Atomic hydrogen welding 3261380 206559215 2008-04-18T20:13:23Z Trojancowboy 4947829 correct failure to log in properly {{Redirect|AHW|the airline based in Kharkiv, Ukraine|Aeromist-Kharkiv}} '''[[Atomic hydrogen]] welding''' ('''AHW''') is an [[arc welding]] process that uses an arc between two metal [[tungsten]] [[electrode]]s in a shielding atmosphere of [[hydrogen]]. The process was invented by [[Irving Langmuir]] in the course of his studies of atomic hydrogen. The [[electric arc]] efficiently breaks up the hydrogen molecules, which later recombine with tremendous release of heat, reaching temperatures from 3400 to 4000 °C. An [[acetylene]] torch merely reaches 3300 °C. This is the third hottest flame after [[cyanogen]] at 4525 °C and [[dicyanacetylene]] at 4987 °C. This device may be called an '''atomic hydrogen torch''', '''nascent hydrogen torch''' or '''Langmuir torch'''. The process was also known as '''Arc-Atom welding'''. The heat produced by this torch is sufficient to melt and weld [[tungsten]] (3422 °C), the most [[refractory metal]]. The presense of hydrogen acts as a gas shield and protects metals from contamination by [[carbon]], [[nitrogen]], or [[oxygen]], which can severely damage the properties of many metals. It eliminates the need of [[Flux (metallurgy)|flux]] for this purpose. The arc is maintained independently of the workpiece or parts being welded. The hydrogen gas is normally diatomic (H<sub>2</sub>), but where the temperatures are over 600 °C (1100 °F) near the arc, the hydrogen breaks down into its atomic form, simultaneously absorbing a large amount of heat from the arc. When the hydrogen strikes a relatively cold surface (i.e., the weld zone), it recombines into its diatomic form and rapidly releases the stored heat. The energy in AHW can be varied easily by changing the distance between the arc stream and the workpiece surface. This process is being replaced by shielded metal-arc welding, mainly because of the availability of inexpensive inert gases. In atomic hydrogen welding, [[filler metal]] may or may not be used. In this process, the arc is maintained entirely independent of the work or parts being welded. The work is a part of the electrical [[circuit]] only to the extent that a portion of the arc comes in contact with the work, at which time a voltage exists between the work and each electrode. == References == * Welding Handbook Vol. 2 Library of Congress number 90-085465 copyright 1991 by American Welding Society * Kalpkjian, Serope and Steven R. Schmid. ''Manufacturing Engineering and Technology'' textbook Fifth edition. Upper Saddle River: Pearson Education, Inc., 2006 * {{Cite web | title = Atomic Hydrogen Welding | work = Specialty Welds | accessdate = 2008-01-26 | url = http://www.specialwelds.com/underwater-welding/atomic-hydrogen-welding.htm }} * {{Cite encyclopedia | title = Atomic - Hydrogen Welding | encyclopedia = Odhams Practical & Technical Encyclopaedia | accessdate = 2008-01-26 | date = 1947 | url = http://www.lateralscience.co.uk/AtomicH/AHW.html }} * {{Cite web | title = Atomic Hydrogen Blowtorch | work = Lateral Science | accessdate = 2008-01-26 | url = http://www.lateralscience.co.uk/AtomicH/atomicH.html }} * {{Cite web | last = Bearden | first = Tom | title = THE ATOMIC HYDROGEN REACTION | accessdate = 2008-01-26 | url = http://www.cheniere.org/misc/a_h%20reaction.htm }} {{Metalworking - Welding}} [[Category:Arc welding]] [[Category:Hydrogen technologies]] {{industry-stub}} [[de:Arcatom-Schweißen]]