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This section covers more specifically
the actual welding of low-carbon mild steels, stainless steels,
aluminum alloys and copper alloys. It
is the purpose of this section to establish recommended general
welding procedures and conditions for
each material. The
tables of welding conditions should serve only as a starting point when beginning
new applications. They
do not represent the only good way in which a certain weld can be made. Changes
in the welding conditions
will most likely be caused by differences in the welders experience, the
exact nature of the weld configuration
(joint design) and the equipment in use. To obtain the optimum welding conditions
that best satisfy
the particular requirements of a new application, it is always advisable to conduct
qualifying tests prior
to production. However, this is the basic point set a good, stable welding
condition and it can most probably
be used for many applications. When
changes to the welding conditions are required, they must be carefully made. As
seen in the previous section,
each welding parameter has specific effects on the weld bead characteristics and
many do overlap. All
adjustments must be made one at a time and recorded for future reference.
The discussion accompanying these tables
will emphasize pertinent topics and establish general rules of
thumb. These rules should be
adhered to regardless of the welding procedure finally chosen. Each table
lists all the conditions necessary
to make a weld, based on the material thickness, joint design, and position
of welding. When referring to these
tables, there are several important points: 1.
The voltage listed is the arc voltage, not voltage read from a power source meter.
The arc voltage is read between
the last point of electrical contact in the torch (usually the guide tube) and
the workpiece. It is not the
voltage shown on the power source meter, which is generally 1.5 to 2.5 volts higher
depending on the size
and length of power cable. 2.
The weld size equals the material thickness in the case of fillet welds.
3. The joint designs depicted are not
the only designs that could be used for a given material thickness.