Upload
duncan
View
33
Download
0
Tags:
Embed Size (px)
DESCRIPTION
R.J Kurtz 1 & U.S. Fusion Materials Scientists 1 Pacific Northwest National Laboratory Fusion Nuclear Science & Technology Meeting August 18 – 20, 2009 University of California Los Angeles. Recent Progress on Ferritic Alloys for Fusion Structural Applications. - PowerPoint PPT Presentation
Citation preview
Recent Progress on Ferritic Alloys Recent Progress on Ferritic Alloys for Fusion Structural Applicationsfor Fusion Structural Applications
R.J Kurtz1 & U.S. Fusion Materials Scientists
1Pacific Northwest National Laboratory
Fusion Nuclear Science & Technology MeetingAugust 18 – 20, 2009University of California Los Angeles
Irradiation Hardening of Eurofer97 at Irradiation Hardening of Eurofer97 at 300 - 336°C300 - 336°C
€
Δσ =Δσys 1−exp−dpadpa0( )[ ]p
€
k=Δσys / dpa0
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60 70 80
E97-1, 300°CE97-2, 300°C325°C330°C332°C336°C
, Dose dpa
300° Fit to C data only
Fit to all data
Hardening coefficient:
Lucon & Vandermeulen / SCK•CEN-BLG-1042 Rev.(1) (2007)
-100
0
100
200
300
400
500
0 100 200 300 400 500 600
Spaetig et al. / ICFRM-13
Rensman, ICFRM-13
Lucon & Vandermeulen
Yamamoto et al. / JNM 2006
Ttest
= Tirr
, °C
Protons
The observation of a shape invariant master KJc(T-To) curve (MC) allows efficient fracture testing in the cleavage transition with a limited number of small specimens.
ΔTo = ΔTirr + ΔTdyn + ΔTstruc + Δtmarg
Requires size and geometry adjustments for constraint loss and statistical size effects - new methods are being developed.
T(ºC)T
o(1) T
o(2)
T-To(ºC)0
Kor
c.
0
100
200
300
400
500
-200 -150 -100 -50 0 50 100 150T - T
o (ºC)
a.
Master Curve and Small SpecimensMaster Curve and Small Specimens
Impact of He-Rich Environment on Impact of He-Rich Environment on Neutron Irradiated MaterialsNeutron Irradiated Materials
A unique aspect of the DT fusion environment is substantial production of gaseous transmutants such as He and H.
Accumulation of He can have major consequences for the integrity of fusion structures such as:
− Loss of high-temperature creep strength.
− Increased swelling and irradiation creep at intermediate temperatures.
− Potential for loss of ductility and fracture toughness at low temperatures.
Grain boundary
1
10
100
1000
Un-implanted 200 appm He
Schroeder and Batflasky, 1983
0
50
100
150
200
250
300
0 100 200 300 400
Δσy ( )MPa
ΔT0 = 0.58 Δσ
y
F82H (IEA)T
irr = 250 ~ 300 ºC
c.
Relation Between Relation Between ΔΔTToo and and ΔσΔσyy for for F82H and Effect of High HeF82H and Effect of High He
Yamamoto et al. / Journal of Nuclear Materials 356 (2006) 27.
Ductile-to-Brittle Transition Ductile-to-Brittle Transition Temperature Shifts – Effect of HeTemperature Shifts – Effect of He
Ductile
Brittle
T. Yamamoto, Y. Dai, G.R. Odette, et al, Trans. American Nuclear Society 98 (2008) 1111.
€
ΔTc
€
ΔTc =CcΔσ y =CcΔσ ys 1− exp −dpa −dpa0( )[ ]1
2
€
Cc = 0.4 He < 500
Cc = 0.4 + 0.0007(He − 500) 500 < He < 1500
Cc =1.1°C/MPa He > 1500
0
200
400
600
800
1000
0 50 100 150 200dpa
neutron only
10 ( / )appmHe dpa
Cc ≤ 1.1
Fusion Reactor Conditions
0
50
100
150
200
250
300
350
400
450
22000 24000 26000 28000 30000 32000 34000 36000
NFA 12YWT
NFA MA957
9Cr-WMoVNb Steel
LMP T(K)[25 + log10t(h)]
Str
ess
(M
Pa)
900°C, 1104h
800°C, 14235h
800°C, 817h
650°C, 13000h
600°C, 17000h
650°C, 1080h650°C16h
650°C>72h
825°C, 39024h(in test)
800°C, 38555h(failed recently)
Thermal Creep of NFAs: MA957 and Thermal Creep of NFAs: MA957 and 12YWT12YWT
D.T. Hoelzer, et al 2008
G.R. Odette, et al 2008
NFA = Nanocomposited ferritic alloy
Fe – (12-14)Cr – Ti – Y2O3
• Remarkable thermal stability @ ≥ 1150°C:
r(ta,Ta) - ro ≈ ro[2.4x1027exp(-880x103/RT) - 1]1/5
• Minor softening 104 h @1000°C
0
1
2
3
4
5
6
7
1100 1150 1200 1250 1300 1350 1400 1450
Temperature (oC)
9 Hour MA957 Anneal
1
AE Aged
Aged
20nm
AE
0
50
100
150
200
250
300
350
0 2000 4000 6000 8000 1 104 1.2 104
800°C850°C900°C950°C1000°C
Aging Time (h)
1000°C, 11 kh
Y-Ti-O Nanocluster Thermal StabilityY-Ti-O Nanocluster Thermal Stability
No DBTT Shift Observed in 14YWT No DBTT Shift Observed in 14YWT After Irradiation at 300After Irradiation at 300ooC to ~1.5 dpaC to ~1.5 dpa
D.A. McClintock et al., ICFRM-13C. Petersen et al., 2005
He Bubble Distribution in Irradiated He Bubble Distribution in Irradiated F82H mod.3 (500F82H mod.3 (500°C, 9 dpa, 380 appm He)°C, 9 dpa, 380 appm He)
He bubbles observed throughout foil, found on low angle boundaries and precipitate interfaces
Slightly broader size range, from 0.5 to ~7 nm Density is ~1.0 x 1023 m-3, avg. size is 1.7
G.R. Odette, P. Miao, T. Yamamoto, et al, Trans. American Nuclear Society 98 (2008) 1148.
He Bubble Distribution in Irradiated He Bubble Distribution in Irradiated MA957 CW (500MA957 CW (500°C, 9 dpa, 380 appm He)°C, 9 dpa, 380 appm He)
He bubbles observed throughout foil, narrow size distribution of small bubbles forming on Y-Ti-O nano-features.
Boundaries appear to be protected from bubble formation Density is ~3 x 1023 m-3, avg. size is ~1 nm
G.R. Odette, P. Miao, T. Yamamoto, et al, Trans. American Nuclear Society 98 (2008) 1148.
Helium Bubble Size and Number Helium Bubble Size and Number Density at 500°C, 380 appm He/9 dpaDensity at 500°C, 380 appm He/9 dpa
MA957
F82H Eurofer97
•Grain aspect ratio ranges from 5:1 to 10:1•Extrusion direction strong but brittle.
0
50
100
150
-200 -100 0 100 200
LR
LR(ductile)
CL
CL(ductile)
T (ºC)
Grain Aspect RatioGrain Aspect Ratio
Low-temperature fracture toughness• ODS alloys are known to have high DBTT and low upper shelf energy – strengthening by
nanoclusters may exacerbate this problem.• Reduce anisotropic properties associated with high texture or GAR.
Joining• Historically a significant problem with ODS alloys, but maybe more difficult due to the
structure of the nanoclusters.• Friction stir welding shows potential.
• Stability of nanoclusters during irradiation (nuclear applications)• Most studies are based on ODS ferritic alloys containing coarser oxide phases, not
nanoclusters.• Little or no information on structural stability of nanoclusters (creep properties, enhancing
recombination of point defects, or He management.
Critical Issus for NFA - ICritical Issus for NFA - I
Scale-up technology• Current knowledge of processing conditions and reproducibility of several small
heats of 14YWT favor scale-up to larger heats.• Must partner with industry.• Fabrication experience for NFA is not extensive.
Cost• Modifications in the mechanical alloying approach.• Alternative processing to mechanical alloying – thermo-mechanical treatment
approaches preferable.
Critical Issus for NFA - IICritical Issus for NFA - II