URANUS S1
A 4% Si, austenitic stainless steel resistant to nitric acid solutions
Research carried out in about the last 20 years in
Industeel Research Center shows that a strong addition of
silicon to austenitic stainless steels of the 18/10 type has
a favourable influence on resistance to transpassive intergranular corrosion.
This type of corrosion develops particularly in very
concentrated nitric environments (> 90 %) up to boiling
point, also in strongly oxydising nitric environments
(oxidising ions present such as : hexavalent chromium,
pentalivalent vanadium - ferritic salts etc...)
Our UR S1 steel grade puts in a concrete form the results
of our research in this domain.
Standards
EURONORM
1.4361 X1 Cr Ni Si 18-15-4
ASTM
UNS S30600
Chemical analysis
Typical values (weight %)
C
Cr
Ni
Mo
N
Others
Si =4
< .015
17
14.5
PREN [Cr%] + 3.3 [Mo%] +16 [N%] > 17
Mechanical properties
Tensile properties
C
20
100
200
300
400
68
212
392
572
752
Y.S. 0.2%
ksi
MPa
35
240
27
185
21
140
18
125
17
115
Minimum guaranteed values
UR S1 Rev 3 - 11.02.2011 - page 1
Y.S. 1%
ksi
MPa
38
260
31
210
25
175
22
155
22
150
UTS
MPa
540
490
450
420
150
ksi
78
71
65
61
58
El%
45
45
45
40
40
Physical properties
Density : 7700 kg/m3
Interval
Thermal
temperature expansion
Resistivity
C
20-100
a x10-6K-1
16.5
20
68
W cm
75
20-300
20-500
18
19
200
400
392
752
Shear
Thermal Specific Young
modulus modulus
conductivity heat
E
G
W.m-1.K-1 J.kg-1.K-1
GPa
GPa
15.1
500
200
77
-
Fabrication
Hot Forming
Forming temperature 1150/900C (2100/1650F)
(removal of grease in oxidising environment necessary) in
order to avoid all risks of recarburation.
Cold forming
Easy with all current methods : bending, profiling,
stamping.
Heat treatment
Solution annealing at 1100/1150C (2010/2100F) cooling in water (holding time 1 to 2 min. per mm of
plate thickness oxidising environment).
Welding
Welding UR S1 requires well qualified welders. It is carried
out both TIG and MIG processes (recommended
technique) with our welding filler metal SOUDINOX S1)
and under inert gas protection.
Arc extingnishess are indispensable to avoid craters. It is
also necessary to adapt speed and compatible amperage
in order to limit the temperature between passes.
Heat treatment after welding is not necessary. For very
severe conditions of use, it could be advisable.
However, pickling after welding is necessary and then
continue immediately with a passivation treatment.
For any further information, please contact our technical
assistance specialists.
Cutting
All classical mechanical or thermal processes for stainless
steels.
UR S1 Rev 3 - 11.02.2011 - page 2
520
540
186
172
71
65
Corrosion performances
Pickling
Attack rate
(mg/dm/24h)
TABLE 1
Thickness
Complete absence reduction
(mm/year)
on intergranular
penetration
2.0
500
This can be carried out using the following process :
nitrohydrofluoric bath HNO3 15 % (volume) HF (3 %)
volume water immersion for a few hours at 20C - 30
mins at 60 C careful rinsing in water.
Decontamination - Passivation
Nitric bath HNO3 25 % in volume for 30 mins at 20 C
(or 10 min. at 50C) washing in water.
400
1.5
300
1.0
200
0.50
100
0.25
Resistance to corrosion
UR S1 has a chemical composition adapted to work in the
transpassive zone. It resists perfectly to intergranular
corrosion.
Acid nitric
General corrosion rate
98% at room temperature Pratically non existent
98% boiling
0.20mm/year (Table 1)
28% boiling + 1g/l of
hexavalent chrome
0.30mm/year (Table 2)
28% boiling + 1g/l of trivalent chrome
0.30mm/year (Table 3)
with no trace of intergranular corrosion
1
2
3
4
HNO3 98% at boiling point
Attack rate
(mg/dm/24h)
TABLE 2
Thickness
reduction
(mm/year)
Complete absence
on intergranular
penetration
500
2.0
400
1.5
300
1.0
200
0.50
100
The graphs beside (Tables 1 to 3) show the influence of
silicon content for a Cr 16 % Ni , the content increasing
from 0.1 to 4.2 %.
Table 4 schematizes UR S1 behaviour in passive and transpassive conditions compared to some other grades.
Si(%)
2
3
4
HNO3 5N (Vi) 1 g/l
Si(%)
TABLE 3
Thickness
reduction
(mm/year)
Attack rate
(mg/dm/24h)
1.0
200
0.50
100
0.35
0.25
0.15
0.05
70
50
30
10
Si(%)
HNO3 N5 + Cr (III) 1 g/l
TABLE 4
Transpassivity
Corrosion
rate
25 Cr Ni 20
Passivity
Transition
Intergranular corrosion
Increasing
Cr 18 Ni 10
Cr 17 Ni 12 Mo 2.5
No intergranular corrosion
Cr 17 Ni 14 Si 4
UR S1
Electrochemical potential
Influence of Cr, Mo and Si on behaviour of stainless steels
in Passive and Transpassive conditions
UR S1 Rev 3 - 11.02.2011 - page 3
Applications
Mineral chemistry
Production of concentrated HNO3
Organic chemistry
Use of concentrated HNO3 (nitration)
Nuclear industry
Evaporator working in nitric environment, to concentrate
products of fusion
Metallurgical industry
Tanks - equipment destined for nitrogen sulphite mixtures
Chemical industry
Chrome sulphite mixtures, very oxyding solutions
Explosive industry
Aerospatial industry
Galvanotechnology
rocket tanks
Size range
Thickness
Width
Length
Hot rolled plates
Clad plates
5 up to 150 mm
3/16 to 6
6 up to 150 mm
1/4 to 6
Up to 3300 mm
Up to 130
Up to 14000 mm
Up to 46 ft
Up to 3300 mm
Up to 130
Up to 12000 mm
Up to 39ft
Other sizes are available on request, including 4100mm
(161,4") width plates
For any information,
please contact :
Industeel France
Le Creusot Plant
56 rue Clemenceau
F-71201 Le Creusot Cedex
Tel +33 (0)3 85 80 55 31
Fax +33 (0)3 85 80 54 11
Industeel Belgium
266 rue de Chatelet
B-6030 Marchienne au Pont
Tel +32 71 44 16 99
Fax +32 71 44 19 56
www.industeel.info
www.arcelormittal.com
This technical data and information represents our best knowledge at the time of printing. However, it
may be subject to some slight variations due to our ongoing research programme on corrosion resistant
grades.
We therefore suggest that information be verified at time of enquiry or order.
Furthemore, in service, real conditions are specific for each application. The data presented here is only
for the purpose of description and may only be considered as guarantees when our company has given
written formal approval.
UR S1 Rev 3 - 11.02.2011 - page 4
