Shielded metal arc welding is a manual arc welding process that uses a consumable electrode coated in flux to lay the weld. An electric current (either alternating current or direct current from a welding power supply) is used to form an electric arc between the electrode and the metals to be joined. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination. Because of the versatility of the process and the simplicity of its equipment and operation, shielded metal arc welding is one of world's most popular welding processes. It dominates other welding processes in the maintenance and repair industry, and though flux-cored arc welding is growing in popularity, it continues to be used extensively in the construction of steel structures and in industrial fabrication. The process is used primarily to weld iron and steels (including stainless steel), but nickel and copper alloys can also be welded. Read the rest of this article: http://en.wikipedia.org/wiki/Shielded_metal_arc_welding _______________________________ Today's selected anniversaries: 1249: Louis IX of France dispatched Andrew of Longjumeau as his ambassador to the Mongols. (http://en.wikipedia.org/wiki/Andrew_of_Longjumeau) 1804: Lt. Stephen Decatur led a raid to destroy the captured USS Philadelphia in Tripoli of the Barbary States, denying her use to the enemy in the First Barbary War. (http://en.wikipedia.org/wiki/Stephen_Decatur) 1857: Gallaudet University, the world's only university for hearing-impaired students, was established in Washington, D.C.. (http://en.wikipedia.org/wiki/Gallaudet_University) 1923: Howard Carter unsealed the burial chamber of Tutankhamun, a Pharaoh of the Eighteenth Dynasty of Egypt. (http://en.wikipedia.org/wiki/Howard_Carter) 1978: The first computer bulletin board system, CBBS, was established by Ward Christensen during a blizzard in Chicago, Illinois. (http://en.wikipedia.org/wiki/CBBS) _____________________ Wikiquote of the day: "Politics, as a practice, whatever its professions, has always been the systematic organization of hatreds." -- Henry Adams (http://en.wikiquote.org/wiki/Henry_Adams)