Advanced Alloy Design Concepts for High-Temperature Fossil ... · 3 Advanced Alloy Design Concepts...

ORNL is managed by UT-Battelle for the US Department of Energy

DOE Award Number: FEAA114Period of Performance: Oct. 2013 - Sep.2018Presentation: March 22nd, 2017 (in Computational Materials)

Advanced Alloy Design Concepts for High-Temperature Fossil Energy ApplicationsPI: Yukinori Yamamoto Oak Ridge National Laboratory, Oak Ridge, TN 37831E-mail: [email protected]

Co-investigators:Bruce A. PintOak Ridge National Laboratory, Oak Ridge, TN

Sudarsanam Suresh Babu, Benjamin Shassere*, Chih-Hsiang (Sean) KuoUniversity of Tennessee, Knoxville, TN(*Currently at Oak Ridge National Laboratory)

2017 Crosscutting Research Portfolios ReviewPittsburgh, PA, March 20-23, 2017

2 Advanced Alloy Design Concepts for High-temperature Fossil Energy Applications

AcknowledgementsProgram management: Vito Cedro (NETL), Pete Tortorelli, Hiram Rogers (ORNL)

Scientific advice and support: Mike Brady, Muralidharan Govindarajan, Roger Miller, Zhiqian Sun, Donovan Leonard (ORNL), Bernd Kuhn (Forschungszentrum Jülich GmbH, Germany),Kazuhiro Kimura (National Institute for Materials Science, Japan)

Technical support: Cecil Carmichael, Dave Harper, Greg Cox, Dustin Heidel, Kevin Hanson, Daniel Moore, Tom Geer, Victoria Cox, Eric Manneschmidt, Jeremy Moser, Mike Stephens, George Garner, Doug Kyle, Brian Sparks (ORNL)

Research sponsored by the Crosscutting Research Program, Office of Fossil Energy, U.S. Department of Energy


Project Goals and ObjectivesGoals: To identify and apply breakthrough alloy design concepts and strategies for incorporating improved creep strength, environmental compatibility/resistance, and weldability into three classes of alloys (ferritic, austenitic, and Ni-base) intended for use as heat exchanger tubes in fossil-fueled power generation systems at higher temperatures than possible with currently available alloysObjectives: To develop and propose new creep-resistant, “alumina-forming”, cost-effective structural materials with guidance of computational thermodynamic tools• Milestones (FY2017):1. Complete intermediate-term oxidation and creep testing of scale-up heats of “model alloy” (Met)

2. Submit a journal paper summarizing the new FeCrAl alloy design study (In Progress)

3. Initiate computational screening of next generation advanced alumina-forming austenitic and Ni-base alloys for improved strength and corrosion resistance (In Progress)


Presentation Outline• Backgrounds/Motivation:

– Concepts of “Advanced Alloy Design”– High-Cr containing FeCrAl “ferritic” alloy development

• Update on FY16/17– Effect of alloying on Laves-phase solvus and stability– Creep property evaluation– Oxidation/ash-corrosion tests– Scale-up efforts

• Summary • Future Activities


Backgrounds: Advanced Alloy DesignHigh-temp. Strength

Oxidation/Corrosion

https://mts.com/en/products/industry/materials-testing/index.htmhttp://www.ccj-online.com/prioritization-of-issues-improves-hrsg-reliability-performance/`

High-Cr containing FeCrAl ferritic alloy(Fe-30Cr-3Al base, wt/%)

Weldments

Weld

Type IV failure (at fine grained HAZ)

Source: ETD Ltd.

Base(F-M steel)

Strong demands on new high-temperature materials with improved properties for upper limit temperatures higher than that of the materials currently in service;

– High-temperature strength (tensile, creep)– Environmental compatibilities (oxidation, corrosion)– Minimized weld-related issue for final components– RT toughness (Charpy)– Processibility (including microstructure control)– Inexpensive materials cost (raw elemental costs,

process routes, etc.)

6 Advanced Alloy Design Concepts for High-temperature Fossil Energy ApplicationsF/FM steels Austenitics Ni alloys

Relat

ive ra

w m

ater

ial co

st

(x4~6)

(x ~20)

Target Materials/ ApplicationsThree different grades of structural materials that are currently available for use by the US electric utility industry: 1) Ferritic steels for temperatures up to 600 °C, with ferritic-martensitic versions (F-M steels)

having increased strength up to 600-620 °C;

2) Austenitic stainless steels with strength and environmental resistance up to 650 °C; and

3) Ni-base alloys for temperatures > 700 °C.

(CSEF steels: >3.6Mlbs. for piping and boiler tubing)

Material tonnage

Alstom USC and AUSC Power Plants – J. Marion - NTPC/USAID Int. Conf. SC Plants - New Delhi, India, 22 Nov. 2013 – P 8


Why High Cr Containing FeCrAl Ferritic Alloy?• High surface protection in both steam and ash-corrosion environments• Less thermal expansion and high thermal conductivity• Suppress brittle σ-FeCr formation by Al additions• No Type IV failure because of no BCC-FCC transformation during welding

Fe-19Creq-15Nieq

Fe-30Creq

Ref. Welding Research Supplement (1982)

Mean coefficient of thermal expansion

at 750 °C

(BCC-Fe)

(σ-FeCr)

Fe

Cr

Al

Fe-30Cr-3Al

Fe-Cr-Al ternary alloy phase diagram

Ref. ASM international, Ternary alloy phase diagrams

Fe Cr→

Ref. ASM international, Binary alloy phase diagrams

Fe-Cr binary alloy phase diagram

(F-M steels) (fully ferritic alloys)M23C6, MX

‘-Fe (martensite)

-Fe (ferrite)

(*premature failure at HAZ)

Type IV failure*

Gr. 91Weld


What is the Challenge in High Cr Containing FeCrAlFerritic Alloy?• Poor high-temperature strength due to BCC matrix• Rapid grain coarsening causes poor ductility at low temperature

Fe-30Cr-3Al(Rolled at 300°C + Annealed at 1100°C) 500µm

OMNo optimization

(BCC-Fe matrix)

Fe-30Cr-3Al + Nb, Zr(Rolled at 300°C + Annealed at 1200°C)

Fe-30Cr-3Al +W, Nb, Si(Aged at 700°C)

Laves-Fe2Nb

1µm500µm

OM SEM-BSEAfter optimization

http://www.geocities.jp/ohba_lab_ob_page/structure5.html

Fe: Nb:

C14: Laves-Fe2Nb

→ Use alloying additions for GS stability and strengthening (e.g. Nb for Laves-phase formation)


Alloy Development in Progress• 1st series: Fe-30Cr-3Al with (0~2)Nb-(0~0.3)Zr (in wt.%)

– Optimization of thermo-mechanical treatment– Tensile test (RT~800°C)– Oxidation test (800°C, in air + 10%H2O)– Ash corrosion test (700°C, in ash + corrosive gas)– Creep-rupture test (650~700°C, 70~100MPa)

*Used Bird-Mukherjee-Dorn (BMD) model

2 ln

Calc. minimum creep-rate map

Ash-corrosion test at 700°C for 500h

(Fe-30Cr base)1Al-2Nb

(Fe-30Cr base)3Al-2Nb

Ash: 30%Fe2O3-30%Al2O3-30%SiO2-5%Na2SO4-5%K2SO4Gas: 61%CO2-30%H2O-3%O2-0.45%SO2

2μm

TEM-BFI

Laves in matrix

• 2nd series: Fe-30Cr-3Al with (0.5~2)Nb + W, Mo, Ti, and Y– BCC solvus temperature control– Size stability of Lave-phase particle at 700°C– Oxidation/Ash-corrosion resistance – Property evaluation– Scale-up effort


Major Concerns in FY17

• Effect of third element addition on microstructural stability, mechanical properties, and oxidation/ash-corrosion resistance:– Nb, W, Mo, and Ti (Laves-phase forming elements)– Mn, Si, C (simulate engineering alloys with the level of industrial impurities)

• Scale-up efforts of high-Cr FeCrAl alloy


Experimental Procedure• Alloys to be evaluated:

– Fe-30Cr-3Al base with (or without) Nb, Si, W, Mo, Ti, Y, Mn, and C, wt.%

– Used thermodynamic computational tool (JMatPro, v.8-9) for downselection

• Lab-scale heat preparation:– Arc-melt and drop-cast the bar ingots (13 x 25 x 125 mm)

• Thermo-mechanical treatment:– Homogenization, forging, rolling, annealing– Water-quenching

• Microstructure analysis:– OM, SEM

• Property evaluations:– Creep, oxidation, ash-corrosion

Fe-30Cr-3Al-0.2Si base alloys

1Nb

2Nb1Nb-2W

1Nb-2Mo

1Nb-1Ti

BCC-Cr (α-Cr)

LiquidBCC-Fe700ºC

Fe2Nb-Laves

Annealed at 1200°C (SEM-BSE)

10µm

2Nb alloy 1Nb-2W alloy

Laves-Fe2Nb

Hot-forging (ORNL)

25mm

Lab-scale ingot (ORNL)


Impact of “Third Additional Elements” on Microstructure

• Fine particle size maintained even after 10,000h at 700°C

10µm

10,000h@700ºC168h@700ºC 1,000h@700ºC

10µm

Fe-30Cr-3Al-1Nb-2W

Fe-30Cr-3Al-1Nb-1Ti10,000h@700ºC168h@700ºC 1,000h@700ºC

Growth kinetics of Laves phase

50

500

100 1000 10000

Mea

n pa

rtic

le s

ize*

, nm

Aging time at 700°C, h

0.5Nb-2TI1Nb-1Ti1Nb-1.5Mo1Nb-2W2Nb

1Nb-2W

1Nb-1.5Mo

1Nb-1Ti

0.5Nb-2Ti

100

(Fe-30Cr-3Al base)

at 700ºC (initial condition: HR+Ann@1200ºC)

2Nb (1Nb-1Nb)

200

300

400

*assumed the normal distribution


0

5

10

15

20

0 500 1000 1500 2000 2500

Cre

ep s

trai

n, %

Time /h

700°C/70MPa

2Nb

Third Element Addition Was Effective As Expected

0

5

10

15

20

0 500 1000 1500 2000 2500

Cre

ep s

trai

n, %

Time /h

700°C/70MPa

1Nb-2W

1Nb-0.5Ti(2.5 mole %)

(2.8 mole %)(3.3 mole %)

Creep rate: 1.3 x 10-9/s2.5 x 10-9/s4.7 x 10-9/s

BCC-Cr (α-Cr)

LiquidBCC-Fe

Fe2Nb-Laves

2Nb1Nb-2W

1Nb-0.5Ti

SEM-BSE

1μm

PrecipitateFree Zone

• Grain Boundary Zone Strength Factor:Grain boundary precipitate coverage

Width of precipitation free zoneB. Shassere et al. (to be submitted)


1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

0 1 2 3 4

Cre

ep-r

uptu

re li

fe, h

Laves phase at 700ºC, mole%

Model alloys

700ºC/70MPa

0Nb

1Nb

2Nb1Nb-2W

1Nb-0.5Ti

Creep-rupture life vs. Laves phase

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

0 1 2 3 4

Min

. cre

ep ra

te, /

s


Model alloys

700ºC/70MPa

Min. Creep Rate / Creep-rupture Life Depend On Fraction of Laves Phase Precipitates

Min. creep rate vs. Laves phase

(Fe-30Cr-3Al base) (Fe-30Cr-3Al base)

0Nb

1Nb

2Nb1Nb-2W

1Nb-0.5Ti

Creep-rupture life vs. Min. creep-rate


Moving toward Engineering Alloys

• Optimized the combination of Nb, W, Mo, and Ti: – Maximize Laves phase formation combined with reasonably low BCC solvus

temperature (for Laves phase)

• Considerations of industrial quality chemistry:– Mn, Si, and C were intentionally added to simulate commercial steels– P, S, and N still need to be minimized for better weldability and oxidation

resistance


900

1000

1100

1200

1300

0 2 4 6 8

BC

C s

olvu

s, ºC

Additional element, wt.%

Model, Nb1Nb-Mn-Si-C + Nb

(Fe-30Cr-3Al-1Nb base)

Nb + Mn, Si, C

0

1

2

3

4

5

6

7

8

0 2 4 6 8

Lave

s at

700

ºC, m

ole

%


Model, Nb1Nb-Mn-Si-C + Nb

Nb + 0.4Mn, 0.15Si, 0.03C

(Fe-30Cr-3Al-1Nb base)

900

1000

1100

1200

1300

0 2 4 6 8

BC

C s

olvu

s, ºC


Model, Nb1Nb-Mn-Si-C + Nb + Ti + Mo + W

(Fe-30Cr-3Al-1Nb + Mn, Si, C base)

+Ti +Mo +W

+Nb

0

1

2

3

4

5

6

7

8

0 2 4 6 8

Lave

s at

700

ºC, m

ole

%



+Ti+Mo +W

+Nb


0

1

2

3

4

5

6

7

8

900 1000 1100 1200 1300

Lave

s at

700

ºC, m

ole

%

BCC solvus, ºC


+Ti

+Mo

+W+Nb


BCC Solvus Temperature Control

900

1000

1100

1200

1300

0 2 4 6 8

BC

C s

olvu

s, ºC




+Ti +Mo +W

+Nb

0

1

2

3

4

5

6

7

8

0 2 4 6 8

Lave

s at

700

ºC, m

ole

%



+Ti+Mo +W

+Nb


0

1

2

3

4

5

6

7

8

900 1000 1100 1200 1300

Lave

s at

700

ºC, m

ole

%

BCC solvus, ºC


+Ti

+Mo

+W+Nb


• Ti: < 0.3 wt.% for better oxidation resistance• Mo: < 0.5 wt.% to avoid σ-FeCr or χ-FeCrMo formation

0

1

2

3

4

5

6

7

8

900 1000 1100 1200 1300

Lave

s at

700

ºC, m

ole

%

BCC solvus, ºC

Model, Nb1Nb-Mn-Si-C + Nb + Ti + Mo + WEng. 1Nb+W

+Ti

+Mo

+W+Nb


1Nb-6W, Mo, Ti, Mn, C

1Nb-2W-0.5Mo-0.3Ti + Mn, C

BCC solvus700ºC

Phas

e, m

ole

%

Laves-phase


0

5

10

15

20

0 500 1000 1500 2000 2500

Cre

ep s

trai

n, %

Time /h

700ºC/70MPa

2Nb1Nb-2W

1Nb-0.5Ti

Improved Creep Resistance by Increased Volume Fraction of Laves-phase Precipitates

0

5

10

15

20

0 500 1000 1500 2000 2500

Cre

ep s

trai

n, %

Time /h

700ºC/70MPa

2Nb1Nb-2W

1Nb-0.5Ti

1Nb-2W (with Mo, Ti, Mn, C)

4.2 x 10-9/s4.7 x 10-9/s

0

5

10

15

20

0 500 1000 1500 2000 2500

Cre

ep s

trai

n, %

Time /h

700ºC/70MPa

2Nb1Nb-2W

1Nb-0.5Ti



3.9 x 10-10/s4.2 x 10-9/s

10µm

Interrupted after 500h testing

1Nb-2W, aged 1000h@700C

10µm


1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

0 2 4 6 8C

reep

-rup

ture

life

, h


Model alloysEngineering alloys

700ºC/70MPa

1Nb

1Nb-0.5Ti

1Nb-2W2Nb

1Nb-2W, Mo, Ti

1Nb-6W, Mo, Ti

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04C

reep

-rut

pure

life

, h

Min. creep rate, /s

Model alloysEng. Alloys

700ºC/70MPa

1.E-10

1.E-09

1.E-08

1.E-07

0 2 4 6 8

Min

. cre

ep ra

te, /

s


Model alloysEngineering alloys

700ºC/70MPa

Creep-rupture life vs. Laves phase

Min. Creep Rate / Creep-rupture Life Depend On Fraction of Laves Phase Precipitates

Min. creep-rate vs. Laves phase

(Fe-30Cr-3Al base) (Fe-30Cr-3Al base)

1Nb

2Nb

1Nb-2W

1Nb-0.5Ti

1Nb-2W, Mo, Ti

1Nb-6W, Mo, Ti

Creep-rupture life vs. Min. creep-rate


0

0.1

0.2

0.3

0 500 1000 1500 2000 2500

Mas

s ga

in, m

g/cm

2

100h cycle exposure time, h

25Cr-3Al-2Nb

30Cr-3Al-1Nb-0.5Ti

30Cr-3Al-1Nb-2W

30Cr-3Al-2Nb

30Cr-2.6Al-2Nb

9.05x10-6

1.18x10-5

3.32x10-6

6.89x10-6

1.92x10-6

Parabolic rate constant

(mg·cm-2s-0.5 )

Important Role of Al Addition on Oxidation Resistance

• Slow oxidation kinetics indicates protective alumina scale formation

-0.2

0

0.2

0.4

0.6

0.8

1

0 500 1000 1500 2000 2500

Mas

s ga

in, m

g/cm

2


Binary Fe-25Cr

Binary Fe-30Cr

High Cr FeCrAl

Volatarization of chromia scales: 1/2 Cr2O3 + 3/4 O2(g) + H2O(g) = CrO2(OH)2(g) 800ºC, 10% water vapor, 100h cycle


Ash: Al2O3 16.9%, SiO2 22.6%, CaO 0.9%, Fe2O3 7.8%, KOH 1%, TiO2 0.6%, MgO 0.2%, Fe2(SO4)3 19.8%, MgSO4 10.1%, K2SO4 4.8%, Na2SO4 15.1%Gas: Synthetic gas simulating combustion environment in a steam plant (suggested by B&W/EPRI)

Ash-corrosion Tested at 700ºC for 500h

CC05-6AC (#13457)0.70 mg/cm2

CC05-7AC (#13458)0.63 mg/cm2

CC09-3 (#13460)0.68 mg/cm2

CC11-3 (#13463)0.80 mg/cm2

CC13 (#13465)-142.18 mg/cm2

RF25C (#13467)-46.97 mg/cm2

RF30C (#13469)-139.49 mg/cm2

30Cr30Cr-2.6Al-2Nb 30Cr-3Al-2Nb 1Nb-2W 1Nb-0.5Ti 25Cr25Cr-3Al-2Nb

2mm2mm2mm2mm2mm2mm 2mm

30Cr

-2.6A

l-2Nb 30

Cr-3

Al-2

Nb

30Cr

-3Al

-1Nb

-2W

30Cr

-3Al

-1Nb

-0.5T

i

25Cr

-3Al

-2Nb

Fe-3

0Cr

Fe-2

5Cr(Measured from cross section)


Scale-up Efforts (Fe-30Cr-3Al-2Nb-0.2Si-0.12Y)VIM ingot (4” dia.) after HIPing

Forged at 1250ºC

Total ~22”~20”

~8”

Thickness :~0.6”

~22”

~8”

Rolled (and annealed) at 1250ºC

ACWQ


10

100

20000 21000 22000 23000 24000 25000

Cre

ep s

tres

s, M

Pa

LMP (C=20)

30Cr-3Al-2Nb (small heat_WQ)Gr92Gr91100kh-life temperature

550 650600 700100kh-life temperature, °C

Tested at 650-750°C

10

100

20000 21000 22000 23000 24000 25000

Cre

ep s

tres

s, M

Pa

LMP (C=20)

30Cr-3Al-2Nb (small heat_WQ)30Cr-3Al-2Nb (Scale-up_AC)Gr92Gr91100kh-life temperature



~25%

Effect of Cooling Rate after Solution AnnealingAnnealed at 1250ºC+ WQ

Annealed at 1250ºC+ AC

Fe17Y2

(BCC matrix)

Fe17Y2

(BCC matrix)

Fe2Nb

10

100

20000 21000 22000 23000 24000 25000

Cre

ep s

tres

s, M

Pa

LMP (C=20)

30Cr-3Al-2Nb (small heat_WQ)30Cr-3Al-2Nb (Scale-up_AC)Gr92Gr91100kh-life temperatureEng. 1Nb-6W



WQAC


Summary

• Effect of third element additions in Fe-30Cr-3Al base alloy on “microstructural stability” and “various high-temperature properties”:– W, Mo, and Ti additions are;

• Effective to lower the BCC solvus temperature• Detrimental to microstructure stability during creep deformation

– The larger volume fraction of Laves phase precipitate, the better for the creep resistance– Oxidation and ash-corrosion resistance are more sensitive to the amounts Cr and Al (and Nb)

than the others

• Scale-up efforts in progress– Move to engineering alloys (based on 1Nb-6W +Mo, Ti, Mn, and C)– Require improvement of better processibility (against thermal shock, etc.)


Future Activities

• Property evaluation the second scale-up heat:– Screening basic properties (tensile, hardness, microstructure)

– Intermediate/long-term creep-rupture test at or above 700ºC

– Ash-corrosion resistance evaluation at 700ºC

– GTAW screening

• New efforts on alumina-forming austenitic steels and Ni-base alloys– Target the applications in various extreme conditions (coking, metal dusting, sCO2, etc.)

– Communications with industrial partners initiated


Thanks


0

0.1

0.2

0.3

0 500 1000 1500 2000 2500

Mas

s ga

in, m

g/cm

2


25Cr-3Al-2Nb

30Cr-3Al-1Nb-0.5Ti

30Cr-3Al-1Nb-2W

30Cr-3Al-2Nb

30Cr-2.6Al-2Nb

9.05x10-6

1.18x10-5

3.32x10-6

6.89x10-6

1.92x10-6


(mg·cm-2s-0.5 )

Important Role of Al Addition on Oxidation Resistance

• Slow oxidation kinetics indicates protective alumina scale formation

-0.2

0

0.2

0.4

0.6

0.8

1

0 500 1000 1500 2000 2500

Mas

s ga

in, m

g/cm

2


Binary Fe-25Cr

Binary Fe-30Cr

High Cr FeCrAl

Volatarization of chromia scales: 1/2 Cr2O3 + 3/4 O2(g) + H2O(g) = CrO2(OH)2(g)

0

0.1

0.2

0.3

0 500 1000 1500 2000 2500

Mas

s ga

in, m

g/cm

2


*30Cr-3Al-1Nb-2W-Mo, Ti, Mn, Si, C

*30Cr-3Al-1Nb-6W-Mo, Ti, Mn, Si, C

30Cr-3Al-1Nb-2W

30Cr-3Al-2Nb

*Engineering alloys

6.89x10-6

1.93x10-6

4.23x10-5

2.84x10-5


(mg·cm-2·s-0.5 )

800ºC, 10% water vapor, 100h cycle


0

5

10

15

20

0 500 1000 1500

Cre

ep s

trai

n (tr

ue s

tria

n) /%

Time /h

750°C/50MPa

1Nb-2W (w/Mo, Ti, Mn, C)


Higher Temperature Tests In Progress (750 & 800 °C)

0

1

2

3

4

0 500 1000 1500

Cre

ep s

trai

n (tr

ue s

tria

n) /%

Time /h

800°C/30MPa




Scale-up Efforts (Fe-30Cr-3Al-2Nb-0.2Si-0.12Y)VIM ingot (4” dia.) after HIPing

Forged at 1250ºC

Total ~22”

at 1250ºC+ AC

~20”

~8”Thickness :~0.6”

at 1250ºC+ WQ

Thickness :~0.6”

~20”

~8”

at 1000ºC

~26”

~7”

Thickness :~0.6”

Rolledat 800ºC

~10”

Advanced Alloy Design Concepts for High-Temperature Fossil ... · 3 Advanced Alloy Design Concepts...

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