30.10.2009 1

IRRADIATION EMBRITTLEMENT CHARACTERIZATION OF THE EUROFER

97 MATERIAL

M. Kytka, M. Brumovsky

and M. FalcnikNuclear Research Institute Rez plc,

Vltavska 130, 250 68 Rez near Prague, Czech Republic

30.10.2009 2

Introduction

The paper summarizes results of irradiation embrittlement

study of EUROFER 97 material that has been proposed as one candidate for future GEN IV reactors.

Test specimens were manufactured from base metal EUROFER 97 as well as from weld metal and tested in initial unirradiated

condition and also after irradiation to reach approx. 2.5 dpa

.

Sub-sized TPB (3x4 mm) specimens were tested to determine static and dynamic fracture toughness.

The main objective: comparison of unirradiated

and irradiated properties as well as changes in transition temperature shifts of these material parameters.

The investigation has been performed in the frame of EFDA project on „Tritium Breeding and Materials“, Task TW2.

30.10.2009 3

Material and Specimens

Micro-TPB samples (W=4mm, B=3mm) were prepared by machining from plates of 14 mm thickness. Static fracture toughness specimens have been side grooved.

Materials:– BASE METAL: Reduced activation martensitic

steel EUROFER 97

(steel plates of 300x300x14mm).– WELD METAL: A weld joint was prepared from two plates

14x90x300mm by TIG method in CEA Saclay.

Tab. 1 The chemical composition of EUROFER 97 in w%:C Mn Si P S Cu Ni Cr Ti Zr

0.11 0.47 0.040 0.005 0.004 0.0016 0.022 8.82 0.005 <0.005

B As O N V W Mo Ta Nb Co<0.001 <0.005 0.001 0.0034 0.20 1.09 <0.005 <0.005 0.0016 0.006

30.10.2009 4

Irradiation

1

Material specimens were irradiated in the Chouca

rig (irradiation rig with a controlled temperature and inert gas) in the core of the LVR-15 experimental reactor in the Nuclear Research Institute Rez

plc. for 8 irradiation cycles (21 days each) at max. 235

°C.

Neutron fluence

was equivalent to approx. 2.5 dpa

(1.5 x 1021

n.m-2, E >1 MeV).

30.10.2009 5

Irradiation 2

Fig. 1 Average neutron fluences (individual blocks of specimens inthe irradiation rig)

0,0

0,5

1,0

1,5

2,0

2,5

3,0

0 100 200 300 400Position (mm)

Neu

tron

fluen

ce (1

0 21n.

m -2

)E > 0.5 MeVE > 1. MeV

Blocks of specimens forstatic/dynamic FT

30.10.2009 6

Procedure

1

Testing end evaluation of the results has been performed in accord with:

Dynamic fracture toughness– EN 10045-1 Metallic materials-Charpy

impact test-Part 1

– ISO 14556 Steel-Charpy-V notch pendulum impact test-Instrumented test

– ESIS TC5 Proposed standard method for instrumented impact testing of sub-sized Charpy-V notch specimen of steels (Draft 10)

– ASTM E 1921-05 (obtained reference transition temperatures are not in compliance with the requirements of the method)

Static fracture toughness– ASTM E 1820-01– ASTM E 1921-05 (invalid reference temperature To)– Additional evaluation of J-R

test in upper shelf in agreement with CSN

420347 (Czech national testing method) and ESIS P2/91D procedure

30.10.2009 7

Procedure

2

Transition temperatures :

Static and dynamic fracture toughness

– Transition temperature T100

at KJC

=100 MPa.m1/2

– Reference temperature To

(ASTM E 1921-05)

TaJC eaKK 1

0min

7030

ln)019.01( )(

0medJCK

T

30.10.2009 8

RESULTS: Dynamic fracture toughness 1

0

100

200

300

400

-200 -150 -100 -50 0 50 100 150 200

Temperature (oC)

K JC

(MPa

.m1/

2 )

Initial Initial Irradiated (2.31 dpa) Irradiated (2.31 dpa)

Weld metalT100= -13,3oC (initial)T100= +48,3 oC (2.31 dpa)

Micro TPB specimens (3x4mm) –

no side grooves

Roell

Amsler

RKP 50 impact tester (nominal capacity of 50 J,

max.testing energy 6,29 J)

Impact velocity : 1,36

m/s

0

100

200

300

400

-200 -150 -100 -50 0 50 100 150 200

Temperature (oC)

K JC (

MPa

.m1/

2 )

Initial initial Irradiated (2.43 dpa) Irradiated (2.43 dpa)

BM Eurofer 97T100= -41,5oC (initial)T100= +71,5 oC (2.43 dpa)

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RESULTS: Dynamic fracture toughness 2

0

100

200

300

400

-200 -150 -100 -50 0 50 100 150 200Temperature (oC)

K JC

(1T)

(MPa

.m1/

2 )KJC(1T)MASTER CURVEKJC(0,05)KJC(0,95)KJC(1T)-invalid valuesKJC(1T)-invalid values

EUROFER 97Weld metal - unirradiatedTo = +2,0 oCSum ni = 0,39

WELD METAL - the obtained reference temperatures To are not in compliance with the requirements of ASTM E 1921-05.

To+/-50oC

KJC limit (M=30)

30.10.2009 10

RESULTS: Static

fracture toughness 1

0

100

200

300

400

-200 -150 -100 -50 0 50 100 150 200

Temperature (oC)

K JC

(MPa

.m1/

2 )

Initial Initial Irradiated (2.31 dpa) Irradiated (2.31 dpa)

Weld metalT100= -118,1oC (initial)T100= -34,6 oC (2.31 dpa)

Micro TPB specimens (3x4mm) –

20% side grooved

Instron

1342,

load cell capacity 50 kN

Load point displacement has been measured using LVDT gauges

0

100

200

300

400

500

-200 -150 -100 -50 0 50 100 150 200

Temperature (oC)

K JC (

MPa

.m1/

2 )

Initial initial Irradiated (2.43 dpa) Irradiated (2.43 dpa)

BM Eurofer 97T100= -126,6oC (initial)T100= -16,7 oC (2.43 dpa)

30.10.2009 11

RESULTS: Static fracture toughness 2

0

100

200

300

400

-200 -150 -100 -50 0 50 100 150 200Temperature (oC)

K JC

(1T)

(MPa

.m1/

2 )KJC(1T)MASTER CURVEKJC(0,05)KJC(0,95)KJC(1T)-invalid valuesKJC(1T)-invalid values

EUROFER 97Base metal - irradiatedTo = +6,1oCSum ni = 0,52

All the obtained reference temperatures To are not in compliance with the requirements of ASTM E 1921-05.

To+/-50oC

KJC limit (M=30)

30.10.2009 12

RESULTS: Static

fracture toughness 3

J-R test in upper shelf have been performed in accord with ASTM E 1820-

01.

Because of small dimension of Micro-TPB samples, ASTM as well

as

ESIS/CSN qualification of the JQ

validity was not been satisfied.

From comparison of J-R curves it

is seen that JQ

values were reduced by approx. 50 % for BM and 30% for WM.

Low sensitivity of weld metal to neutron irradiation embrittlement

in

comparison of Eurofer

97 base metal.

Eurofer97 Base material, T=+24 oC

0

100

200

300

400

500

600

700

0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70

Crack growth (mm)

J-in

tegr

al (k

J.m

-2)

B220-unirradiated

B220-unirradiated

B221-unirradiated

B221-unirradiated

A45-unirradiated

A45-unirradiated

A46-unirradiated

A46-unirradiated

B310-irradiated

B310-irradiated

B311-irradiated

B311-irradiated

B312-irradiated

B312-irradiated

Eurofer97 Weld metal, T=+24 oC

0

100

200

300

400

500

600

700

0,00 0,10 0,20 0,30 0,40 0,50 0,60 0,70

Crack growth (mm)

J-in

tegr

al (k

J.m

-2)

U1-210unirradiatedU1-210unirradiatedU1-310unirradiatedU1-310unirradiatedU1-117unirradiatedU1-117unirradiatedU1-28 irradiated

U1-28 irradiated

U1-29 irradiated

U1-29 irradiated

U1-31 irradiated

U1-31 irradiated

30.10.2009 13

SUMMARYTransition temperature shifts

*… Invalid value of To (ASTM E1921-05). Maximum KJC capacity (M=30) has not been fulfilled + results outside To+/-50 oC.

Low sensitivity of weld metal to neutron irradiation embrittlementin comparison of Eurofer 97 base metal.

Specimen set

Displ. per atom(dpa)

Dynamic fracturetoughness

Static fracturetoughness

ΔT100

(oC)ΔT0

(oC)ΔT100

(oC)ΔT0

(oC)

BM 2.43 113.0 122.6 109.9 101,6*

WM 2.31 61.6 74.7* 83.5 99.0*

113.0

61.6

109.9

83.5

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SUMMARY Effect of specimen size and geometry on To

Static fracture toughness results

Eurofer

97 BM

To

determined according to ASTM E1921-05

Transition temperature To

appears to be in-dependent on specimen size and geometry.

Good agreement of NRI INVALID To

values in comparison with the other data [1,2]

-150

-100

-50

0

50

100

150

200

0 2 4 6 8 10

Dose (dpa)

T o (o C

)

CT B=5mm (NRG) CT B=10mm (NRG)TPB B=10mm (SCK) TPB B=3mm (NRI)

Data from:[1]Final report for EFDA project Task2[2]E. Gaganidze: Assessmemt of Fracture Mechanical and Impact Experiments of Irradiated Eurofer97 and RAFM Steels. Barcelona, 2007.

DoseAATo exp121

A1 =-107.4 oC, A2 =297.8 oC,τ=4.23 dpa [2]

30.10.2009 15

SUMMARY Shift in transition temperature To

Static and dynamic fracture toughness results Eurofer

97 BM

To

determined according to ASTM E1921-05

Good agreement of NRI INVALID To

values in comparison with the other data [1,2]

Dynamic fracture toughness shift do not differ significantly in comparison with static fracture temperature shifts

0

50

100

150

200

250

300

0 2 4 6 8 10Dose (dpa)

Shift

To

(o C)

100mm bar (SCK) 8+14mm plate (NRG)25mm plate (NRG) SFT To 14mm plate (NRI)SFT T100 14mm plate (NRI) DFT To 14mm plate (NRI)DFT T100 14mm plate (NRI)

Data from:[1]Final report for EFDA project Task2[2]E. Gaganidze: Assessmemt of Fracture Mechanical and Impact Experiments of Irradiated Eurofer97 and RAFM Steels. Barcelona, 2007.

DoseATo exp1

A1 =268.9 oC, τ=3.58 dpa [2]

30.10.2009 16

CONCLUSIONS

Low sensitivity of weld metal to neutron irradiation embrittlement

in comparison of Eurofer

97 base metal.

Transition temperature To

appears to be in-dependent on specimen size and geometry.

Dynamic fracture toughness shift do not differ significantly in comparison with static fracture temperature shifts.

Additional testing : It will be performed impact testing on un-irradiated and irradiated sub-sized Charpy-V specimens (3x4 mm).

30.10.2009 17

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