Tweco 161 S Inverter Arc Welder - Manual (Page 29)

OPERATION THERMAL ARC 161 S
Manual 0-5199 4-3 Operation
4.03 STICK (SMAW) Electrode Polarity
Stick electrodes are generally connected to the "+" Posi-
tive Output Terminal and the work lead to the "−" Nega-
tive Output Terminal but if in doubt consult the electrode
manufacturers literature for further information.
4.04 Effects of Stick Welding Various
Materials
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. Hardened zone and
under-bead cracks in the weld area may be reduced by
using the correct electrodes, preheating, using higher cur-
rent settings, using larger electrodes sizes, short runs for
larger electrode deposits or tempering in a furnace.
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.
Cast Iron
Most types of cast iron, except white iron, are weldable.
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.
Copper and Alloys
The most important factor is the high rate of heat con-
ductivity of copper, making pre-heating of heavy sections
necessary to give proper fusion of weld and base metal.
Types of Electrodes
Arc Welding electrodes are classified into a number of
groups depending on their applications. There are a
great number of electrodes used for specialized industrial
purposes which are not of particular interest for everyday
general work. These include some low hydrogen types
for high tensile steel, cellulose types for welding large
diameter pipes, etc The range of electrodes dealt with in
this publication will cover the vast majority of applications
likely to be encountered; are all easy to use.
Metal Being Joined Electrode Comments
Mild Steel E6011 This electrode is used for all-position welding or for welding on
rusty, dirty, less-than-new metal. It has a deep, penetrating arc
and is often the first choice for repair or maintenance work.
Mild Steel E6013 This all-position, electrode is used for welding clean, new sheet
metal. Its soft arc has minimal spatter, moderate penetration and
an easy-to-clean slag.
Mild Steel E7014 All positional, ease to use electrode for use on thicker steel than
E6013. Especially suitable sheet metal lap joints and fillet welds,
general purpose plate welding.
Mild Steel E7018 A low-hydrogen, all-position electrode used when quality is an
issue or for hard-to-weld metals. It has the capability of producing
more uniform weld metal, which has better impact properties at
low temperatures.
Cast Iron ENi-Cl Suitable for joining all cast irons except white cast iron.
Stainless Steel E318L-16 High corrosion resistances. Ideal for dairy work etc.