259
266
93
9
Journal of Chinese Corrosion Engineering, Vol.18 No.3, PP. 259~266 (2004)
2205
H2SO4 / HCl
Selective Dissolution of 2205 Duplex Stainless Steel in H2SO4 / HCl
Solution
I-Hsuang Lo, Wen-Ta Tsai*
2205
H2SO4 / HC l
2205
-
H2SO4 / HC l
H2SO4
HC l
-
ABSTRACT
The difference in chemical composition between the two constituent phases in duplex
stainless steel (DSS) could result in the occurrence of selective dissolution. In this study, two
obvious peaks in the active-to-passive transition zone caused by selective dissolution in the mixed
H2SO4/HCl solution of 2205 DSS was found. Microstructure analysis and phase identification
were performed after potentiostatic test in these two separate potential using scanning electron
microscopy (SEM) and energy dispersive spectroscopy (EDS). The peak appeared at a lower
potential region was associated with the preferential dissolution of ferrite phase while that for
austenite at a higher potential. In the mixed H2SO4/HCl solution, the dissolution of ferrite was
favored by increasing the concentration of H2SO4, while enhanced dissolution of austenite was
found at a high concentration HCl.
Keyword : Duplex stainless steel; Active-to-passive transition; Selective dissolution
Department of Materials Science and Engineering
National Cheng Kung University
*
([email protected])
-259-
93
9
100ml H2O)
1.
95
3
Matrox Inspector
(Austenite,
(Ferrite,
)
)[1,2]
2.3
[3]
2.3.1
[4~6]
EG&G Model
273
(selective dissolution)
SiC
[7~10]
SO 4
2-
Cl
0.1
-
m Al2O3
H 2SO 4
-
#2000
HCl
(SCE)
1
mV/sec
-
2.3.2
-
EG&G Model
273
2205
H2SO4
HCl
H2SO4
H2SO4
HCl
HCl
25
1
2.4
2.
(SEM)
2.1
2205
(EDS)
1
(Mo)
2205
1100
(Fe)
(Cr)
(Ni)
(Mn)
/0.5h
H2SO4
HCl
H2SO4
HCl
0.25 ~ 2M
3.
2
25
3.1
1
1
2.2
2205
(
2205
2000
Murukami
0.1
SiC
(
m Al2O3
(20g KOH + 20g K3Fe(CN)6 +
0.47
-260-
0.53
)
)
2205
H 2 SO 4 / HCl
5 mV
3.2
2
2205
max
HCl
I
-
max
I
I
(0.25 ~0.5M)
max
HCl
max
I max
3
HCl
6
4
I
2M
max
SEM/EDS
HCl
HCl
3
E
max
HCl
E
Mn
Mo
I
HCl
(0.7 ~ 1M)
Cr
HCl
HCl
H2SO4
-380 ~ -200 mV
Ni
max
35mV
2M H 2SO 4 + 0.5M
3
E
4
max
HCl
3.3.2 H2SO4
2M H2SO4 + 0.5M HCl
0.5 M HCl
1M)
H2SO4
(0.25 ~
2205
7
H2SO4
7
E max E
max
I
4
E
max
E
max
H 2 SO 4
I
max
I
15mV
max
10mV
2
I
E
0.25M
E
max
ma
max
max
1M
H 2 SO 4
I
max
(0.25~ 0.5M)
H2SO4
I
max
~ 1M)
I
max
H2SO4
8
(0.7
H2SO4
3.3 H2SO4/HCl
H2SO4
HCl
0.5 M HCl
H 2SO 4/HCl
H2SO4
E max
E
I
H2SO4
max
I
max
3.3.1 HCl
5
max
2205
~ 1M) HCl
(0.25
2M H2SO4
HCl
4.
-
1. 2205
HCl
E
max
max
E
max
I
max
-
I
HCl
3
2M H2SO4
0.25M
1M
HCl
E
H2SO4/HCl
max
-261-
93
2.
2M
H2SO4
HCl
HCl
3.
H2SO4
0.5M
9
2003
7
22
2003
9
25
2003
10
22
HCl
H2SO4
(
NSC89-2216-E-006-
068)
1. C. D. S. Tuck, J. M. Skyes, and L. F. GrafiasMesias, Duplex Stainless Steels, Paper 15,
1.
Glasgow, The Welding Institute, Abington,
2205
Table 1 Chemical composition of 2205 DSS.
Cambridge 1994.
2. L. F. Grafias-Mesias, J. M. Skyes, and C. D. S.
Tuck, Corrosion Science, 38 (1996) 1319.
3. K. Ravindranath and S. N. Mailhotra, Corrosion
Science, 37 (1995) 121.
4. E. Symniotis, Corrosion, 46 (1990) 2.
5. E. Symniotis, Corrosion, 51 (1995) 8.
6. C. O. A. Olsson, Corrosion Science, 37 (1995) 467.
2.
7. M. Femenia, J. Pan, and C. Leygraf, Journal of The
(M)
Table 2 Compositions (M) of solutions used for test.
Electrochemical Society, 149 (2002) pp. B187B197.
8. X. F. Yang, and J. E. Castle, Surface and Interface
Analysis, 33 (2002) pp. 894-899.
9. A. J. Aldykiewicz, JR., and H. S. Isaacs, Corrosion
Science, 40 (1998) pp. 1627-1646.
10. M. Femenia, J. Pan, C. Leygraf, and P. Luukkonen,
Corrosion Science, 43 (2001) pp. 1939-1951.
-262-
2205
3.
2205
H 2 SO 4 / HCl
2M H2SO4 + xM HCl
E
max
max
E
max
I
max
I
HCl
Table 3 The magnitudes of E max, E max, I max
and I max of 2205 DSS in 2.0M H2SO4 + xM
HCl solution.
4.
2205
0.5M HCl + xM H2SO4
E
max
max
E
max
I
max
2.
I
H2SO4
2205
2M H2SO4 + 0.5M HCl
Figure 2 Potentiodynamic polarization curve of 2205
Table 4 The magnitudes of E max, E max, I max
DSS in 2M H2SO4 + 0.5M HCl solutions.
and I max of 2205 DSS in 0.5M HCl + xM
H2SO4 solution.
3.
50
1.
2205
m
2M H2SO4 + 0.5M HCl
E max
2205
Figure 3 Micrograph of 2205 DSS in 2M H2SO4 + 0.5M
Figure 1 Triple-axis micrograph of 2205 DSS.
HCl solution after applying E max potential
for 3 hours.
-263-
93
4.
2205
9
2M H2SO4 + 0.5M HCl
E
max
6.
Figure 4 Micrograph of 2205 DSS in 2M H2SO4 + 0.5
M HCl solution after applying E
2 M H2SO4
max
2205
HC l
potential for 3 hours.
Figure 6 Effect of HCl concentration on the magnitudes
of E
max, E
max, I
max and I
max of
2205 DSS in 2.0M H2SO4 + xM HCl solutions.
5.
2205
HCl
2
7.
M H2SO4
2205
H2SO4
0.5M HCl
Figure 5 Potentiodynamic polarization curves of 2205
Figure 7 Potentiodynamic polarization curves of 2205
DSS in 2M H2SO4 solutions with various HCl
DSS in 0.5M HCl solutions with various
concentration.
H2SO4 concentration.
-264-
2205
8.
0.5M HCl
H2SO 4 / H C l
2205
H2SO4
Figure 8 Effect of H 2 SO 4 concentration on the
mangitudes of E max, E max, I max and
I
max of 2205 DSS in 0.5M HCl + xM
H2SO4 solutions.
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93
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