WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 2
tubular cutting electrode is made of mild steel.
of the metal is eliminated by the extremely high heat and oxygen
emitted by this process. This high heat and oxygen also oxidize
the rod and coating thereby preventing the rod metal from fusing
with the base metal.
(e) After completing the cut with an arc cutting process, the
rough edges and slag should be removed by hammering, chipping, or
grinding prior to welding.
5.
Welding Homogeneous Armor Plate
a. General.
Before welding damaged armor plate, the type of
armor must first be identified.
This identification can be
accomplished in the field by one of the methods described in
paragraph 2c on page 63.
Homogeneous armor plate can be
satisfactorily welded using the electric arc welding process and
18-8 stainless steel heavy coated electrodes with reverse
polarity. Armored vehicles that have been exposed to conditions
of extreme cold should not be welded until the base metal has
been preheated sufficiently to bring the temperature of the base
metal in the zone of welding up to no less than 100 F. At this
temperature, the metal will be noticeably warm to the touch. If
this preheat is not applied, cracking will occur in the deposited
weld metal.
b.
Procedure.
(1) Simple cracks as shown in figure 27, view A, on the
following page, should be flame cut into a beveled V joint as
shown in figure 27, view B, before welding. Care should be taken
to round off the corners at the toe and root of the joint. This
is necessary in order to eliminate excessive weld metal dilution.
The included angle of bevel, as shown in figure 27, view C,
should be approximately 45 degrees to provide electrode clearance
for making the root welding beads. The root opening, as shown in
figure 27, view D, should be from 3/16 to 5/16 inch, depending on
plate thickness.
(2) The weld
beads deposited at the root of the weld must be
good quality.
It is essential that care be taken to prevent
cracks, oxide
and slag inclusions, incomplete penetration, or
excessive weld
metal dilution in this area. Some of the methods
recommended as
preparatory steps for root
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