WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 2
Excessive dilution will cause the weld to be non-stainless,
brittle, and subject to cracking. Proper penetration will give a
long scalloped heat affected zone on each side of the weld as
shown in figure 32, view D, on the previous page.
Insufficient
penetration (surface fusion) will produce a fairly straight edged
heat affected zone on each side of the weld. This condition is
undesirable from the standpoint of good ballistic properties.
(7) Better control can be maintained of the heat input at the
joint and of the shape of the joint, by alternately depositing
the weld metal on one side of the joint and then the other. Each
layer of metal deposited serves to stress relieve the weld metal
immediately beneath it, and to partially temper the heat affected
zone produced in the base metal by the previous welding bead.
The passes at the toe of the weld joint, as shown in figure 32,
view C, also serve to anneal the base metal and are deposited
before the intermediate passes are added to fill the weld joint.
The annealing passes at the toe of the weld joint are an
important factor in the elimination of fusion zone cracks which
might start at the surface of the weld. Through careful control
of the depth of penetration, a heat affected zone with a
scalloped effect is produced.
c. Emergency Repairs.
Two methods of emergency repairs on
cracked armor plate that can be made by using butt straps are
shown in figure 33, views E and F, on the following page. These
straps are welded to the back of the cracked armor plate.
The
primary purpose of these butt straps is to strengthen the section
weakened by the crack.
d. Repairing Penetrations. Complete penetrations in homogeneous
armor plate are repaired by using the procedures shown in figures
34 through 36, on pages 79 through 81.
Figure 35, view A, on
page 80, shows that considerable structural damage has been done
to the metal immediately adjacent to the shell penetration.
Shell penetration holes smaller than the thickness of the armor
plate can be repaired by the butt strap method.
To effect
repairs, all torn and irregular edges of the damaged metal should
be removed to permit good contact between the butt strap and the
base armor
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