ESAB ET 220i AC/DC, Руководство по эксплуатации

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ET 220I AC/DC
Manual 0-5346 BASIC WELDING GUIDE
4-1
SECTION 4:
BASIC WELDING GUIDE
4.01 Stick (SMAW) Basic Welding Technique
Size of Electrode
The electrode size is determined by the thickness of metals being joined and can also be governed by the type of welding machine
available. Small welding machines will only provide sufficient current (amperage) to run the smaller size electrodes.
For thin sections, it is necessary to use smaller electrodes otherwise the arc may burn holes through the job. A little practice will soon
establish the most suitable electrode for a given application.
Storage of Electrodes
Always store electrodes in a dry place and in their original containers.
Electrode Polarity
Electrodes are generally connected to the ELECTRODE HOLDER with the Electrode Holder connected positive polarity. The WORK LEAD
is connected negative polarity and is connected to the work piece. If in doubt consult the electrode data sheet or your nearest Accred-
ited ESAB Distributor.
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 pre-
cautions 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 weldable. White iron, because of its extreme brittleness, generally cracks when at-
tempts 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. Naturally enough, differ-
ent 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. Numerous applications call for welds to be made in positions intermediate between these. Some of the com-
mon types of welds are shown in Figures 4-5 through 4-12.
Art # A-07687
Figure 4-1: Flat Position, Down Hand Butt Weld