Tweco 95 S Thermal Arc(Jan2013) - Manual (Page 28)

THERMAL ARC 95 S OPERATION
Manual 0-5086 4-2 Operation
4.02 SMAW Electrode Polarity
Stick electrodes are generally connected to the "+" Positive
Output Terminal and the work lead to the "−" Negative
Output Terminal but if in doubt consult the electrode
manufacturers literature for further information.
4.03 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
current 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
conductivity 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 6013
Ideal electrodes for all general purpose work, features
include outstanding operator appeal, easy arc starting,
and low spatter.
Mild Steel 7014
All positional eletrode for use on mild and galvanized
steel furniture, plates, fences, gates, piples and tanks,
etc. Especially suitable for vertical-down welding.
Cast Iron 99% Nickel Suitable for joining all cast irons except white cast iron.
Stainless Steel 318L-16 High corrosion resistances. Ideal for dairy work etc.
Copper, Bronze, Etc.
Bronze
5.7 ERCUSI-A
Easy to use electrode for marine fittings, water taps and
valves, water through floats arms, etc. Also for joining
copper to steel and for bronze overlays on steel shafts.
Copper, Bronze, Dissimilar Metals,
Crack Resistance, All Hard-to
Weld Jobs
312-16
It will weld most problematic jobs such as springs,
shafts, broken joins, mild steel to stainless and alloy
steels. Not suitable for aluminum.