Testing of Additive Manufactured Corrosion- Resistant Alloys ... - DNV GL AM Materials...NACE TM0177...
Transcript of Testing of Additive Manufactured Corrosion- Resistant Alloys ... - DNV GL AM Materials...NACE TM0177...
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DNV GL © 16 October 2018 SAFER, SMARTER, GREENERDNV GL ©
16 October 2018
Testing of Additive Manufactured Corrosion-Resistant Alloys for Oil and Gas Industry
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Liu Cao, Bill Kovacs, Ramgo Thodla
Christopher Taylor
Materials Technology Development Section, Dublin, OH
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DNV GL © 16 October 2018
Additive Manufacture (AM)
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AM or 3D Printing builds three-dimensional solid objects successively layer-by-
layer from digital models.
ASTM F2792
AM Processes
Directed
Energy
Deposition
Powder
Bed Fusion
Materials
Extrusion
Materials
Jetting
Binder
Jetting
Sheet
Lamination
Vat
Photopoly-
merization
Mate
rials
plastic ✔ ✔ ✔ ✔ ✔ ✔
metal ✔ ✔ ✔ ✔
ceramic ✔ ✔
composite ✔ ✔ ✔
otherswax,
photopolymersand paper
resin, liquid
photopolymer
Energy SourceLaser, electron
beam
Laser, electron
or ion beamheating coil
heating coil, UV
lightN/A
Laser,
ultrasonic
UV light, X-
ray or γ-rays
Relevant Terms
LENS, DMD,
LBMD, EBF3,
DLF, LFF, LC,
CMB, IFF
SLS, SLM,
DMLS, DMP,
EBM, SPS,
Laser Cusing
FDM,
FFF,
FLM
Inkjet, PolyJet,
MJM, Aerosol
Jet, ThermoJet
3DP,
LPS,
DSPC
LOM,
UC,
UAM
SL, SLA,
MPSL,
DLP, FTI
Part Durability
Detail Precision
Surface Roughness
Build Speed Slow Slow Medium Medium Fast Fast Medium
Cost High High Low Low Medium Medium Medium
Support No Yes Yes Yes No No Yes
Post-process Yes Yes Minimum Minimum Yes Yes No
High Durability Low
High Surface Roughness Low
Low Detail or Precision High
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DNV GL © 16 October 2018
Benefits & Challenges of AM for O&G Industry
▪ Complexity for free
– Better strength weight ratio
– Fewer components
– Internal channels/lattice
▪ Fast production run
– Ideal for highly customized & low
volume product
▪ Near net shape manufacturing
– Save materials & machining
– Precious metal, high strength
alloys, ceramics
▪ Distributed production
– Simple supply chain
– Low inventory
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Design for build, support structure
Integrity/quality of complex component
Surface finish to remove inferior “skin”
For critical component, mandatory
qualification and/or certification
through the entire AM production chain
Quality control
Safety & reliability
Expensive machine & powder material
Post-fabrication treatment/finish
Trade-off
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DNV GL © 16 October 2018
Major Issues Related to AM in Oil & Gas
▪ Inherently anisotropic properties and intrinsic defects.
▪ Variability within and between samples or build batches.
▪ Post processing is necessary (HIP-hot isostatic pressing, annealing, heat
treatment, surface finish)
– Post processing may also create problems
▪ Proprietary processes not transparent to end-user
▪ AM is not a production route addressed by existing standard, i.e. NACE
MR0175 / ISO 15156-2015.
▪ Do you qualify it as a product or a process or both?
▪ Uncertainties in reliability and material degradation in a long run.
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DNV GL © 16 October 2018
Corrosion Testing of AM CRAs for Oil & Gas
1. 2017 – mechanical, electrochemical and sour testing of AM 17-4PH
stainless steel
2. 2018 – mechanical, electrochemical and sour testing of AM 17-4PH
stainless steel with improved heat treatment
3. 2019 – Susceptibility to hydrogen embrittlement of AM 718 nickel-
based alloy with API 6ACRA specified heat treatment
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Case Studies
W. Kovacs et al, CORROSION/18, paper no. 11212, (Phoenix, AZ: NACE, 2018)
W. Kovacs et al, CORROSION/17, paper no. 9667, (New Orleans, LA: NACE, 2017)
L. Cao et al, CORROSION/19, paper no. 9472, (Houston, TX: NACE, 2019),
submitted
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DNV GL © 16 October 2018
2017 Testing of AM 17-4PH
▪ 17-4PH (UNS S17400) stainless steel from
multiple production routes, heat-treated to
H1150D*
– Wrought (Rod and Plate, H1150D)
– Welded (Plate cut, grooved & GMAW, H1150D
heat treated post welding)
– AM (DMLS + HIP + H1150D) – argon cover gas,
10 ≤ powder size ≤ 55 µm
▪ Testing:
– Mechanical Properties
– Chemistry
– Metallography
– Corrosion tests (CPP, NACE TM0177 Method A)
* NACE heat treatment in old reference.
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2017 Testing of AM 17-4PH
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Macrohardness
Triplicate HRC on each
specimen (different XZ /
YZ planes for AM).
– Poor repeatability on
some AM samples
(and 1 weld)
– 1 AM sample below
minimum spec for
H1150D (24 HRC)
– AM samples on low
end of allowed
hardness range (24-
33 HRC)
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2017 Testing of AM 17-4PH
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Mechanical Properties
▪ All YS ≥ 105 ksi min
▪ AM material have
higher yield, lower
hardness, elongation,
ROA (measured Z-axis
direction only – should
show worst
properties)
▪ AM material has
highest YS/TS ratio,
≤85% desirable as
indicator of austenite
fraction and proper
aging for sour service.
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2017 Testing of AM 17-4PH
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Metallography
a) Rod 3 – 400X (orig. mag.)
10% ammonium persulfate electrolytic etchant b) AM 1-XY-plane – 400X (orig. mag.)
Ralph’s reagent
c) AM 1-XZ plane – 400X (orig. mag.)
Ralph’s reagent d) AM 1-YZ-plane – 400X (orig. mag.)
Ralph’s reagent
50 µm 50 µm
50 µm 50 µm
▪ Chemistry meet
MR0175
specification
▪ Similar grain size
▪ Larger martensite
lath spacing AM
material
▪ More inclusions and
porosity on AM
parts Z-planes (red
circles)
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2017 Testing of AM 17-4PH
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Microhardness
▪ Vickers HV 0.1
(100 g) used to
make small
indents (but
larger than 22
µm)
▪ Hardness: AM
XZ > AM XY >
Rod
▪ Some individual
readings above
328 Hv (with HV
0.1)
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2017 Testing of AM 17-4PH
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Cyclic Potentiodynamic Polarization
OCP for 2 hours,
iApex = 1 mA/cm2, 0.167 mV/s
-100 mVOCP to -100 mVOCP
1E-11 1E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
Po
tentia
l (V
vs.
SH
E)
Current Density (A/cm2)
wrought
AM xy-plane
AM z-axis
17-4PH samples
deaerated 1 M NaCl
room temperature
(a) Wrought (b) AM xy-plane (c) AM z-axis
Figure 4: Images of post-test sample surfaces.
Z
▪ AM-XY similar to wrought – positive hysteresis (localized corrosion), crevice
under gasket
▪ AM-XZ inferior – higher current density, less passive, pitting without crevice
– Passive current density is about 10x of wrought/ AM XY plane
– Expecting galvanic corrosion with itself or wrought material of same grade
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2017 Testing of AM 17-4PH
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NACE TM0177 Method A Uniaxial Tensile Testing
▪ SSC testing in two conditions (both above the MR0175 recommended limit), 90-100% AYS:
– High = 105 psi H2S, 105 psi CO2, pH 3.5, 100 ppm Cl-, 21±3 °C
– Low = 15 psi H2S, pH 3.5, 100 ppm Cl-, 21±3 °C
▪ In both env., wrought/welded survived 30 days, AM failed in
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2017 Testing of AM 17-4PH
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NACE TM0177 Method A for SSC Susceptibility
10X (orig. mag.).
▪ High H2S condition:
o Multiple “dark”
crack initiation sites in edge of
“bright” cracking
regions on each AM specimen
o Presence of secondary cracks
▪ Low H2S condition:
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DNV GL © 16 October 2018
Conclusions of 2017 Testing
▪ AM parts are worse than wrought and welded counterparts by:
– variability in (macro) hardness
– higher YS/TS ratio
– lower ductility in the Z-direction
– local (micro) hardness greater than wrought material
– reduced resistance to localized corrosion when the Z-plane is
exposed.
– greatly reduced sour service performance
▪ Likeliest cause of poorer performance are inhomogeneities
(inclusions, precipitates) and scale/defects (intra-layer defects,
porosity) resulting from the feedstock, fabrication and/or heat
treatment.
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DNV GL © 16 October 2018
2018 Testing of 17-4PH
▪ Test properties and sour performance of 17-4PH (UNS
S17400) Grade 630 H1150D from two build orientations
▪ Trends between standard qualification methods and sour
performance, rapid screening method
▪ Materials:
– 2018 AM (DMLS + HIP + H1150D), Ar/Ar
(atomization/build cover gas), 10 ≤ size ≤ 55 µm
– Z-axis & X-axis build direction, no homogenization
treatment
– Different heat treatment
▪ Testing:
– Chemistry, Mechanical Properties, Hardness,
Metallography
– Corrosion tests (LPR, CPP, NACE TM0177 Method A)
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2018 Testing of 17-4PH
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Macrohardness
▪ Five HRC on each
specimen (XY face of
Z-build, XZ face of X-
build, and XY face of X-
build).
▪ Select “best” and
“worst” sample from
each orientation for
electrochemistry.
▪ Little difference
between test faces of
same blank
▪ Improved repeatability
vs. 2017 AM blanks.
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22018 Testing of 17-4PH
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Mechanical Properties
▪ All ≥ 724 Mpa / 105
ksi min
▪ Minimal Difference
between Z-Build and
X-Build
▪ Some strength has
been sacrificed in
heat treatment in
order to achieve
reduced YS/TS ratio
and improved
elongation and ROA
▪ 2018 materials YS/TS
ratio ≤85%
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2018 Testing of 17-4PH
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Metallography
Z-build X-build
▪ Powder chemistry meet NACE specification, higher Creq and lower Nieq hasten
martensite formation, expected to result in poorer sour performance
▪ 1 μm polish followed by Fry’s reagent and 500X imaging
▪ Similar grain size and microstructure with differing orientations
▪ Typical “wrought” microstructure
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2018 Testing of 17-4PH
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Electrochemical Testing
▪ “Best” and “worst” from hardness repeatability from each build orientation (Z-Build and X-Build)
▪ As-fabricated surface and polished with 800 grit
▪ Masking used to prevent crevices observed in 2017 work
▪ OCP and LPR every 15 minutes for 4 hours, then CPP using 3-electrode (SCE reference) flat cell – 1M NaCl deaerated at 20 °C.
▪ CPP scan from -50 mV at 0.167 mV/s to 1 mA/cm2 reverse apex current density back to -50 mV vs. OCP
N2
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2018 Testing of 17-4PH
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OCP Measurements
0 1 2 3 4-300
-200
-100
0
100
200
0 1 2 3 4-300
-200
-100
0
100
200
X-Build
as-fab, worst, xz-plane polished, worst, xz-plane
as-fab, worst, xy-plane polished, worst, xy-plane
as-fab, best, xz-plane polished, best, xz-plane
as-fab, best, xy-plane polished, best, xy-plane
Co
rro
sio
n P
ote
ntia
l (m
V v
s. S
HE
)
Time (hour)
xz-plane, 2017
xy-plane, 2017
Z-Build
Time (hour)
0 1 2 3 4
0.01
0.1
1
0 1 2 3 4
0.01
0.1
1
X-Build
as-fab, worst, xz-plane polished, worst, xz-plane
as-fab, worst, xy-plane polished, worst, xy-plane
as-fab, best, xz-plane polished, best, xz-plane
as-fab, best, xy-plane polished, best, xy-plane
Corr
osio
n R
ate
(
A/c
m2)
Time (hour)
Z-Build
zx- or xy-plane, 2017
Time (hour)
LPR CR Measurements
▪ As-fab surfaces have more scatter, lower OCP (~200 mV) and higher corrosion rate
▪ On polished surfaces
– “Worst” hardness have lower OCP and higher corrosion rate
– XZ-plane has up to 30-50 mV lower OCP than XY-plane
– X-Build specimens have lower OCP (50-100 mV) and higher corrosion rate than Z-Build
specimens for same surface orientation
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2018 Testing of 17-4PH
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Cyclic Potentiodynamic Polarization: Surface Finish
1E-121E-111E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
AM 17-4PH, xz-plane,
deaerated 1 M NaCl,
room temperature
Po
tentia
l (V
vs.
SH
E)
Current Density (A/cm2)
as-fabricated
polished
1E-121E-111E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Po
tentia
l (V
vs.
SH
E)
Current Density (A/cm2)
as-fabricated
polished
AM 17-4PH, xy-plane,
deaerated 1 M NaCl,
room temperature
▪ As-fabricated did not show typical passive region
▪ As-fabricated surfaces have 150-200 mV lower OCP and ≥ 300 mV lower pitting potential
▪ As-fabricated surface is inferior to polished surface with ~1.5 mm “skin”
depth removed. AM as-fabricated surfaces may be more detrimental to corrosion behavior than the bulk composition/microstructure
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2018 Testing of 17-4PH
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Cyclic Potentiodynamic Polarization
Polished Z-build, XY-plane (build direction out of page)
As-fabricated
▪ Small pitting only on as-fabricated surfaces, vs. significant pitting and crevice attack on polished surface.
▪ Other defects seen on as-polished surfaces indicate higher porosity of 2018 AM vs. 2017 AM (similar features not observed).
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2018 Testing of 17-4PH
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Cyclic Potentiodynamic Polarization
▪ Selective attack on polished specimens gives feather appearance (see SEM
at 50-5000X)
▪ EDS on remaining material shows elevated C, Nb and Cr and decreased
levels of Ni – austenite may be preferentially attacked
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2018 Testing of 17-4PH
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Cyclic Potentiodynamic Polarization: 2017 vs. 2018
▪ Corrosion potential
improved in 2018 by
150 mV on XY plane
and 300 mV on Z-plane
▪ Breakdown potential
improved; suppression
of crevice could be
largely responsible for
this behavior
▪ Growth of localized
corrosion was similar for
both batches of AM
specimens1E-121E-111E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
worst hardness
2017
Po
ten
tial (V
vs. S
HE
)
Current Density (A/cm2)
wrought
AM xy-plane
AM z-plane
17-4PH
z-build AM samples
deaerated 1 M NaCl
room temperature
2018
best hardness
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2018 Testing of 17-4PH
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Cyclic Potentiodynamic Polarization: Build and Orientation
▪ Z-plane or XY-plane of Z-Build specimen has subtly higher OCP and
fewer meta-stable events than X-Build specimens
▪ Could be related to fusion area difference and/or potentially energy
density differences because of incident angle changes.
1E-11 1E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
AM 17-4PH,
polished xz-plane,
deaerated 1 M NaCl,
room temperature
Po
tentia
l (V
vs.
SH
E)
Current Density (A/cm2)
z-build
xy-build
1E-11 1E-10 1E-9 1E-8 1E-7 1E-6 1E-5 1E-4 1E-3 0.01 0.1-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
AM 17-4PH,
polished xy-plane,
deaerated 1 M NaCl,
room temperature
Po
tentia
l (V
vs.
SH
E)
Current Density (A/cm2)
z-build
xy-build
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2018 Testing of 17-4PH
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▪ SSC testing in two conditions (both at the MR0175 recommended limit),
90% AYS:
– A = 0.5 psi H2S, 14 psi CO2, pH 4.5, 100 ppm Cl-, 21±3 °C
– B = 0.5 psi H2S, 14 psi CO2, pH 4.5, 25 ppm Cl-, 21±3 °C
▪ In both env., some specimens survived (one with subcritical flaws) and three
failed specimens had evidence of single initiation.
NACE TM0177 Method A Uniaxial Tensile Testing
10X (orig. mag.)
Single discoloredinitiation site
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2018 Testing of 17-4PH
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NACE TM0177 Method A Uniaxial Tensile Testing
Results Year
Orientation
ppH2S, psi
pH[Cl-], mg/L
Applied Stress,
MPa
Hardness, HRC
YS/TS
Ratio
TTF –Avg. ±
1σ, hours
Result
2017 Z-Build105
3.5 100 82924.6 0.93 ≤ 24 3/3 cracked
15 28.3 0.93 ≤ 24 3/3 cracked
2018
X-Build
0.5 4.5
100 (Env.
A)
683 28.9 0.80416 ±221
1/3 pass2/3 cracked
Z-Build 689 28.4 0.82708 ±
171/3 pass
2/3 cracked
X-Build 25 (Env.
B)
683 28.9 0.80629 ±112
1/3 pass2/3 cracked
Z-Build 689 28.4 0.82540 ±142
3/3 cracked
Triplicate AM UNS S17400 H1150D at 22°C (72°F), 90% AYS
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2018 Testing of 17-4PH
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Scanning Electron Microscopy: CPP vs. NACE Method A
Selective attack on specimen surface is likely initiator of failure in
both CPP and NACE Method A testing.
Fracture Face Overview at 10X (orig. mag.). Image/Location 3-5 at 150X (orig. mag.).
Image/Location 3-5 at 500X (orig. mag.). Image/Location 3-5 at 2500X (orig. mag.).
2017 AM 1 (Z-Build) – SSC Test in
Low H2S, dark site on edge
2018 AM (Z-Build, XY-Plane)
– CPP Test in 1 M NaCl
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DNV GL © 16 October 2018
Conclusions of 2018 Testing
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▪ Small alterations to post-HIP heat treatments had large benefit in performance,
overcoming even inferior powder composition and higher porosity of 2018 AM
vs. 2017 AM.
– Translated to improved corrosion resistance of 2018 AM parts
▪ The 2018 Z-Build and X-Build (both with low YS/TS ratios) can outperform
wrought and welded counterparts with higher YS/TS ratios.
▪ As-fabricated surface had great data scatter, lower corrosion resistance
compared to polished surfaces with 1.5 mm “skin” removed.
▪ Specimens with the best hardness consistency exhibit slightly improved
corrosion resistance.
▪ Similar corrosion resistance seen on XY-plane or Z-plane, although the XY plane
is typically slightly better.
▪ Electrochemical results indicates slightly better corrosion resistance of Z-Build
specimens than X-Build specimens. Inconclusive in NACE Method A testing.
▪ Hardness and electrochemical measurements (OCP and LPR) can be used as
rapid screen methods.
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DNV GL © 16 October 2018
2019 Testing of AM 718
▪ Susceptibility of hydrogen embrittlement (HE) Inconel 718 (UNS
N07718) from two build orientations
▪ Effects of STA on HE of AM 718 with indication of microstructure and
performance, in comparison to wrought 718
▪ Materials:
– AM 718 (PBF + stress relief + HIP + STA per API 6ACRA 140 ksi
designation)
– Z-axis (vertical) & X-axis (horizontal) build directions
▪ Testing:
– Slow strain rate (SSR) tensile test in deaerated 3.5% NaCl under
cathodic protection (CP)
– Static crack growth rate (SCGR) test in deaerated 3.5% NaCl (pH 8.2)
under a variety of applied CP potentials
– Microstructure characterization by SEM, TEM, EBSD
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DNV GL © 16 October 2018
2019 Testing of AM 718
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Horizontal
Vertical
CT specimen
SSR/tensile specimen
AND
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2019 Testing of AM 718
MaterialDNV GL
ID
Solution Annealing
(Temp./Time/Quench medium)
Age Hardening
(Temp./Time/Quench medium)
AM 718 (140 ksi) 2988 1052°C(1) / 1.5h / Water 760°C(2) / 6h / Air
Wrought 718 (120 ksi) 2276 1030°C / 1.5h / Water 780°C / 7h / Air
Wrought 718 (140 ksi) 2625 1030°C / 1.6h / Water 780°C / 6.5h / Air
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Solution Treatment and Ageing (STA)
Rationale of STA for AM 718: maximum allowable solution treatment temperature (not
exceed 1052°C) per API 6ACRA to promote redissolution of ’, ’’ and δ-phase; and as low
as possible ageing temperature (760°C) to minimize δ-phase formation or other
deleterious phases (e.g., Laves).
(wt%) Al Si Ti Cr Mn Fe Co Ni Nb Mo Ta
AM 718 (2988) 0.80 0.38 1.08 19.03 0.60 18.26 0.63 50.60 4.77 3.05 1.5
Wrought 718
120ksi (2276)*0.44 - 0.98 18.4 0.10 18.72 0.21 53.0 4.92 2.89 -
Wrought 718
140ksi (2276)*0.48 - 0.94 18.35 0.11 17.94 0.42 53.5 5.01 3.05 -
Chemical Composition
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2019 Testing of AM 718
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SSR Test Results
AM 718, vertical
AM 718, horizontal
1 day precharging
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2019 Testing of AM 718
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▪ SSR test results of AM 718 under cathodic protection is comparable for
wrought counterparts
Materials ConditionMax
Load, lbUTS, ksi tf, h Total %El %εp %RA
AM 718 (140
ksi), vertical3.5% NaCl + CP 3288 185 122.6 21.9% 16.6% 25.0%
AM 718 (140
ksi), horizontal3.5% NaCl + CP 3262 185 108.6 19.4% 13.7% 22.9%
Wrought 718
(140 ksi)*
Air 3141 178 180.0 32.4% 26.2% 39.2%
3.5% NaCl + CP 2976±5 168±0.3 125.9±0.6 22.7%±0.1 12.5%±3.6 16.0%±4.9
Wrought 718
(120 ksi)*
Air 3191 180 181.2 32.6% 26.0% -
3.5% NaCl + CP 2962±36 167±4 98±18.4 18.1%±3.9 16.6%±0.1 -
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2019 Testing of AM 718
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AM
718,
vert
ical
AM
718,
horizonta
l
Miro-void ductile Intergranular Transgranular w/ slip steps
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2019 Testing of AM 718
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▪ Similar fracture features previously found on wrought 718 140 ksi samples
Grain boundary δ phase precipitate
Miro-void ductile Intergranular Transgranular w/ slip steps
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2019 Testing of AM 718
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SCGR Test Procedure
Kmax (ksi in) Kmin (ksi in) f (Hz) da/dt (mm/s) Da (mm) Comments90 54 0.100000099 4.64E-05 0.00868822 'Beff=0.4344"'
90 54 0.01000001 9.43E-06 0.00382109 '90/10'
90 54 0.000999999 5.44E-06 0.00518067 '900/100'
90 54 0.0001 1.26E-05 0.018705751 '9000s holds'
90 Constant K 1.04E-05 0.008749034 'constant Kmax'
90 Constant K 5.91E-06 0.002072606 'Eapp =-1150mV vs SCE'
90 Constant K 3.45E-06 2.82E-03 'Eapp=-1100mV vs SCE'
90 Constant K 1.88E-06 0.002963693 'Eapp=-1050mV vs SCE'
90 Constant K 6.85E-07 0.002260698 'Eapp=-1000mV vs SCE'
90 Constant K 2.66E-07 1.97E-03 'Eapp=-950mV vs SCE'
90 Constant K 7.37E-08 0.002070495 'Change to -900mV SCE'
90 Constant K 3.67E-09 0.000445623 'Eapp to -850 mV vs SCE'
90 Constant K 1.14E-05 0.005623467 'Eap to -1200mV vs SCE'
90 Constant K 6.50E-06 0.001860668 'Eapp to -1150mV vs SCE'
90 Constant K 4.13E-06 0.002892719 'Eapp to -1100mV vs SCE'
90 Constant K 2.18E-06 0.004440231 'Eapp to -1050mV vs SCE'
90 Constant K 1.27E-06 0.008519321 'Eapp to -1000 mV vs SCE'
90 Constant K 6.22E-07 0.002649823 'Change to -950mV SCE'
90 Constant K 4.20E-07 0.002559372 'Change to -925mV SCE'
90 Constant K 1.39E-07 2.42E-03 'Eapp to -900mVvs SCE'
90 Constant K 5.26E-08 0.000443439 'Change to -875mV SCE'
thold
K max
Time
K
K min , R = 0.5
1h 2.5h 24h
Constan t at
K max
▪ FCGR to SCGR Transition ▪ pH 8.2 maintained by circulating 3.5% NaCl and adding HCl
▪ Parameters used in transition and SCGR Test
thold
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DNV GL © 16 October 2018
2019 Testing of AM 718
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Preliminary SCGR Results ▪ Crack length was monitored by direct current potential
drop (DCPD) method. Voltage
drop was converted to crack
length using Johnson
equation in ASTM E1457.
▪ 2~5 times higher CGR of AM
718 in same environment
under CP (
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DNV GL © 16 October 2018
Conclusions of 2019 AM 718 Testing
▪ Post-fabrication heat treatment (referred to STA process) is equally important for
AM 718 parts to gain higher strength and tune microstructure to meet
performance requirements.
▪ In SSR test, heat-treated AM 718 vertical and horizontal specimens exhibited
similar performance which are comparable to wrought 718.
▪ The fracture surface morphology of AM 718 and wrought 718 SSR specimens was
similar: mixed intergranular and transgranular. The intergranular fracture is
related to the presence of intergranular δ-phase and transgranular surface is
roughed with slip steps.
▪ In SCGR test, AM 718 horizontal specimen showed the same trend found on
wrought 718: crack growth rate increased by decreasing the applied potential
(more negative). However, the magnitude of crack growth rate was 2~5 times
higher than the wrought counterpart at each applied potential except -850 mVSCE,
where hydrogen generation is a rate limiting step.
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DNV GL © 16 October 2018
Summary on AM Work
▪ Columbus lab is active in several AM qualification and fit-for-purpose testing
projects focused on oil and gas upstream industry, Navy and power generation
▪ Developing an understanding of materials is key to successful insertion of AM
parts in critical service
– Proprietary processes is a challenge in understanding processing
– Rapid changes in technology means properties are changing
▪ Post-fabrication heat treatment, i.e. stress relieve, HIP, STA, is critical to control
properties of final AM metal parts, which can be on a par with wrought
counterparts or excel.
▪ Think out of box: tailor traditional metal development for AM
– As results of fast solidification, AM is capable to produce microstructure which is
impossible for traditional casting and forging.
– Alloy powder composition was developed based on traditional manufacturing,
specialized alloy composition could benefit AM processing.
– Heat treatment processes were not optimized for AM parts, fine AM
microstructures need to be treated differently.
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DNV GL © 16 October 2018
Partnership with OSU
▪ AM test parts can be tailored to understand structure-property
relationships
▪ Microscopy
– MicroCT
– Advanced electron microscopy techniques
▪ DNV GL
– FEA analyses
– Lab mechanical testing
– Correlation to microstructure
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DNV GL © 16 October 2018
CHALLENGE
SOLUTION VALUE
BENEFITS
Contact: Region: JIP I.D.:
JIP
Sour Service Performance of Additive Manufactured UNS N07718
42
Additive Manufacturing (AM) presents new opportunities and potential pitfalls to the Oil and Gas Market. Currently, additive manufacturing is not a production route addressed by NACE MR0175 / ISO 15156-2015.
Determining appropriate production techniques and screening methods to identify specific processes, batches or parts that resist environmentally assisted cracking (EAC) in sour service is critical to the
future of AM in Oil and Gas Exploration and Production Environments. Understanding the risks associated the incorporation of AM will be vital to determine the qualification processes needed for success.
(1) Identify and work with stakeholders to evaluate issues.
(2) Obtain components and characterize chemistry, microstructure and
mechanical properties.
(3) Sour service testing in DNV GL’s world-class H2S materials testing facility
(4) Analyze correlations and iterate production/testing to refine process and
understand how AM parts differ from conventional manufacture
Benefits to market will include:
AM sour-service performance from multiple vendors, correlation of
process variables, NDT and microstructure with sour performance,
informed risk-assessment regarding use of AM in oil and gas industry
Knowledge base of build-process/chemistry-
microstructure/mechanical performance
characteristics
Sour service evaluation and comparison to
wrought and welds
Process refinement to improve performance
[email protected] / 614 787 8995
[email protected] / 614 734 6121
North America 2017-XXX
Example Benefits of AM:
Reduce Development Time / Downtime
Enable new technologies
Manufacture and repair on-demand and on-location
(e.g. platforms)
Manufacture complex shapes without
machining facilities
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DNV GL © 16 October 2018
The AM Performance Pipeline
Build Processing Microstructure Performance
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DNV GL © 16 October 2018
Ex: Oil and Gas for Sour Service and Seawater CP environments
NACE MR0175
Material/Composition
Production Process
For AM, knowledge-base needs to be generated for the AM performance pipeline
44
Seawater CP
Material/Composition
Production Process
Microstructure influences performance, H embrittlement, etc.
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DNV GL © 16 October 2018
AM Process Variables
AM
• Orientation
• Build parameters
• Microstructural Features
• Porosity
• …
Vs. Conventional Forging
45
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DNV GL © 16 October 2018
AM and OG Stakeholders
AM
OG Asset Owners
Operators
OEMs
AM Vendors
Powder Manufacturers
3rd Parties, Regulators,
SMEs
46
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DNV GL © 16 October 2018
Seifi’s Path towards Qualification
Barr
iers • Presence of
Defects
• Anisotropy
• Surface Roughness
• Similitude between coupons and actual parts
ND
T • X-ray CT• Ultrasonic
testing
• Eddy current
• Optical examination
Develo
pm
ent Path • AM standards
across production chain
• Fracture/fatigue testing
• NDT capability, e.g.watermarking
• In situ process monitoring
• Microstructure/ Residual Stress/
47
Seifi, et al. 2017: "Progress Towards Metal Additive
Manufacturing Standardization to Support Qualification and
Certification," JOM, 69, 439-455 (2017)
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DNV GL © 16 October 2018
Prior Experience with AM Microstructures and Performance
Idell 2016
Continuous melt/resolidification process
Microsegregation
Delta-phase microplatelets
Voids + high strain fields
Novel HT required
Keller 2017
Models: Finite Element, Phase Field, CALPHAD
Microstructure Prediction
Validate against in-process, post-build and XRD
Kovacs 2016-2017
17-4 PH: Chemical, Mechanical, Microstructure,
Electrochemistry
AM more prone to corrosion, failed NACE Method A (SSC)
< 24 hours
Iterating on HT and tests led to acceptable performance,
~wrought
48
Idell, et al. 2016: JOM 68:950-959 (2016)Keller, et al. 2017: Acta Materialia. 149, 244-253 (2017)
Kovacs, et al. 2017: NACE Corrosion 2017, New Orleans, LA: Paper No. 9667.Kovacs, et al. 2018: NACE Corrosion 2018, Phoenix, AZ: Paper No. 11212.
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DNV GL © 16 October 2018
JIP Structure
Identify and Assemble Stakeholders
Identify Materials and Environments of Interest
Identify Microstructure/Performance
Test Matrix
Iterate on Production, Processing and Testing
Encapsulate Knowledge Base, Next Steps (=> Qualification Cmte)
49
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DNV GL © 16 October 2018
Proposed JIP Flow
50
Phase 0 – Select Materials – Wrought/AM 1/ AM 2
Note: AM material to be donated by participants
Phase 1 – Microstructural Characterization
• Advanced SEM
• Grains size/dist/ppt/GB characterization
• TEM if needed
Phase 2 – Mechanicals Per API 6A CRA
• Tensiles/Charpy/CTODs
Phase 3 – Environmental Testing
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DNV GL © 16 October 2018
Proposed JIP Flow
51
Phase 3 – Environmental Testing
Sour Service Testing
Preliminary Testing – 4 point bends (Level V)
• Wrought/AM1/AM2
• Multiple Orientations
• Based on results perform limited SSR Testing
• 6 SSR in Environment
Seawater + CP Testing
FCGR/SCGR testing on AM1/AM2 to compare
with wrought data
• Wrought data donated by DNV GL
• Post Test Characterization to understand
crack morphology and interaction with
microstructure
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DNV GL © 16 October 2018
Flow and Details
▪ Summer 2018: Finalize memberships
▪ Fall 2018
– Phase 0 Stakeholders donate components for testing
– Phase 1 Microstructure characterization
– Phase 2 Mechanical evaluation
– Decision point #1
▪ Spring 2019
– Phase 3a/b: First-wave of exposure testing (seawater CP or sour)
– Microscopy and evaluation
– Decision point #2 (3a/3b may be in parallel)
▪ Fall 2019
– Sour service testing
– -Four point bend testing in various orientations
– SSR of select
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Membership Fee:
• 30k + Donated AM materials
Members/Invites:
• Arconic
• Baker Hughes GE
• Chevron
• Carpenter
• Dresser-Rand/Siemens
• GE Additive tentative
• Matheson tentative
• Technip/FMC
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DNV GL © 16 October 2018
SAFER, SMARTER, GREENER
www.dnvgl.com
The trademarks DNV GL®, DNV®, the Horizon Graphic and Det Norske Veritas®
are the properties of companies in the Det Norske Veritas group. All rights reserved.
53
Liu Cao Chris Taylor
[email protected] [email protected]
614-761-6993 614-787-8995
mailto:[email protected]