Tweco 161 S UK - Manual (Page 27)

OPERATION THERMAL ARC 161 S
Manual 0-5183 4-3 4-3 Operation
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
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, gener-
ally 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 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.