20th century: Advancements and World War II
Early advances in automatic welding
In 1920, P.O. Nobel of the General Electric Company invented automatic welding, which used bare electrode wire operated on direct current and arc voltage as the basis of regulating the feed rate. General Electric used automatic welding to build up worn motor shafts and crane wheels, while the automobile industry also used it to produce rear axle housings.
Development of welding electrodes
During the 1920s, various types of welding electrodes were developed, and a considerable controversy arose about the advantage of the heavy-coated rods versus light-coated rods. In 1927, Langstroth and Wunder of the A.O. Smith Company developed heavy-coated electrodes. Then in 1929, Lincoln Electric Company produced extruded electrode rods and sold them to the public. By 1930, covered electrodes were widely used. Welding codes appeared that required higher-quality weld metal, which increased the use of covered electrodes.
Innovations in gas shielding techniques
During the 1920s there was considerable research in shielding the arc and weld area using externally applied gases. The atmosphere of oxygen and nitrogen in contact with the molten weld metal caused brittle and sometimes porous welds. Researchers tested welds using gas shielding techniques, and Alexander and Langmuir did work in chambers using hydrogen as a welding atmosphere. They utilized two electrodes in their research, starting with carbon electrodes but later changing to tungsten electrodes. The hydrogen was changed to atomic hydrogen in the arc. It was then blown out of the arc forming an intensely hot flame of atomic hydrogen turning to the molecular form and liberating heat. This arc produced half again as much heat as an oxyacetylene flame. This became known as the atomic hydrogen welding process. Atomic hydrogen never became popular, but was used during the 1930s and 1940s for special applications of welding and later for welding tool steels.
H.M. Hobart and P.K. Devers were doing similar work with argon and helium. According to their 1926 patent applications, arc welding using gas supplied around the arc was a forerunner of the gas tungsten arc welding process (GTAW). They also showed welding with a concentric nozzle and with the electrode being fed as a wire through the nozzle. This was the forerunner of the gas metal arc welding process (GMAW).
Stud welding and submerged arc welding
Welders at the New York Navy Yard developed stud welding in 1930, specifically for attaching wood decking over a metal surface. Stud welding became popular in the shipbuilding and construction industries.
The automatic process that became popular was the submerged arc welding process. The National Tube Company developed this under powder, or smothered arc, welding process for a pipe mill at McKeesport, Pennsylvania. The company designed the process to make the longitudinal seams in the pipe. Robinoff patented the process in 1930 and later sold it to Linde Air Products Company. Linde renamed it to Unionmelt welding. Shipyards and ordnance factories used submerged arc welding during the defense buildup in 1938. Today, it remains one of the most productive and most popular welding processes.
Gas Tungsten Arc Welding (GTAW)
Gas tungsten arc welding (GTAW) had its beginnings in welding history from an idea by C.L. Coffin to weld in a nonoxidizing gas atmosphere, which he patented in 1890. H.M. Hobart and P.K. Devers further refined the concept in the late 1920s using helium and argon for shielding, respectively. This process was ideal for welding magnesium as well as stainless steel and aluminum. 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 gas tungsten arc welding process has become one of the most important.
Gas Metal Arc Welding (GMAW)
A turning point in welding history came when the Battelle Memorial Institute — under the sponsorship of the Air Reduction Company — successfully developed the gas metal arc welding (GMAW) process in 1948. This development used the gas shielded arc similar to the gas tungsten arc, but it replaced the tungsten electrode with a continuously fed electrode wire. One of the basic changes that made the process more usable was the small-diameter electrode wires and the constant-voltage power source. (H.E. Kennedy had patented this principle earlier.) The initial introduction of GMAW was for welding nonferrous metals. 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.