HISTORY:
Arc welding process was first design in England
in the year 1809, but it is succeed in 1912 in
U.S.A Strohmenger obtained patent on covered electrodes
and the first good welding joint was produced.
Since then a lot of changes and developments have
occurred as regards the constituents of flux coating
and core wire compositions. Covered electrodes
were commercialized in the year 1929.
DEFINITION: It is an arc welding
process where in coalescence is produced heating
the work piece with an electric arc set up between
a flux coated electrode and the work piece. The
flux covering decomposes due to arc heat and performs
many functions like arc stability weld metal protection
etc. The electrode itself melts and supplies the
necessary filler metal.
PRINCIPLE: Heat required for
welding is obtained from the arc struck between
a coated electrode and the work piece. The arc
temperature and thus the arc heat can be increased
or decreased by employing higher or lower arc
currents. A high current arc with a smaller arc
length produces a very intense heat. The arc melts
the electrode end and the job. Material droplets
are transferred from the electrode to the job,
through the arc, and are deposited along the joint
to be welded. The flux coating melts produces
a gaseous shield and slag to prevent atmospheric
contamination of the molten weld metal.
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