Manuscript number: P2065

Corrosion, Toughness, Weldability and Metallurgical Evaluation of

Cast Duplex Stainless Steels
by Carl D. Lundin, Songqing Wen, William J. Ruprecht (The University of Tennessee),
Raymond Monroe, Malcolm Blair (The Steel Founders Society of America)

Abstract
Five types of cast duplex stainless steels (A890 1B [and a modification thereof], 4A,
5A, 6A) were characterized as to their corrosion, toughness and weldability performance
and assessed microstructurally. These materials span the current range of alloys in
commercial use. The solution treated cast materials were compared to their wrought
equivalents in accord with ASTM A923. The cast duplex stainless steel materials were
found to exhibit performance characteristics equivalent and, in some cases, superior to
their wrought counterparts. The full range of testing strongly indicates that the cast
materials can be evaluated in accordance with the A923 specification, which currently
covers only limited wrought products.
The effect of welding on pitting performance was defined for both the cast and
wrought materials. This evaluation revealed that a very strong potential for degradation
of pitting resistance exists, upon autogenous welding, for both the wrought and cast
materials. This potential should be addressed when selecting the type of duplex stainless
steel for a particular service.

Key Words: cast duplex stainless steel, corrosion, toughness, weldability, microstructure
1

1. Introduction
Duplex stainless steels (DSS) are being specified for chloride containing
environments due to their enhanced pitting and stress corrosion cracking resistance.
They exhibit improved corrosion performance over the traditional austenitic stainless
steels. Duplex stainless steels can also offer improved strength properties and are
available in various wrought and cast forms.
In recent years, duplex stainless steels, in cast and wrought forms, have enjoyed
rapidly increasing popularity. However, the availability of these alloys in the cast form
has lagged behind the availability of the wrought form. Duplex stainless steel castings
are often used in as pumps and valves in a variety of applications and are important
components in all piping systems and, where unexpected service failures can result in
significant operational problems and expense, performance is critical. Thus, of concern
is variability and insufficient performance characteristics of DSS in all forms, which may
be related to in-service operational conditions. Therefore, it is necessary to have
available, suitable methods and procedures for enhancing the performance of DSS cast
materials and to introduce methods for defining performance characteristics prior to
service.
This paper presents part of the results of an Improved Process Procedures for
Upgrading & Repair of High Alloy Stainless Castings program sponsored by the
Department of Defense and the American Metal Casting Consortium, which involved two
major areas of endeavor, interrelated and leading to a more fundamental understanding of
the corrosion and fabrication behavior of DSS castings in comparison with wrought
materials.

2. Materials
Five types of cast DSS, together with their wrought counterparts, were characterized;
ASTM A890-4A, 5A, 6A, 1B, CD7MCuN and the wrought alloys, Alloy 2205, Alloy
2507, Zeron 100 and Ferralium 255. A total of sixteen cast heats and four wrought heats
were evaluated. The castings were characterized in the as-cast, solution annealed (SA)
static cast and SA centrifugal cast condition. The wrought materials were tested in the
form of SA plate. Weld evaluations, including extensive assessment of autogenous welds
and composite welds (SMAW), were performed on these materials.

3. Experimental Procedures and Results

3.1 ASTM A923 Methods A, B & C
ASTM A923, Standard Test Method for Detecting Detrimental Intermetallic
Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels, is a specification
that was developed for use with specific wrought duplex stainless steel (S31803).
The purpose of these test methods is to allow detection of the presence of
detrimental intermetallic phases in mill products to the extent that toughness or
corrosion resistance is significantly affected. It contains three test methods (A, B
& C). Method A is Sodium Hydroxide Etch Test for Classification of Etch
Structures of Duplex Stainless Steels, Method B is Charpy Impact Test for
Classification of Structures of Duplex Stainless Steels and Method C is Ferric
Chloride Corrosion Test for Classification of Structures of Duplex Stainless
Steels.

ASTM A923 was employed to test both the wrought and cast DSS in this
program. It should be noted that only S31803 (Alloy 2205) is covered in the
ASTM A923. However, base upon the evaluations conducted in the research
reported here in, it was determined that ASTM A923 can be a suitable
specification for both cast and wrought DSS of a variety of compositions, for
defining performance characteristics prior to service.
3.1.1 ASTM A923 Method A
ASTM A923 Method A, was used to screen specimens intended for
testing in Method B and Method C. The materials to be evaluated, were
mounted, polished and etched utilizing sodium hydroxide. The etched
surface was examined microscopically at 400X to 500X. Intermetallic
phases were revealed and, depending on the etching time (5 to 60s),
colored yellow or brownish. According to ASTM A923-A, signs of
precipitation or waviness along the interphase (austenite-ferrite)
boundaries are considered unacceptable. ASTM A923 Method A
classifies the etched structures into four categories:
Unaffected Structure - The ferrite has been etched without revelation of
an intermetallic phase. The interphase boundaries are smooth.
Possibly Affected Structure - The ferrite has been etched with isolated
indications of a possible intermetallic phase. The interphase boundaries
may show a fine scale waviness.

 Affected Structure - Indications of an intermetallic phase are readily

revealed before or simultaneously with the staining of the ferrite during
etching.
Centerline Structure - An intermetallic phase is observed as a
continuous or semi-continuous phase in the mid-thickness region of the
product, with or without the affected structure out side of the
mid-thickness region; indicative of segregation.
Samples, from ASTM A890-4A, 5A, 6A and 1B in the as-cast, and SA
condition together with their wrought counterparts, were polished and
NaOH etched according to ASTM A923 Method A. The typical
microstructures of NaOH etched ASTM A890-4A, 5A, 6A and 1B are
presented in Figures 1-1 to 1-4, respectively. All as-cast materials show
an Affected Structure, while all of the SA castings show Unaffected
Structures. Alloy 2205 and Alloy 2507 showed Possibly Affected
Structure. Zeron 100 and Ferralium 255 showed Unaffected
Structures.
3.1.2

ASTM A923 Method B

Test Method B determines in toughness characteristics which may
result from processing irregularities. Variations in toughness may be
attributable to an intermetallic phase or to other causes not necessarily
detectable by Test Method A. This test method follows the procedure for
conducting Charpy V-notch impact tests in accordance with ASTM A370
and E23 as a method of detecting the precipitation of detrimental

intermetallic phases in DSS. Unless otherwise specified, the Charpy

Impact test is performed at -40F (-40C). The acceptance criterion for
wrought base metal is 40 ft-lbs. (54.2J) at -40F (-40C).
A total of ten heats were tested per ASTM A923 Method B and the
results are presented in Table 1. The SA cast materials of ASTM A8904A, 5A 1B and CD7MCuN reveal better impact toughness than their
wrought counterparts at a test temperature of -40F (-40C). However, the
wrought super duplex stainless steel, Zeron 100, shows the highest
toughness at this temperature. Wrought Ferralium 255 is the only material
that did not pass ASTM A923 Method B criteria.
3.1.3

ASTM A923 Method C

Test Method C, is a 24 hour pitting corrosion test in 6% ferric
chloride, unless specified. The method detects a loss of corrosion
resistance associated with a local depletion of chromium and/or
molybdenum as a result of the precipitation of chromium-rich and possibly
molybdenum-rich phases, but not limited to intermetallic phases. An
affected structure should be associated with significant weight loss in the
corrosion test. It defines the test temperature for base metal samples as
25C, and for welds; 22C. The corrosion rate is calculated in accordance
with the weight loss and total surface area, using the formula below:
Corrosion rate (mdd*) = weight loss (mg) / [specimen area (dm2) x time
(days)]
* mdd: mg/ dm2/day

The acceptance criterion is that the corrosion rate shall not exceed 10mdd.
It was found that all SA castings met the weight loss criteria. The
SA + autogenously welded samples from ASTM A890-1B, 4A and
CD7MCuN did not meet the criteria. The test results according to
ASTM A923 Method C are summarized in Tables 2-1 through 2-5.

3.2 Critical Pitting Temperature (CPT) Testing

CPT evaluations were conducted in accordance with ASTM G48 Method C,
entitled Critical Pitting Temperature Test. CPT corrosion test samples of
1 X 1 X 1/8 in size with a 600-grit uniform surface finish were utilized. A
water bath, with an accuracy of 0.1C, was employed to control the test
temperature and 5C increments were used when defining the CPT. Each sample
was weighed to the nearest 0.0001g and immersed in a 6% FeCl3 solution when
the water bath came to equilibrium at the temperature of interest. The test period
is 24 hours. At the end of the test period, each sample was removed from
solution and cleaned and weighed. Weight loss was calculated.
We defined the evaluation criterion for pitting as: when a sample exhibits 2
or more pits when examined at a magnification of 20X is considered pitted.
The critical pitting temperature is defined as the lowest temperature at which
such pitting occurs. The CPT test was conducted using 5C increments,
therefore the accuracy of the test is 5C.
All materials, ASTM A890-4A, 5A, 6A, 1B and CD7MCuN, in the as-cast,
SA static and SA centrifugal cast condition, as well as the wrought counterparts,

were CPT tested. The castings of super duplex type ASTM A890-5A and 6A
exhibit the highest solution annealed CPT, as compared to ASTM A890-4A, 1B
and CD7MCuN, indicating improved pitting resistance. Autogenous welds
made on SA castings degraded the CPT of all materials. The extent of decrease
in CPT varied from alloy to alloy, and from heat to heat for the same alloy type.
The CPT test results of all alloy types can be summarized as follows:

The as-cast condition showed the worst pitting corrosion resistance. After
solution annealing, the pitting resistance significantly improved. There is a
slight variation in CPT between SA cast heats and casting procedures (SA
static casting and SA centrifugal castings).

Wrought materials have similar pitting corrosion resistance as compared to

castings in the SA condition.

Autogenous welding decreases the pitting corrosion resistance regardless of

the cast material condition, and also similarly adversely affects the wrought
materials.

The CPT test results are presented in Table 3-1 to 3-5.

Figures 2 through 4 show the microstructure of ASTM A890-4A Heats 1, in
the as-cast and SA condition, together with wrought counterpart Alloy 2205,
before and after the pitting test.
The microstructure of ASTM A890-4A Heat 1, in the as-cast condition, is
shown in Figure 2a. In the as-cast condition, austenite islands in a ferrite matrix
are evident, together with fine precipitates mainly along the ferrite/austenite
boundaries. Figure 2b shows an OLM micrograph of the pitting behavior of the

as-cast Heat 1. It is evident that pits initiate at the precipitates along the
ferrite/austenite boundaries and preferentially grow into ferrite.
The microstructure of ASTM A890-4A Heat 1 in the SA condition is shown
in Figure 3a. It is evident that the particles along the ferrite/austenite boundaries,
observed in the as-cast condition, are dissolved upon solution annealing.
Austenite islands with smooth boundaries (no precipitates) are obvious in the
ferrite matrix. Inclusions in the matrix remain unchanged after solution
annealing. Figure 3b shows an OLM micrograph of the pitting behavior of
ASTM A890-4A SA Heat 1. In the SA condition, pits will initiate above the
CPT at the ferrite/austenite boundaries and preferentially grow into austenite.
The microstructure of wrought counterpart Alloy 2205 is presented in
Figure 4a. A rolling texture, from hot working, followed by a solution annealing
and quenching, is evident in comparison with the cast material. The pitting
behavior of wrought Alloy 2205, in terms of the initiation and growth, was
determined to be identical to the corresponding ASTM A890-4A cast materials
in the SA condition (Figure 4b).
The optical features of the pitting behavior of autogenous welds on ASTM
A890-4A SA Heat 1 are shown in Figure 5. Pits were observed both in the
fusion zone and at the fusion line, as shown in the figure. A finer austenite
structure in the ferrite matrix is evident in the fusion zone, as compared to the
cast base metal. This finer austenite microstructure shows the original
solidification pattern in the autogenous weld fusion zone and reflects the rapid
cooling upon welding. The autogenously (no filler metal was added) welded

samples were tested in the as-welded condition. Thus, the fusion zone in these
autogenous welds is truly an Unmixed Zone. It is to be expected that
segregation of alloy elements in the fusion zone occurs during solidification.
Greater extent of element segregation tends to occur in the fusion zone adjacent
to the fusion boundary, as compared to the other fusion zone locations. The
segregation of Cr and Mo in the solidification structure can have a significant
influence on the corrosion behavior of autogenous welds. In addition, the loss of
nitrogen from the fusion zone during welding should be considered in regard to a
reduction of corrosion resistance of the autogenously welded fusion zone. The
degradation of corrosion resistance, in term of pitting resistance, is reflected by
the decrease in CPT. In this case, the CPT of SA ASTM A890-4A is 40C and
SA + autogenously welded; 30C. However, a significantly greater degradation
in CPT was obtained for some of the other alloys. Further research will be
conducted on welded duplex castings to determine the causes for these
differences.

3.3 Preliminary Study of Pitting Corrosion Performance of SMA Welded

Castings
Since autogenous welding is not generally the most utilized welding practice
for upgrading of castings or fabrication of DSS components, it is extremely
important to have a better understanding of the corrosion performance of
composite welds (weldments fabricated with matching or enhanced filler
materials). It should be recognized that welding processes using a filler metal

10

leaves a composite zone, an unmixed zone, a heat-affected zone (HAZ) and unaffected metal in the fabrication. The metallurgical characteristics of each zone
can be significantly different from that of the unaffected base material in terms
of microstructure, phase balance and alloy element distribution. Thus, the
corrosion performance of welded components can be expected to be different
from their respective original material condition. In addition, a paucity of data
exists upon which specifiers /engineers can base service performance of welds.
Thus, there is a need for a more comprehensive study of the behavior of welded
DSS components. In order to pave-the-way and to capture a glimpse of future
research work, trials involving pitting corrosion testing were initiated. Pitting
tests were conducted on DSS casting SMA welds for the determination of the
relative corrosion resistance between the composite zone, the unmixed zone, the
heat-affected zone (HAZ) and the SA cast base metal. A total of five heats, one
from each alloy system (ASTM A890-4A, 5A, 6A, 1B and CD7MCuN), were
selected for this study. A widely applicable conclusion, based on the results, can
be drawn as follows:

SMA welding has a significant effect on the corrosion performance of DSS

castings. Pits preferentially initiate in the composite zone, unmixed zone or
the heat-affected zone, depending on material.
The preliminary results of these trial pitting corrosion tests on DSS castings

clearly define the necessity for an additional detailed study on the corrosion
performance of the DSS composite welds.

11

3.4 Charpy Impact Testing

Charpy impact tests in according with ASTM A923 Method B, were
conducted in the temperature range of 80C to +20C on ASTM A890-4A, 5A,
6A, 1B, CD7MCuN and the wrought counterparts. Charpy toughness
transition curves for all tested materials are shown in Figure 6.
It should be noted that, the two SA heats of ASTM A890-4A revealed
significant differences in their toughness, as indicated in Figure 6. Figure 7
shows the microstructure of ASTM A890-4A Heat 2 in the SA condition. It is
clear that Heat 2 reveals a microstructure identical to Heat 1 (Figure 3a) in the
SA condition, in terms of austenite islands in a ferrite matrix. However, larger
inclusions were observed in the Heat 2 matrix as compared to Heat 1. It is
considered that these randomly distributed larger inclusions may have influenced
the Charpy toughness.

4. Conclusions
A significant database for the corrosion performance of the duplex stainless steel
castings has been established for cast DSS. Comparisons between DSS were made, and
heat-to-heat and alloy system-to-system, conclusions derived from the obtained results.
Conclusions can be drawn as follows:

Both the pitting and intergranular corrosion resistance of cast duplex stainless steel
are equal to or better than their wrought counterparts. Thus, cast and wrought
products can be evaluated to the same performance standards.

12

The corrosion test methods for wrought stainless materials are suitable for evaluation
of duplex stainless steel castings.

The data obtained in this study suggests that ASTM A923 can be expanded in
coverage to include the cast duplex materials of ASTM A890. Thus, one
specification will cover both wrought and cast materials making selection
independent of product form.

An appropriate screening test characterizing service performance of duplex stainless

steel castings is ASTM A923 Method A (NaOH Etch Test), which is currently
utilized for wrought S31803 (Alloy 2205) material. Cast duplex alloys can be added
to this specification upon the inclusion of appropriate photomicrographs.

Welding reduced the pitting and intergranular corrosion resistance for both the
wrought and cast duplex alloys of similar composition. The effect of welding should
be considered when selecting an alloy type for specific corrosion service. Thus, the
same fabrication considerations apply to the entire cast/wrought system.

Charpy impact test results show that castings can have equivalent toughness to their
wrought counterparts in the temperature range of 80C to +20C. Thus,
specification requirements are simplified for an entire system fabrication (both
wrought and cast).

5. Acknowledgements
The authors thank Steel Founders Society of America High Alloy Research
Committee, Advanced Technology Institute (ATI) , American Metal Casting Consortium

13

(AMC) and Department of Defense (DOD) for the support of the Evaluation of Duplex
Stainless Steel Castings program.

14

Table 1. ASTM A923 Method B Results

Code
Impact Energy
At -40F*
(ft-lbs)
ASTM A890-4A
55
Heat 1
ASTM A89-4A
150
Heat 2
Alloy 2205
50

Method B
P/F**
P
P
P

ASTM A 890-5A

80

Alloy 2507

44

ASTM A 890-6A

81

Zeron 100

172

ASTM A890-1B

82

CD7MCuN

62

CD7MCuN-CC

56

Ferralium. 255

23

* Charpy Impact test conducted according to ASTM A370 and E23 utilizing
V-notched Charpy test samples
** Acceptance criterion of ASTM A923 method B of base metal is 40 ft-lbs (54J) at 40F (-40C)

15

Table 2-1 Duplex Stainless Steel ASTM A923 Method C Ferric Chloride Corrosion Test Results,
ASTM A890-4A (6% FeCl3, Base Metal@25C & Weld Metal@22C,24 hrs.)
Material
Code
Condition
Corrosion Rate
P/F***
(mdd**)
ASTM A 890-4A
Heat 1
Solution annealed
0.73
P
ASTM A 890-4A

Heat 1

ASTM A 890-4A

Heat 2

ASTM A 890-4A

Heat 2

ASTM A 890-4A

Heat 3

ASTM A 890-4A

Heat 3

ASTM A 890-4A

CPT
(C)
40

SA
Autogenous welded
Solution annealed

65.93

30

2.19

35

SA
Autogenous welded
Solution annealed

65.93

0.00

50

415.20

Heat 4

SA
Autogenous welded
Solution annealed

0.00

45

ASTM A 890-4A

Heat 4

Solution annealed

15.10

20

ASTM A 890-4A

Solution annealed

2.12

50

SA
Autogenous welded
Wrought

33.34

15

Alloy 2205

Heat 4
CC*
Heat 4
CC*
Alloy 2205

0.00

40

Alloy 2205

Alloy 2205

Wrought
Autogenous welded

7.92

25

ASTM A 890-4A

* CC - centrifugal cast
2
** mdd - mg/dm /day
*** The acceptance criterion is no corrosion rate shall excess 10mdd.

16

Table 2-2 Duplex Stainless Steel ASTM A923 Method C Ferric Chloride Corrosion Test Results,
ASTM A890-5A (6% FeCl3, Base Metal@25C & Weld Metal@22C,24 hrs.)
Material
Code
Condition
Corrosion Rate
P/F***
(mdd**)
ASTM A 890-5A
Heat 1
Solution annealed
2.64
P
ASTM A 890-5A

Heat 1

ASTM A 890-5A

Heat 2

ASTM A 890-5A

Heat 2

ASTM A 890-5A

Heat 3

ASTM A 890-5A

Heat 3

ASTM A 890-5A

Heat 3
CC*
Heat 3
CC*
Alloy2507

ASTM A 890-5A
Alloy 2507
Alloy 2507

Alloy2507
(A-W)

SA
Autogenous welded
Solution annealed

CPT
(C)
65

3.05

45

0.00

50

4.41

40

0.00

65

SA
Autogenous welded
Solution annealed

0.00

45

0.00

50

SA
Autogenous welded
Wrought

3.78

30

0.00

80

0.00

45

SA
Autogenous welded
Solution annealed

Wrought
Autogenous welded

* CC - centrifugal cast
2
* mdd - mg/dm /day
** The acceptance criterion is no corrosion rate shall excess 10mdd.

17

Table 2-3 Duplex Stainless Steel ASTM A923 Method C Ferric Chloride Corrosion Test Results,
ASTM A890-6A (6% FeCl3, Base Metal@25C & Weld Metal@22C,24 hrs.)
Material
Code
Condition
Corrosion Rate
P/F***
(mdd*)
ASTM A 890-6A
Heat 1
Solution annealed
0.00
P
ASTM A 890-6A

Heat 1

ASTM A 890-6A

Heat 2

ASTM A 890-6A

Heat 2

ASTM A 890-6A

Heat 3

ASTM A 890-6A

Heat 3

Zeron 100

Zeron 100

Zeron 100

Zeron 100

SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Wrought
Wrought
Autogenous welded

* mdd - mg/dm /day

*** The acceptance criterion is no corrosion rate shall excess 10mdd.

18

CPT
(C)
65

4.47

55

0.00

70

0.00

45

0.67

55

2.70

40

0.00

65

0.00

30

Table 2-4 Duplex Stainless Steel ASTM A923 Method C Ferric Chloride Corrosion Test Results,
ASTM A890-1B (6% FeCl3, Base Metal@25C & Weld Metal@22C,24 hrs.)
Material
Code
Condition
Corrosion Rate
P/F***
(mdd**)

CPT
(C)

ASTM A 890-1B

Heat 1

Solution annealed

0.00

35

ASTM A 890-1B

Heat 1

16.79

25

ASTM A 890-1B

Heat 2

SA
Autogenous welded
Solution annealed

0.00

40

ASTM A 890-1B

Heat 2

198.02

15

ASTM A 890-1B

Heat 3

SA
Autogenous welded
Solution annealed

3.45

30

ASTM A 890-1B

Heat 3

133.92

15

ASTM A 890-1B

Heat 4

SA
Autogenous welded
Solution annealed

2.87

35

ASTM A 890-1B

Heat 4

184.31

10

Ferralium 255

Ferr. 255

SA
Autogenous welded
Wrought

1.96

45

Ferralium 255

Ferr. 255

Wrought
Autogenous welded

66.39

25

** mdd - mg/dm /day

*** The acceptance criterion is no corrosion rate shall excess 10mdd.

19

Table 2-5 Duplex Stainless Steel ASTM A923 Method C Ferric Chloride Corrosion Test Results,
CD7MCuN (6% FeCl3, Base Metal@25C & Weld Metal@22C,24 hrs.)
Material
Code
Condition
Corrosion Rate
P/F***
(mdd**)
CD7MCuN
Heat 1
Solution Annealed
0.00
P
CD7MCuN

Heat 1

CD7MCuN

Heat 2

CD7MCuN

Heat 2

CD7MCuN-CC

Heat 1
CC*
Heat 1
CC*

CD7MCuN-CC

CPT
(C)
45

SA
Autogenous Welded
Solution Annealed

427.03

0.00

40

SA
Autogenous Welded
Solution Annealed

142.64

15

0.00

50

SA
Autogenous Welded

116.40

15

* CC - centrifugal cast
2
* mdd - mg/dm /day
** The acceptance criterion is no corrosion rate shall excess 10mdd.

20

Table 3-1 Duplex Stainless Steel CPT Test Results, ASTM A890-4A
(ASTM G48, 6 % FeCl3, 24 hrs.)
Material
Heat No.
Condition

CPT (C)

ASTM A 890-4A

Heat 1

As-cast

25

ASTM A 890-4A

Heat 1

15

ASTM A 890-4A

Heat 1

As-cast
Autogenous welded
Solution annealed

ASTM A 890-4A

Heat 1

ASTM A 890-4A

Heat 2

ASTM A 890-4A

Heat 2

ASTM A 890-4A

Heat 3

ASTM A 890-4A

Heat 3

ASTM A 890-4A

Heat 4

ASTM A 890-4A

Heat 4

ASTM A 890-4A

Alloy 2205

Heat 4
CC*
Heat 4
CC*
Alloy 2205

Alloy 2205

Alloy 2205

ASTM A 890-4A

SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Solution annealed

21

30
35
0
50
0
45

SA
Autogenous welded
Solution annealed

20

SA
Autogenous welded
Wrought

15

Wrought
Autogenous welded

* CC - centrifugal cast

40

50

40
25

Table 3-2 Duplex Stainless Steel CPT Test Results, ASTM A890-5A
(ASTM G48, 6 % FeCl3, 24 hrs.)
Material

Heat No.

Condition

CPT (C)

ASTM A 890-5A

Heat 1

As-cast

ASTM A 890-5A

Heat 1

Solution annealed

65

ASTM A 890-5A

Heat 1

45

ASTM A 890-5A

Heat 2

SA
Autogenous welded
Solution annealed

ASTM A 890-5A

Heat 2

ASTM A 890-5A

Heat 3

ASTM A 890-5A

Heat 3

ASTM A 890-5A

Heat 3
CC*
Heat 3
CC*

ASTM A 890-5A

SA
Autogenous welded
Solution annealed

50
40
65

SA
Autogenous welded
Solution annealed

45

SA
Autogenous welded

30

50

Alloy 2507

Alloy2507

Wrought

80

Alloy 2507

Alloy2507

Wrought
Autogenous welded

45

* CC - centrifugal cast

22

Table 3-3 Duplex Stainless Steel CPT Test Results, ASTM A890-6A
(ASTM G48, 6 % FeCl3, 24 hrs.)
Material

Heat No.

Condition

CPT (C)

ASTM A 890-6A

Heat 1

Solution annealed

65

ASTM A 890-6A

Heat 1

55

ASTM A 890-6A

Heat 2

SA
Autogenous welded
Solution annealed

ASTM A 890-6A

Heat 2

ASTM A 890-6A

Heat 3

ASTM A 890-6A

Heat 3

Zeron 100

Zeron 100

Zeron 100

Zeron 100

SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Wrought
Wrought
Autogenous welded

23

70
45
55
40
65
30

Table 3-4 Duplex Stainless Steel CPT Test Results, ASTM A890-1B
(ASTM G48, 6 % FeCl3, 24 hrs.)
Material

Heat No.

Condition

CPT (C)

ASTM A 890-1B

Heat 1

As-cast

15

ASTM A 890-1B

Heat 1

15

ASTM A 890-1B

Heat 1

As-cast
Autogenous welded
Solution annealed

ASTM A 890-1B

Heat 1

ASTM A 890-1B

Heat 2

ASTM A 890-1B

Heat 2

ASTM A 890-1B

Heat 3

ASTM A 890-1B

Heat 3

ASTM A 890-1B

Heat 4

ASTM A 890-1B

Heat 4

Ferralium 255

Ferr. 255

Ferralium 255

Ferr. 255

Ferralium 255

Ferr. 255

SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Solution annealed
SA
Autogenous welded
Solution annealed

24

35
25
40
15
30
15
35

SA
Autogenous welded
Wrought

10

Wrought
Autogenous welded (Ar)
Wrought
Autogenous welded
(Ar + 5%N2)

25

45

30

Table 3-5 Duplex Stainless Steel CPT Test Results, CD7MCuN

(ASTM G48, 6 % FeCl3, 24 hrs.)
Material

Heat No.

Condition

CPT (C)

CD7MCuN

Heat 1

Solution Annealed

45

CD7MCuN

Heat 1

CD7MCuN

Heat 2

SA
Autogenous Welded
Solution Annealed

CD7MCuN

Heat 2

CD7MCuN-CC

Heat 1
CC*
Heat 1
CC*

CD7MCuN-CC

SA
Autogenous Welded
Solution Annealed
SA
Autogenous Welded

* CC - centrifugal cast

25

40
15
50
15

Figure 1-1. Sodium Hydroxide etched structure of ASTM A890-4A (a) As-cast, (b)
SA Casting, (c) Wrought Alloy 2205, 400X
26

Figure 1-2. Sodium Hydroxide etched structure of ASTM A890-5A (a) As-cast, (b)
SA Casting, (c) Wrought Alloy 2507, 400X
27

Figure 1-3. Sodium Hydroxide etched structure of ASTM A890-6A (a) As-cast, (b)
SA Casting, (c) Zeron 100, 400X
28

Figure 1-4. Sodium Hydroxide etched structure of ASTM A890-1B (a) As-cast, (b)
SA Casting, (c) Ferralium 255, 400X
29

(a)

(b)
Figure 2. Microstructure of ASTM A890-4A Heat 1 in the As-cast condition, (a) Base
Metal, 400X, (b) Pitting , 200X, Oxalic
30

(a)

(b)
Figure 3. Microstructure of ASTM A890-4A Heat 1 in the SA condition, (a) Base
Metal, 400X, (b) Pitting , 200X, Oxalic
31

(b)

Figure 4. Microstructure of wrought Alloy 2205, SA, (a) Base Metal, 400X, (b)
Pitting , 200X, Oxalic
32

(a)

(b)

Figure 5. Pitting of autogenous weld on SA ASTM A890-4A Heat 1, (a) 50X (b)
200X, Oxalic
33

34

Figure 6. Toughness of solution annealed duplex stainless steel castings and companion wrought alloys

35

Figure 7. Microstructure of ASTM A890-4A Heat 2 SA, 400X, Oxalic

36