Tweco 201 ts Thermal Arc - Manual (Page 35)

OPERATION THERMAL ARC 161 STL, 201 TS
Manual 0-5203 4-5 Operation
4.03 STICK (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.
4.04 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, 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 neces-
sary 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 gen-
eral 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.