©
COPYRIGHT 2000 THE ESAB GROUP, INC. WELDING
FILLER METALS FOR STAINLESS
STEELS 5.1
INTRODUCTION TO STAINLESS STEEL
Stainless steel, introduced commercially
during the early 1930's, presented industry with a new "wonder
metal" with its shiny surface
and ability to resist rust and corrosion. This new steel
alloy also presented welding problems
that had not been previously encountered. It took many
years of research and experimentation
to develop successful welding filler metals and welding procedures
for this "rustless iron" as
it was then called. 5.1.0.1
Most of us think of stainless as an
attractive metal used for trim on our stoves and automobiles,
or as bright, easy-to-clean cooking utensils and cutlery. Besides being
used for its corrosion
resisting properties, however, stainless steel is used for low temperature applica-
tions, and for applications where its
resistance to scaling at high temperatures is important.
5.1.0.2 Stainless
steel is basically an alloy of iron and chromium. As the amount of chro-
mium added to a steel alloy is increased,
the corrosion resistance increases until the amount of
chromium reaches 11% to 12%, at which point it is considered a stainless steel.
The graph in
Figure 1 shows how the amount of chromium affects the rate of corrosion in a semi-rural,
outdoor air environment. Corrosion
rate will vary with the corrosive media to which the stain-
less steel is exposed and with the
type of stainless employed. LESSON
V MILD STEEL
STAINLESS STEEL
PERCENT CHROMIUM
2 4
6
8 10
12
14 .001
.0008 .0006
.0004 .0002
CORROSION RATE VERSUS PERCENT CHROMIUM
OUTDOOR ATMOSPHERE, SEMI-RURAL ENVIRONMENT
FIGURE 1
