Metal Welding - Types and Processes
Welding. So you think it's as simple as grabbing the gun and pulling the trigger, eh? Tell me this then - what types of welding are there? Not completely sure? Read on... Arc Welding Arc welding is a process utilizing the concentrated heat of an electric arc to join metal by fusion of the parent metal and the addition of metal to joint usually provided by a consumable electrode. Either direct or alternating current may be used for the arc, depending upon the material to be welded and the electrode used. Electroslag Welding Electroslag Welding (ESW) deposits the weld metal into the weld cavity between the two plates to be joined. This space is enclosed by water cooled copper dams or shoes to prevent molten slag from running off. The weld metal is produced from a filler wire that forms an initial arc with the workpiece until a sufficient pool of liquid metal is formed to use the electrical resistance of the molten slag. This process requires special equipment used primarily for horizontal welds of very large plates up to 36 inches or more by welding them in one pass as in large machinery and nuclear reactor vessels.
There are also variations of ESW where shielding is provided by an appropriate gas and a continuous arc is used to provide weld metal. These are termed Electrogas Welding or EGW machines.
Fluxed-Core Arc-Welding Fluxed-Core Arc-Welding (FCAW) uses a tubular electrode filled with flux that is much less brittle than the coatings on SMAW electrodes while preserving most of its potential alloying benefits.
The emissive fluxes used shield the weld arc from surrounding air, or shielding gases are used and nonemissive fluxes are employed. The higher weld-metal deposition rate of FCAW over GMAW (Gas Metal Arc Welding) has led to its popularity in joining relatively heavy sections of 1" or thicker.
Another major advantage of FCAW is the ease with which specific weld-metal alloy chemistries can be developed. The...
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