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| Mailing Address |
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UKF Stainless Ltd
12 Buntsford Park Road
Bromsgrove
Worcestershire
B60 3DX
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| Telephone / Fax |
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| Tel: |
01527 578686 |
| Fax: |
01527 837792 |
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| Email |
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 info@ukfstainless.co.uk |
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S32750 / S39275
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Introduction:
A 'super' duplex steel with PREN about 42. Duplex
steels combine high strength with corrosion resistance.
Their resistance to stress-corrosion cracking in neutral
chlorides is superior to that of the 18/10 and 18/12/3
austenitics. In high chloride acidic or moderately
sour environments where hydrogen or sulphide stress
cracking is more likely, higher alloyed austenitics
need also to be considered.
Exposure to moderate and high temperatures and less
rapid cooling can cause embrittlement.
Impact values are high at room temperature with transition
temperatures of base material below -50°C. However,
the proportion and orientation of ferrite in welds
and base material may affect toughness at subzero
temperatures.
Metallurgy:
When ferrite forming elements (Cr,Mo,Si,Nb) are kept
at high levels but austenite promoting elements (Ni,Mn,N,C)
are reduced, stainless steels with a mixed or duplex
microstructure are produced. Mixtures of 40-60% of
either phase are near optimum.
Careful control of both the compositions and cooling
rate from high temperatures is necessary to prevent
the steel or weldment containing large amounts of
ferrite and/or traces of sigma phase that both embrittle
and impair corrosion resistance. Welding requires
control of heat-input and thermal cycles plus use
of special
consumables enriched with nitrogen and/or nickel.
Duplex stainless steels may suffer severe embrittlement
due to sigma phase formation in the 550-900°C
range and from alpha prime in the 280-550°C range.
The period for embrittlement may be short or long
depending on composition, time, temperature and cold
work.
Composition:
| Element |
Minimum
(%) |
Maximum
(%) |
| Chromium |
24.00 |
26.00 |
| Nickel |
6.00 |
8.00 |
| Molybdenum |
3.00 |
5.00 |
| Nitrogen |
0.24 |
0.32 |
| Manganese |
- |
1.20 |
| Carbon |
- |
0.03 |
| Copper |
- |
0.50 |
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Similiar Specifications:
EURONORM X2
CrNiMoN 25 7 4 (1.4410)
24-26%Cr, 6-8%Ni, 3.0-4.5%Mo, 0.20-0.35%N, <2%Mn,
<0.03%C
ASTM UNS S32750
24-26%Cr, 6-8%Ni, 3-5%Mo, 0.24-0.32%N, <1.2%Mn,
<0.03%C, <0.5%Cu
Applications:
Seawater handling and process systems in oil and gas
production.
Seawater cooling - heat exchangers.
Desalination plants - salt evaporation tubing.
Propeller and pump shafts.
Product Forms:
Plate,sheet & strip
ASTM UNS S32750
240
Bar
& long products
ASTM
UNS S32750 479
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Page Last Modified: 7/04/06 17:57
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