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S34700 (347)
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Introduction:
The older and higher carbon 18Cr,8-10Ni type steels
are prone to sensitization and intergranular attack
in weld zones and slower cooling sections. This steel
avoids such attack by stabilization with niobium.
It could have equally been designated 304Nb. However,
the advent of
AOD/VOD refining allowing easier production of less-sensitizable
low-carbon (0.03% max) grades has lessened the need
for this stabilized steel.
The corrosion behaviour of this alloy in natural environments
is very similar to the UNS S30400
and S30403 alloys. Architecturally,
it may not be adequate for near-industrial or coastal
locations in Europe. Satisfactory in many low-chloride
waters, it is prone to pitting or crevice corrosion
in seawater. Water treatment, galvanic protection
and deaeration can influence its performance.
Metallurgy:
The precipitation of chromium carbides in
higher-carbon steels locally depletes the steel of
chromium, thereby sensitizing the alloy to corrosion
by intergranular attack. Niobium has a stronger affinity
for carbon than chromium and additions exceeding 10xC
ensures the formation of niobium carbides thus minimizing
chromium depletion.
Composition:
| Element |
Minimum
(%) |
Maximum
(%) |
| Chromium |
17.00 |
19.00 |
| Nickel |
9.00 |
13.00 |
| Manganese |
- |
2.00 |
| Carbon |
- |
0.08 |
| Niobium |
10
x C |
1.00 |
|
Similiar Specifications:
ISO 2604 50
ISO 683/13 16
17-19%Cr, 9-12%Ni, <2%Mn, <0.08%C, 10 x C-1.0%Nb
EURONORM X6 CrNiNb 18 10
17.0-19.0%Cr, 9.0-12.0%Ni, <2.0%Mn, <0.08%C,
(10 x %C)-1.0%Nb
ASTM UNS S34700 347
17-19%Cr, 9-13%Ni, <2.0%Mn, <0.08%C, 10 x C-1.0%Nb
BS 347S31
17-19%Cr, 9-12%Ni, <2%Mn, <0.08%C, 10 x C-1.0%Nb
DIN X6
CrNiNb 18 10 1.4550
17-19%Cr, 9-12%Ni, <2%Mn, <0.08%C, 10 x C-1.0%Nb
JIS SUS 347
17-19%Cr, 9-13%Ni, <2%Mn, <0.08%C, >10 x
C%Nb
Applications:
Because of competition from the low-carbon 30400 grades,
applications for this alloy are now more
confined
to heat resisting components for power stations, furnaces,
etc, and to heavier sectioned
welded plant for nearer
ambient temperature use. Other uses are similar to
the S30400 stainless
steels.
Product Forms:
Plate,sheet
& strip
ISO 2604 /4 P50
EURONORM X6
CrNiNb 18 10 88-86/2, 88-86/3
ASTM UNS S34700
347 167, 240, 480
BS 347S31 1449/2, 1501/3
DIN X6
CrNiNb 18 10 1.4550 17440,
17441
JIS SUS 347 4304, 4305, 4307
Bar & long products
EURONORM X6
CrNiNb 18 10 88-86/1
ASTM UNS S34700
347 276, 479, 484
BS 347S31 970/1, 1502
DIN X6
CrNiNb 18 10 1.4550 17440
JIS SUS 347 4303, 4308, 4318, 4311
Forgings & others
ISO 2604 /1 F50
EURONORM X6
CrNiNb 18 10 88-86/1
ASTM UNS S34700
347 314, 473, 484, 182, 403, 744
BS 347S31 970/1, 1503
DIN X6
CrNiNb 18 10 1.4550 17440
JIS SUS 347 4319, 3214
Tube and/or pipe
ISO 2604 /2 TS50, /5 TW50
BS 347S31 (3605)
DIN X6
CrNiNb 18 10 1.4550 17455,
17456, 17457, 17458
JIS SUS 347 3463, 3459
ASTM UNS S34700
347 213, 249, 269, 271, 450, 511, 554, 632, 778
Pipe
ASTM UNS S34700
347 312, 358, 376, 409, 430, 530, 813, 814
General
ISO 683/13 16
BS 347S31 5500
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Page Last Modified: 7/04/06 17:58
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