WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 1
The first task of this lesson is designed to assist you in
learning
the
processes
for
identifying
electrodes
by
classification, and intended uses; the automotive welding
processes, materials, and identification processes, and the
techniques of joint design as they pertain to electric arc
welding.
2.
Identification and Uses of Electrodes
a. General. During electric arc welding operations, when molten
metal is exposed to the atmosphere, it will absorb oxygen and
nitrogen from the air and will become brittle.
To protect it
from this damaging reaction, a slag cover over the molten or
solidifying metal must be provided.
This cover is made by
coating the electrode with a substance that will vaporize and
defuse in the arc stream to form a protective cover that will
stabilize the arc and protect the metal.
Because there are
several different types of metals used in Army equipment, it is
necessary to use the correct electrode whenever welding this
equipment.
The
following
subparagraphs
describe
the
classification of electrodes, their intended uses, and the
factors to be considered when selecting electrodes.
b. Factors in Selecting an Electrode. The purpose of selecting
the correct type electrode is to provide arc stability,
smoothness of the weld bead, easy slag removal, and minimum
spatter that are essential to top quality welding. Factors to be
considered when selecting electrodes are:
(1) Specific metal properties required in the weld such
as
corrosion resistance, ductility, or high tensile strength.
(2) Type of base metal to be welded.
(3) Position of the weld, such as flat or vertical.
(4) The type of electrical current that is available.
(5) Electric current polarity (straight or reverse) which is
available.
(6) Dimensions of the section to be welded.
(7) The type of fit that the work permits.
2
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