347 UNS S34700 Columbium and tantalum have been added to
347 to form columbium carbide in preference to chromium
carbide in the sensitization range. Columbium stabilization
is desired because its carbides are better retained
in welds. It also delays becoming sensitized during
exposures to temperatures in the sensitization range.
Type 347 does require more care due to the presence
of columbium.
This grade has similar applications to Type 321,
others include aircraft exhausts and manifolds,
fire walls, extended welding of heavy sections for
high temperature use, heavy wall welded equipment
and heat exchangers.
chemical composition limits
(%)
Carbon
C
Manganese
Mn
Phosphorus
P
Sulfur
S
Silicon
Si
Chromium
Cr
Nickel
Ni
Carbide+Tantalum
Cb+Ta
0.08
2.00
0.045
0.030
1.00
17.00-19.00
9.00-13.00
10xC min./1.10 max
Representative mechanical property
condition
tensile strength
yield strength
elongation
rockwell
KSi
MPa
ksi
mpa
in
2 inches %
Annealed
75
(515)
30
(205)
40
B-88
max.
*Minimum
Chemical composition is percent maximum unless
shown as a range or a minimum.
Information presented as a guide for reference
purposes only and is not intended for product
design or application.
