Tweco 400i Transmig - Manual (Page 38)

TRANSMIG 400 i
5-4 July 18, 2008
5.02 Basic STICK Welding Guide
5.02.1 Electrode Polarity
Stick electrodes are generally connected to the
'+' terminal and the work lead to the '-' terminal
but if in doubt consult the electrode
manufacturers literature.
5.02.2 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 make it brittle. 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 preheating 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
(refer to table below). 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 and all will
work on even the most basic of welding machines.
Metals being joined Electrode Comments
Mild steel 6013 Ideal electrodes for all general
purpose work. Features include out
standing operator appeal, easy arc
starting and
low spatter.
Mild steel 7014 All positional electrodes for use on
mild and galvanized steel furniture,
plates, fences, gates, pipes 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 resistance. Ideal for
dairy work, etc. on stainless steels.
Copper, Bronze, Brass,
etc. Bronze
5.7 ERCUSI-A
Easy to use electrode for marine
fittings, water taps and valves, water
trough float arms, etc. Also for
joining copper to steel and for bronze
overlays on steel shafts.
High Alloy Steels,
Dissimilar Metals,
Crack Resistance.
All Hard-To-Weld Jobs. 312-16 It will weld most problematical jobs
such as springs, shafts, broken joins
mild steel to stainless and alloy steels.
Not suitable for Aluminium.