C d F ti f Hi h T t W ld Creep and Fatigue of High Temperature Welds Creep and Fatigue of High Temperature Welds Creep and Fatigue of High Temperature Welds MH H f i b* PE O’D h b SB L b M.H. Hafezi a, b,* , P.E. O’Donoghue b, c, S.B. Leen a, b M.H. Hafezi , P.E. O Donoghue S.B. Leen a Mechanical Engineering College of Engineering and Informatics NUI Galway Ireland a Mechanical Engineering, College of Engineering and Informatics, NUI Galway, Ireland b R I tit t f E i t l M i d E R h NUI G l I l d b Ryan Institute for Environmental, Marine and Energy Research, NUI Galway, Ireland c Civil Engineering, College of Engineering and Informatics, NUI Galway, Ireland * [email protected] [email protected] Next Generation Power Plants Cyclic Plasticity Analysis of Weld Specimen Next Generation Power Plants Cyclic Plasticity Analysis of Weld Specimen 400 f l fl Pl ti 300 (MPa) p : rule flow Plastic 200 tress ( Q b p ) ( ) ( : hardening Isotropic 100 St Strain p r Q b p r ) ( ) ( : hardening Isotropic 0 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 Strain p x c x p 2 : hardening Kinematic -100 p x c x 3 : hardening Kinematic 300 -200 p r x J f ) ( 3 : function Yield 400 -300 y p r x J f ) ( 2 : function Yield -400 n y y x F 1 min ) ( 2 exp mod : model on Optimisati Figure 6 Experimental cyclic i i y i y x F 2 min ) ( 1 : model on Optimisati Figure 6 Experimental cyclic t t i dt f i i 2 1 stress -strain data for service- Figure 2 Multi stub header unit c f f p N : ip relationsh Manson - Coffin aged P91 (BM) at 600°C [4]. Figure 2. Multi-stub header unit f f 2 Figure 1 Moneypoint 915 MW power station; Challenges facing ne t generation 400 Stress (MPa) b) 400 Stress (MPa) ) 150 Figure 1 Moneypoint 915 MW power station; Kilrush Ireland Challenges facing next generation Stress (MPa) b) a) Kilrush, Ireland plants: 200 200 100 Pa) • More flexible operation, as 0 Strain 0 Strain (%) 2-k (MP ) 2 tanh( 2 p c k y 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 0.6 50 ∆σ/2 2 2 renewable energy comes onstream -200 -200 Computer Code Exp [4] Model onstream, Si ifi l hi h 400 400 Computer Code Exp [4] 0 -0.05 0.05 0.15 0.25 0.35 • Significantly higher steam -400 -400 ∆ɛ p /2 (%) Figure 7 Identification of Figure 8 a) Validation of plasticity model against test temperature and pressure Figure 7 Identification of Figure 8 a) Validation of plasticity model against test dt f i d d P91 t 600°C [4] d b) C li conditions 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 ultra supercritical (USC) operation and softening stress-strain response, N = 1 and 60. supercritical (USC) operation, and C fi i ith bi Figure 3 Photograph of a crack observed in a • Co-firing with biomass Table 3 Material parameters [3] plant component and image of a Type IV crack Table 3. Material parameters [3]. plant component and image of a Type IV crack in a welded connection 6.5 mm 2.7 mm 3.25 mm Zone k c γ b Q in a welded connection. Zone k (MPa) c (MPa) γ b Q (MPa) B mm (MPa) (MPa) (MPa) BM 210 166160 1289 0 56 96 A k h ll i th d l t f hi h t t t il d th b t B 25 m BM WM BM 210 166160 1289 0.56 -96 A key challenge is the development of high temperature materials and the subsequent C 3.2 HAZ HAZ 169 121076 649 0.31 -47 prediction of service life and failure. Welded connections represent the weakest part of HAZ 169 121076 649 0.31 47 WM 185 205690 889 11 122 high temperature plant Thermal fatigue and creep failure commonly occurs at such A WM 185 205690 889 1.1 -122 high temperature plant. Thermal fatigue and creep failure commonly occurs at such connections leading to downtime and costly repair at a minimum or loss of life and connections leading to downtime and costly repair, at a minimum, or loss of life and i tl d t i environmental damage, at a maximum. WM WM Specific Aims & Objectives Radial Axial Hoop Equiv Plastic Specific Aims & Objectives Radial stress Axial stress Hoop stress Equiv. stress Plastic Strain stress stress stress stress Strain 1. Calibrate nonlinear creep-plasticity material models for creep-fatigue of welds HAZ 2. Computational analyses of high temperature creep and cyclic plasticity of welds HAZ 3 Creep and fatigue failure prediction for welded high temperature components 3. Creep and fatigue failure prediction for welded, high temperature components BM Figure 9 Elasto-plastic stress distributions for maximum applied strain Creep Analysis of Two-Material Specimen Figure 9 Elasto-plastic stress distributions for maximum applied strain Creep Analysis of Two Material Specimen 550 600 A i lSt 5 25 r=0 600 Axial Stress (MPa) 5 mm 2.5 mm A n cr : equation Norton r0 r=2.75 400 mm t R t ) 1 ( B 500 r=3.25 400 WM BM 5 m r eq : stress Rupture ) 1 ( 1 Pa) 200 2.5 r s (M 200 A r t : life Creep 450 tress 0 ∆ɛp M r t f : life Creep al St 0 -0.004 -0.003 -0.002 -0.001 -1E-17 0.001 0.002 0.003 0.004 M 400 Axia 200 T bl 1 A l td t t f CMV t 640°C [1] 400 -200 Table 1. Accelerated creep constants for CrMoV at 640°C [1]. BM HAZ WM 400 BM WM Zone A (MPa/h) n M χ α 350 -400 WM HAZ Zone A (MPa/h) n M χ α B M t l (BM) 66 10 15 4 3 299 10 13 5 767 03 0 3 6 9 12 Axial Position (mm) 600 Base 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) 66 ×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 0.2639 responses in weld zones. Zone N (cycles) location T bl 4 Radial Zone N f (cycles) location Table 4. Ail H R t Radial stress BM 2103 A Failure life Axial t Hoop t Rupture stress WM 1271 B prediction stress stress Stress BM WM 1271 B HAZ 624 C prediction at 500°C BM HAZ 624 C at 500 C. Conclusions Conclusions WM 1. Significant stress inhomogeneity was predicted in the two-material, uniaxial, creep test specimen, WM with peak stresses along the bi-material interface. 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- 3. 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 2 2 2 WM BM WM BM WM BM WM 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 consistent ss ss 4. High temperature, low-cycle fatigue cracking was predicted in the heat-affected zone, consistent with the test data 1.5 tress 1.5 t Stres 1.5 tress 1.5 t Stres with the test data. 5 Future work will study creep fatigue damage interaction in welded power plant geometries Axial St ivalent Axial St ivalent 5. Future work will study creep-fatigue damage interaction in welded power plant geometries. 1 ized A 1 d Equi 1 ized A 1 d Equi References ormali malized ormali malized References 0.5 No Outer Surface 0.5 Norm Outer Surface 0.5 No Centre-line 0.5 Norm Centre-line 1 Hyde T H and W Sun (1997) Int J Mech Sci 39(8): 885 898 1. Hyde, T. H. and W. Sun (1997), Int J Mech Sci 39(8): 885-898 2 Simo J C and T J R Hughes (1998) Computational Inelasticity Springer NY 0 0 1 2 3 Normalized Axial Position 0 0 1 2 3 Normalized Axial Position 0 0 1 2 3 Normalized Axial Position 0 0 1 2 3 Normalized Axial Position 2. Simo, J. C. and T. J. R. Hughes (1998), Computational Inelasticity, Springer, NY 3 F h t l t b td ASME P V l &Pi i C f P i 2013 Figure 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, 2013 4 Hd CJ t l ASME PVP 2012 Jl 15 19 2012 T t Ot 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) Zone t (hrs) Location Zone t f (hrs) Location The publication has resulted from research conducted with the financial support of Science Foundation BM 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 A Ireland under Grant Number SFI/10/IN.1/I3015. WM 2715 A