Transcript COMPOSITION OF STAINLESS STEELS TESTED

COMPOSITION OF STAINLESS STEELS TESTED
UNS
AISI
Trade
Name
316L
Chemical Analysis (% weight)
Mo
Cu
W
N
PRENW
(1)
Cr
Ni
17,2
12,6
2,6
0,05
25
5,5
3,2
0,17
34
6,3
6,9
17,8
21,8
30,3
22
24,7
3,6
3,8
6,0
7,3
3,4
4,7
6,3
0,25
0,28
0,20
0,48
0,07
0,40
0,19
41
41
43
56
38
54
43
31803
SAF2205
22
32520
32750
312 54
32654
08028
08932
08926
UR52N+
SAF2507
254SMO
654SMO
SAN 28
URB66
URB26
25
24,9
19,9
24,5
26,7
24,5
20
1,5
0,7
0,4
0,9
1,5
0,8
0,5
2
PRENW : Cr + 3.3 Mo +1.6 W + 16 N
Pitting Potential, mV/SCE
PITTING CORROSION RESISTANCE
NaCl 30 g/l - ASTM G61
N06 622
1000
URB66
800
S 31726
600
UR45N
400
N08926
904L
32 520
316L
200
304L
0
20
30
40
50
60
70
Temperature, °C
80
90
100
LONG TERM IMMERSION TESTING
in
NATURAL SEA WATER
(Crevice Corrosion)
REST POTENTIAL OF MCW SAMPLES in
MEDITERRANEAN SEA
Rest Potential, mV/Ag-AgCl
+400
32550, 08926, URB66 :No Crevice Cor
08904
31803
0
- 400
31603
30403
Crevice Corrosion
100
0
MCW : multi crevice washers
Time, Days
200
EFFECT OF CLIMATIC CONDITIONS
PRENW > 40 :UR52N+, URB26, URB66 (MCW samples):
no Crevice Corrosion
Rest Potential, mV/Ag-AgCl
+400
PREN > 40
no corrosion
316L
0
Crevice
-400
Mediterranean Sea, F
North Sea, N
Atlantic Sea, F
0
100
Time, days
200
CREVICE CORROSION in NATURAL SEA WATER
Win ter + Su mmer immersion tests , 3000 h ou rs each
G
C
B
K
T
Italy
France
France
Sweden
Norway
316L
5/5
5/5
0/4
0/4
4/4
31803
++
+
+
0/5
+
32520
+
+
0/5
0/5
+
32750
0/4
+
0/5
+
+
31254
+
+
0/5
0/5
0/5
32654
+
0/5
0/5
+
0/4
08028
+
+
+
0/5
+
08926
0/5
0/5
0/5
+
0/5
Steel
+/++
5/5
one/several depassivated area, no weight loss
crevice corrosion on 5 coupons out of 5
MATERIAL SELECTION FOR SEAWATER
No fitting nor Crevice geometry
Crevice Geometry
SERVICE
Water velocity
10
T(°C)
0
UR 45N - S31803
S 32 205
Free Cl2 (ppm)
Stagnant
0.5
Flange with Washer (1)
> 1 m/s
1
0
0.5
1
0
0.5
1
Threaded Joint (2)
0
316L UR B26/N08926
URB26/08926
or
UR B26/N08926
or
+/
+/
or
UR 45N UR 52N S32520 UR 52N S32 520
UR 52N+/S32 520
0.5
1
UR B66
S31266
20
TITANIUM
30
UR B66 - S31266
40
If some fretting or wear is involved, the material selection
has to be adapted (please, contact corrosion specialists)
(1)
(2)