C d F ti f Hi h T t W ldCreep and Fatigue of High Temperature WeldsCreep and Fatigue of High Temperature WeldsCreep and Fatigue of High Temperature WeldsM H H f i b * P E O’D h b S B L bM.H. Hafezi a, b,*, P.E. O’Donoghue b, c, S.B. Leen a, bM.H. Hafezi , P.E. O Donoghue S.B. Leen

aMechanical Engineering College of Engineering and Informatics NUI Galway IrelandaMechanical Engineering, College of Engineering and Informatics, NUI Galway, IrelandbR I tit t f E i t l M i d E R h NUI G l I l dbRyan Institute for Environmental, Marine and Energy Research, NUI Galway, Ireland

cCivil Engineering, College of Engineering and Informatics, NUI Galway, Irelandg g, g g g , y,*m.hafezi1@nuigalway.iem.hafezi1@nuigalway.ie

Next Generation Power Plants Cyclic Plasticity Analysis of Weld SpecimenNext Generation Power Plants Cyclic Plasticity Analysis of Weld Specimen400f

lflPl ti 300

(MP

a)

fp

:ruleflow Plastic 200

tres

s (

Qb

p )()(:hardeningIsotropic 100

St

Strain

prQbpr )()( :hardeningIsotropic 0

-0.6 -0.4 -0.2 0 0.2 0.4 0.6

Strain

pxcx p 2

:hardeningKinematic -100pxcx p 3

: hardeningKinematic

300

-200

prxJf )(3

:functionYield400

-300 yprxJf )(2

:function Yield-400

nyyxF 1 min)(

2expmod:modelonOptimisati

Figure 6 Experimental cyclic

i iyiyxF 2

min)(1

p :model onOptimisatiFigure 6 Experimental cyclic t t i d t f i

i

2 1

stress -strain data for service-Figure 2 Multi stub header unit cff

p N

: iprelationsh Manson-Coffinaged P91 (BM) at 600°C [4]. Figure 2. Multi-stub header unit ff2

pg ( ) [ ]

Figure 1 Moneypoint 915 MW power station; Challenges facing ne t generation400 Stress (MPa)

b)400 Stress (MPa)

)150Figure 1 Moneypoint 915 MW power station;

Kilrush IrelandChallenges facing next generation Stress (MPa)

b)( )

a)Kilrush, Ireland plants: 200200

100

Pa)

• More flexible operation, as 0Strain

0Strain (%)

2-k

(MP

)2

tanh(2

pcky More flexible operation, as renewable energy comes

0-0.005 -0.003 -0.001 0.001 0.003 0.005

0-0.6 -0.4 -0.2 0 0.2 0.4 0.650∆

σ/2

)2

(2

y

renewable energy comes onstream

-200-200Computer Code

Exp [4]

Modelonstream,Si ifi l hi h 400400

Computer Code

Exp [4]0

-0.05 0.05 0.15 0.25 0.35

• Significantly higher steam -400-4000 05 0 05 0 5 0 5 0 35

∆ɛp/2 (%)

Figure 7 Identification of Figure 8 a) Validation of plasticity model against testtemperature and pressure Figure 7 Identification of Figure 8 a) Validation of plasticity model against test d t f i d d P91 t 600°C [4] d b) C li

p pconditions e g for ultra- material parameters k , c, γ data for serviced-aged P91 at 600°C [4], and b) Cyclic conditions, e.g. for ultrasupercritical (USC) operation and softening stress-strain response, N = 1 and 60.supercritical (USC) operation, and C fi i ith bi

g p ,Figure 3 Photograph of a crack observed in a • Co-firing with biomass

Table 3 Material parameters [3]g g p

plant component and image of a Type IV crackTable 3. Material parameters [3].

plant component and image of a Type IV crackin a welded connection 6.5 mm 2.7 mm 3.25 mm Zone k c γ b Qin a welded connection. Zone k

(MPa)c

(MPa)γ b Q

(MPa)B

mm (MPa) (MPa) (MPa)

BM 210 166160 1289 0 56 96A k h ll i th d l t f hi h t t t i l d th b tB

25 mBMWM BM 210 166160 1289 0.56 -96A key challenge is the development of high temperature materials and the subsequent C

3.2HAZ HAZ 169 121076 649 0.31 -47prediction of service life and failure. Welded connections represent the weakest part of HAZ 169 121076 649 0.31 47

WM 185 205690 889 1 1 122

p p phigh temperature plant Thermal fatigue and creep failure commonly occurs at such A

WM 185 205690 889 1.1 -122high temperature plant. Thermal fatigue and creep failure commonly occurs at suchconnections leading to downtime and costly repair at a minimum or loss of life andconnections leading to downtime and costly repair, at a minimum, or loss of life and

i t l d t ienvironmental damage, at a maximum.

WMWM

Specific Aims & Objectives Radial Axial Hoop Equiv PlasticSpecific Aims & Objectives Radial stress

Axial stress

Hoop stress

Equiv. stress

Plastic Strain

p j stress stress stress stress Strain

1. Calibrate nonlinear creep-plasticity material models for creep-fatigue of weldsHAZ

2. Computational analyses of high temperature creep and cyclic plasticity of weldsHAZ

Co putat o a a a yses o g te pe atu e c eep a d cyc c p ast c ty o e ds3 Creep and fatigue failure prediction for welded high temperature components3. Creep and fatigue failure prediction for welded, high temperature components

BM

Figure 9 Elasto-plastic stress distributions for maximum applied strainCreep Analysis of Two-Material Specimen Figure 9 Elasto-plastic stress distributions for maximum applied strainCreep Analysis of Two Material Specimen 550

600 A i l St

5 2 5 r=0

600 Axial Stress (MPa)

5 mm 2.5 mm A ncr :equation Norton r 0

r=2.75400

mm

tR t

equa oo o

)1(B 500 r=3.25

400

WMBM 5 m r eq :stress Rupture )1(1 P

a)

200

2.5 r q

s (M

200

A rt:lifeCreep

450

tres

s

0∆ɛp

Mrt f :life Creep

al S

t0-0.004 -0.003 -0.002 -0.001 -1E-17 0.001 0.002 0.003 0.004Mf

400

Axi

a

200

T bl 1 A l t d t t f C M V t 640°C [1]

400-200

Table 1. Accelerated creep constants for CrMoV at 640°C [1]. BM HAZ WM400

BM

WM

Zone A (MPa/h) n M χ α 350

-400 WM

HAZZone A (MPa/h) n M χ α

B M t l (BM) 6 6 10 15 4 3 299 10 13 5 767 0 30 3 6 9 12

Axial Position (mm)600Base Metal (BM) 6.6 ×10-15 4 3.299 ×10-13 5.767 0.3 Axial Position (mm)

-600

Figure 10 Sample local stress-strain Figure 11 FE-predicted axial stress distributions.Weld Material WM) 6 6 ×10-14 4 4 141×10-12 4 8496 0 2639 Figure 10 Sample local stress strain responses in weld zones

Figure 11 FE predicted axial stress distributions. Weld Material WM) 6.6 ×10 4 4.141×10 4.8496 0.2639responses in weld zones.

Zone N (cycles) locationT bl 4Radial

Zone Nf (cycles) location Table 4. A i l H R tRadial

stressBM 2103 AFailure life Axial

tHoopt

Rupture stress

WM 1271 Bpredictionstress stress StressBM WM 1271 B

HAZ 624 C

prediction at 500°C

BM

HAZ 624 Cat 500 C.

ConclusionsConclusionsWM

1. Significant stress inhomogeneity was predicted in the two-material, uniaxial, creep test specimen, WM

g g y p , , p p ,with peak stresses along the bi-material interface.p g

2. Creep rupture was predicted in the base metal at the interface on the outer surface.Figure 4 Creep stress contour plots. 2. Creep rupture was predicted in the base metal at the interface on the outer surface. 3. A rate–independent, cyclic plasticity material model was calibrated against strain-controlled three-

g p p3. A rate independent, cyclic plasticity material model was calibrated against strain controlled three

material uniaxial test data based on high temperature tests at NUI Galway [3]2 22 2WM BM WM BM WM BMWM BM

material uniaxial test data, based on high temperature tests at NUI Galway [3].4 High temperature low-cycle fatigue cracking was predicted in the heat-affected zone consistentss ss

4. High temperature, low-cycle fatigue cracking was predicted in the heat-affected zone, consistent with the test data

1.5

tres

s 1.5

t S

tres1.5

tres

s 1.5

t S

tres

with the test data. 5 Future work will study creep fatigue damage interaction in welded power plant geometriesA

xial

St

ival

ent

Axi

al S

t

ival

ent

5. Future work will study creep-fatigue damage interaction in welded power plant geometries. 1

ized

A 1

d E

qu

i

1

ized

A 1

d E

qu

i

References orm

ali

mal

ized

orm

ali

mal

ized

References 0.5No

Outer Surface

0.5

No

rm Outer Surface0.5No

Centre-line0.5

No

rm Centre-line

1 Hyde T H and W Sun (1997) Int J Mech Sci 39(8): 885 8981. Hyde, T. H. and W. Sun (1997), Int J Mech Sci 39(8): 885-8982 Simo J C and T J R Hughes (1998) Computational Inelasticity Springer NY

00 1 2 3

Normalized Axial Position

00 1 2 3

Normalized Axial Position

00 1 2 3

Normalized Axial Position

00 1 2 3

Normalized Axial Position 2. Simo, J. C. and T. J. R. Hughes (1998), Computational Inelasticity, Springer, NY3 F h t l t b t d ASME P V l & Pi i C f P i 2013Figure 5 Steady state creep stress distributions in two material specimen

Normalized Axial Position Normalized Axial Position Normalized Axial Position Normalized Axial Position

3. Farragher et al., to be presented ASME Pressure Vessels & Piping Conference, Paris, 20134 H d CJ t l ASME PVP 2012 J l 15 19 2012 T t O t i C d

Figure 5 Steady-state creep stress distributions in two-material specimen.4. Hyde, CJ et al., ASME PVP-2012, July 15-19, 2012, Toronto, Ontario, Canada.Table 2. Failure time prediction (accelerated) p ( )

Zone t (hrs) LocationZone tf (hrs) Location The publication has resulted from research conducted with the financial support of Science FoundationBM 166 B The publication has resulted from research conducted with the financial support of Science Foundation Ireland under Grant Number SFI/10/IN 1/I3015

WM 2715 AIreland under Grant Number SFI/10/IN.1/I3015.

WM 2715 A