1 ARCALOY®
Stainless Steel Covered
Electrode Coatings Coating
Types...Factors such as coating type and core wire analysis
can affect the corrosion resistance and
mechanical properties of the weld metals as well as the equipment that must be
used, position of welding,
radiographic standards, bead shape required and the total economics of making
the joint. Each of the
three coating types has its own area of application. Lime...coatings,
also known as lime fluorspar or basic, are generally associated with the suffix
-15 designation.
They give the cleanest weld metal, which is usually the lowest oxygen and inclusions
and are more resistant
to moisture and porosity. The weld metal tends to be tougher, more ductile, more
crack resistant
and have higher corrosion resistance. They also have good all-position characteristics
and are often
chosen for site work. They are normally usable only with direct current and should
be the choice of the
most demanding applications. AC-DC...coatings
can be used with alternating or direct current and have the suffix -16. The major
component is rutile, also known an
titania, with some limestone which is why the coating type is sometimes
referred to as basic-rutile. These
AC-DC electrodes are the most popular type, and have the following
characteristics: excellent starting
properties are obtained with all types of AC welding equipment. The arc
is stable, smooth, with fine spray
weld metal transfer and the bead is uniform, flat or slightly concave with
straight-line feathered edges. Penetration
is complete and the weld metal is free from porosity. Slag is
easily and completely removed without
secondary film which means less cleaning, grinding and polishing
time. Arcaloy AC-DC electrodes give
good out-of-position characteristics. The mechanical properties of
AC-DC weld metals are similar to weld
metal from lime coated electrodes except it can be stronger with
good ductility.
Plus...coatings are
also titania based, but in addition, contain a high proportion of silicates and
other acid components.
These electrodes are very easy to use on AC as well as DC and have the suffix
-17. Arcaloy Plus
coated electrodes were developed for application where the weld bead must be smooth
and blend into the
base metal to minimize grinding where a crevice can cause corrosion. The weld
bead is concave and has
minimal ripple. These Arcaloy Plus electrodes give a smooth spray transfer and
produce very low levels
of spatter. The acid slag tends to give the lowest carbon levels and higher silicon
levels. This can be ideal
for corrosion resistance, but for critical mechanical applications, the use of
a lime or even an AC-DC coating
is to be preferred.
