Tweco FABRICATOR 252i, Руководство по эксплуатации

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FABRICATOR 252i BASIC WELDING
BASIC WELDING 4-8 Manual 0-5155
Effects of Arc Welding Various Materials
A. High tensile and alloy steels
The two most prominent effects of welding these
steels are the formation of a hardened zone in the
weld area, and, if suitable precautions are not taken,
the occurrence in this zone of under-bead cracks
may result. Hardened zone and under-bead cracks in
the weld area may be reduced by using the correct
electrodes, preheating, using higher current settings,
using larger electrodes sizes, short runs for larger
electrode deposits or tempering in a furnace.
Hydrogen controlled Electrodes must be used for
this application.
B. Austenitic manganese steels
The effect on manganese steel of slow cooling from
high temperatures is to embrittle it. For this reason it
is absolutely essential to keep manganese steel cool
during welding by quenching after each weld or skip
welding to distribute the heat.
C. Cast Iron
Most types of cast iron, except white iron, are weld-
able. White iron, because of its extreme brittleness,
generally cracks when attempts are made to weld
it. Trouble may also be experienced when welding
white-heart malleable, due to the porosity caused by
gas held in this type of iron.
D. Copper and alloys
The most important factor is the high rate of heat
conductivity of copper, making preheating of heavy
sections necessary to give proper fusion of weld and
base metal.
Arc Welding Practice
The techniques used for arc welding are almost identical
regardless of what types of metals are being joined. Natu-
rally enough, different types of electrodes would be used
for different metals as described in the preceding section.
Welding Position
The electrodes dealt with in this publication can be used
in most positions, i.e. they are suitable for welding in
flat, horizontal, vertical and overhead positions. Numer-
ous applications call for welds to be made in positions
intermediate between these. Some of the common types
of welds are shown in Figures 4-12 through 4-19.
Art # A-07687
Figure 4-12: Flat Position, Down Hand Butt Weld
Art # A-07688
Figure 4-13: Flat Position, Gravity Fillet Weld
Art # A-07689
Figure 4-14: Horizontal Position, Butt Weld
Art # A-07690
Figure 4-15: Horizontal-Vertical (HV) Position
Art A-07691
Figure 4-16: Vertical Position, Butt Weld
Art # A-07692
Figure 4-17: Vertical Position, Fillet Weld