Abstract

To study intergranular corrosion (IGC) characteristics, two cast grades of duplex stainless steels, 5A and 5A stabilized with niobium, were produced in a vacuum induction melting furnace. The samples were tested under three different heat-treatment conditions that were selected using a property diagram generated through the TCFE8 database of the Thermo-Calc® software (Thermo-Calc Software, Solna, Sweden). A Feritscope FMP30® (Fischer Technology, Inc., Windsor, CT) was used to measure the ferrite phase content in the samples and compared with that specified in the property diagram. Metallurgical characteristics were analyzed through optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry. Each heat-treated sample possessed a distinct texture due to the formation of various intermetallic phases in the alloy. The corrosion behavior of the samples was studied using an oxalic acid etch test. Double-loop electrochemical potentiokinetic reactivation and sulfuric acid tests were conducted on the niobium-stabilized samples, and the results demonstrated that the samples possess superior resistance to corrosion compared to those not stabilized with niobium. The addition of niobium produced a mixture of niobium compounds that suppressed the chromium depletion and reduced the degree of sensitization. This study demonstrated the potential of using niobium as a stabilizer in the duplex stainless steel alloy to considerably reduce IGC.

References

1.
Javaherdashti
,
R.
,
Nwaoha
,
C.
, and
Tan
,
H.
,
Corrosion and Materials in the Oil and Gas Industries
,
CRC press
,
Boca Raton, FL
,
2013
, pp. 
291
292
.
2.
Liljas
,
M.
, “
80 Years with Duplex Steels: A Historic Review and Prospects for the Future
.” Presented at the
Sixth European Stainless Steel Conference
, Helsinki, Finland, June 10–13,
2008
,
Jernkontoret
,
Stockholm, Sweden
, pp. 
335
540
.
3.
Voronenko
,
B. I.
, “
Austenitic-Ferritic Stainless Steels: A State of the Art Review
,”
Met. Sci. Heat Treat.
, Vol. 
39
, No. 
10
,
1997
, pp. 
428
437
, https://doi.org/10.1007/BF02484228
4.
Kisasoz
,
A.
,
Gurel
,
S.
, and
Karaaslan
,
A.
, “
Effect of Annealing Time and Cooling Rate on Precipitation Processes in a Duplex Corrosion-Resistant Steel
”.
Met. Sci. Heat Treat.
, Vol. 
57
, Nos. 
9–10
,
2016
, pp. 
544
547
, https://doi.org/10.1007/s11041-016-9919-5
5.
Sedriks
,
A. J.
,
Corrosion of Stainless Steels
,
John Wiley & Sons, Inc.
New York, NY
,
1996
, 464p.
6.
Knyazeva
,
M.
and
Pohl
,
M.
, “
Duplex Steels. Part II: Carbides and Nitrides
,”
Metall. Microstruct. Anal.
, Vol. 
2
, No. 
5
,
2013
, pp. 
343
351
, https://doi.org/10.1007/s13632-013-0088-2
7.
Bond
,
A. P.
and
Lizlovs
,
E. A.
, “
Intergranular Corrosion of Ferritic Stainless Steels
,”
J. Electrochem. Soc.
, Vol. 
116
, No. 
9
,
1969
, pp. 
1305
1311
, https://doi.org/10.1149/1.2412306
8.
Gunn
,
R. N.
,
Duplex Stainless Steels: Microstructure, Properties and Applications
,
Wood Head Publishing Ltd
,
Cambridge, UK
,
1997
, 216p.
9.
Jones
,
D. A.
,
Principles and Prevention of Corrosion
,
Prentice Hall
,
Upper Saddle River, NJ
,
1995
, 572p.
10.
Cavazos
,
J. L.
, “
Characterization of Precipitates Formed in a Ferritic Stainless Steel Stabilized with Zr and Ti Additions
,”
Mater. Charact.
, Vol. 
56
, No. 
2
,
2006
, pp. 
96
101
, https://doi.org/10.1016/j.matchar.2005.05.006
11.
Park
,
J. H.
,
Seo
,
H. S.
, and
Kim
,
K. Y.
, “
Alloy Design to Prevent Intergranular Corrosion of Low-Cr Ferritic Stainless Steel with Weak Carbide Formers
,”
J. Electrochem. Soc.
, Vol. 
162
, No. 
8
,
2015
, pp. 
C412
C418
, https://doi.org/10.1149/2.1001508jes
12.
Itman Filho
,
A.
,
Silva
,
R. V.
,
Cardosoa
,
W. D. S.
, and
Casteletti
,
L. C.
, “
Effect of Niobium in the Phase Transformation and Corrosion Resistance of One Austenitic-Ferritic Stainless Steel
,”
Mater. Res.
, Vol. 
17
, No. 
4
,
2014
, pp. 
801
806
, https://doi.org/10.1590/1516-1439.190113
13.
Chandrasekar
,
A.
,
Anburaj
,
J.
,
Narayanan
,
R.
,
Balusamy
,
V.
, and
Mohamed Nazirudeen
,
S. S.
, “
Solubility of Nitrogen in Superaustenitic Stainless Steels during Air Induction Melting
,”
J. Mater. Eng. Perform.
, Vol. 
22
, No. 
4
,
2013
, pp. 
964
973
, https://doi.org/10.1007/s11665-012-0364-3
14.
ASTM A890/A890M – 13
Standard Specification for Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-Resistant, Duplex (Austenitic/Ferritic) for General Application
(superseded),
ASTM International
,
West Conshohocken, PA
,
2013
, www.astm.org
15.
Stradomski
,
Z.
and
Dyja
,
D.
, “
Characterization of Solidification and Solid State Transformation in Duplex Cast Steel: Thermo-Calc Investigation
,”
Arch. Foundry Eng.
, Vol. 
7
, No. 
3
,
2007
, pp. 
269
272
.
16.
Niagaj
,
J.
and
Mazur
,
Ł.
, “
Review of Methods for Measurement of Ferrite Content in High Alloyed Steels and Their Welded Joints
,”
Weld. Int.
, Vol. 
28
, No. 
5
,
2012
, pp. 
345
353
, https://doi.org/10.1080/09507116.2012.708490
17.
Zucato
,
I.
,
Moreira
,
M. C.
,
Machado
,
I. F.
, and
Lebrão
,
S. M. G.
, “
Microstructural Characterization and the Effect of Phase Transformations on Toughness of the UNS S31803 Duplex Stainless Steel Aged Treated at 850 °C
,”
Mater. Res.
, Vol. 
5
, No. 
3
,
2002
, pp. 
385
389
, https://doi.org/10.1590/S1516-14392002000300026
18.
ASTM A262 – 15
Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels
,
ASTM International
,
West Conshohocken, PA
,
2015
, www.astm.org
19.
ISO 3651-2:1998(en)
Determination of Resistance to Intergranular Corrosion of Stainless Steels — Part 2: Ferritic, Austenitic and Ferritic-Austenitic (Duplex) Stainless Steels — Corrosion Test in Media Containing Sulfuric Acid
,
International Organization for Standardization
,
Geneva, Switzerland
,
1998
, www.iso.org
20.
Aydoğdu
,
G. H.
and
Aydinol
,
M. K.
, “
Determination of Susceptibility to Intergranular Corrosion and Electrochemical Reactivation Behavior of AISI 316L Type Stainless Steel
,”
Corros. Sci.
, Vol. 
48
, No. 
11
,
2006
, pp. 
3565
3583
, https://doi.org/10.1016/j.corsci.2006.01.003
21.
Turnbull
,
A.
,
Francis
,
P. E.
,
Ryan
,
M. P.
,
Orkney
,
L. P.
,
Griffiths
,
A. J.
, and
Hawkins
,
B.
, “
A Novel Approach to Characterizing the Corrosion Resistance of Super Duplex Stainless Steel Welds
,”
Corrosion
, Vol. 
58
, No. 
12
,
2002
, pp. 
1039
1048
, https://doi.org/10.5006/1.3280793
22.
Stoulil
,
J.
and
Bystriansky
,
J.
, “
Modified EPR-DL Method for Detection of the Spinodal Decomposition of 2205 Duplex Stainless Steel
,”
Mater. Corros.
, Vol. 
63
, No. 
7
,
2012
, pp. 
593
597
.
23.
May
,
J. E.
,
de Sousa
,
C. A. C.
, and
Kuri
,
S. E.
, “
Aspects of the Anodic Behavior of Duplex Stainless Steels Aged for Long Periods at Low Temperatures
,”
Corros. Sci.
, Vol. 
45
, No. 
7
,
2003
, pp. 
1395
1403
, https://doi.org/10.1016/S0010-938X(02)00244-5
24.
Park
,
C.-J.
and
Kwon
,
H.-S.
, “
Effects of Aging at 475 °C on Corrosion Properties of Tungsten-Containing Duplex Stainless Steels
,”
Corros. Sci.
, Vol. 
44
, No. 
12
,
2002
, pp. 
2817
2830
, https://doi.org/10.1016/S0010-938X(02)00079-3
25.
Duret-Thual
,
C.
,
Bonis
,
M.
, and
Crolet
,
J.-L.
, “
Application of the EPR Method to Duplex Stainless Steels
,”
Mater. Corros.
, Vol. 
52
, No. 
1
,
2001
, pp. 
37
44
, https://doi.org/10.1002/1521-4176(200101)52:1<37::AID-MACO37>3.0.CO;2-F
26.
Majidi
,
A. P.
and
Streicher
,
M. A.
, “
The Double Loop Reactivation Method for Detecting Sensitization in AISI 304 Stainless Steels
,”
Corrosion
, Vol. 
40
, No. 
11
,
1984
, pp. 
584
593
, https://doi.org/10.5006/1.3581921
27.
Amadou
,
T.
,
Sidhom
,
H.
, and
Braham
,
C.
, “
Double Loop Electrochemical Potentiokinetic Reactivation Test Optimization in Checking of Duplex Stainless Steel Intergranular Corrosion Susceptibility
,”
Metall. Mater. Trans. A.
, Vol. 
35
, No. 
11
,
2004
, pp. 
3499
3513
, https://doi.org/10.1007/s11661-004-0187-4
28.
Matula
,
M.
,
Hyspecka
,
L.
,
Svoboda
,
M.
,
Vodarek
,
V.
,
Dagbert
,
C.
,
Galland
,
J.
,
Stonawska
,
Z.
, and
Tuma
,
L.
, “
Intergranular Corrosion of AISI 316L Steel
,”
Mater. Charact.
, Vol. 
46
, Nos. 
2–3
,
2001
, pp. 
203
210
, https://doi.org/10.1016/S1044-5803(01)00125-5
29.
de Melo
,
E. B.
,
Magnabosco
,
R.
, and
de Moura Neto
,
C.
, “
Influence of the Microstructure on the Degree of Sensitization of a Duplex Stainless Steel UNS S31803 Aged at 650°C
,”
Mater. Res.
, Vol. 
16
, No. 
6
,
2013
, pp. 
1336
1343
, https://doi.org/10.1590/S1516-14392013005000125
30.
Moura
,
V. S.
,
Lima
,
L. D.
,
Pardal
,
J. M.
,
Kina
,
A. Y.
,
Corte
,
R. R. A.
, and
Tavares
,
S. S. M.
, “
Influence of Microstructure on the Corrosion Resistance of the Duplex Stainless Steel UNS S31803
,”
Mater. Charact.
, Vol. 
59
, No. 
8
,
2008
, pp. 
1127
1132
, https://doi.org/10.1016/j.matchar.2007.09.002
31.
Číhal
,
V.
,
Lasek
,
S.
,
Blahetová
,
M.
,
Kalabisová
,
E.
, and
Krhutová
,
Z.
, “
Trends in the Electrochemical Polarization Potentiodynamic Reactivation Method – EPR
,”
Chem. Biochem. Eng. Q.
, Vol. 
21
, No. 
1
,
2007
, pp. 
47
54
.
32.
Pohl
,
M.
,
Storz
,
O.
, and
Glogowski
,
T.
, “
Effect of Intermetallic Precipitations on the Properties of Duplex Stainless Steel
,”
Mater. Charact.
, Vol. 
58
, No. 
1
,
2007
, pp. 
65
71
, https://doi.org/10.1016/j.matchar.2006.03.015
This content is only available via PDF.
You do not currently have access to this content.