r&d of ferritic-martensitic steel ep450 ods for fuel pin ...d of ferritic-martensitic steel...
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R&D of ferritic-martensitic steel
EP450 ODS for fuel pin claddings
of prospective fast reactors
Joint Stock Company "High-technological Institute of Inorganic Materials"
(JSC VNIINM), Moscow, Russia
IAEA Technical meeting on “Design, Manufacturing and Irradiation Behaviour
of Fast Reactors Fuels”, 10 May-03 June 2011, IPPE
V.S. Ageev, A.A. Nikitina, A.P. Chukanov,
N.P. Porezanov, V.V. Tsvelev, O.A. Kruglov
Exploitation conditions for fuel pin
cladding materials of fast reactors
Large difference in temperatures along fuel pin cladding (370-700 °С)
High fluence of neutrons (~2 × 10²³ n/сm² @ Е>0,1 МeV)
Influence of stresses from gaseous debris of fuel fission and from mechanical interaction with swelling fuel rod.
Aggressive corrosion environment (coolant on outside surface of fuel pin cladding and products of fuel fission: Cs, Te, I and other – on inner surface of cladding)
Besides, material for fuel cladding must be corrosion resistant during long-term water storage of worked-out test assemblies in cooling pond
Technological scheme of receiving of
ODS steels
Receiving of matrix steel powder with
spherical or scaly shape of particles by the
centrifugal atomization of melt from revolving
crucible in inert gas (He) atmosphere.
Mechanical alloying of received powder by
particles of Y2O3 in vibration high-energy mill.
Vibro-infill of steel cans by received
powder blend, decontamination and sealing
of cans.
Hot pressing of steel cans with powder on
hydraulic press with tonnage 600 tons at
1100 °C into compact billets with maximum
possible density.
Hot extrusion at 1150 °С of compact billets
in hot-extruded bars with drawing no more
than 10-12 and subsequent mechanical
treatment
Structure and chemical composition of steel EP450
a – optical microscopy
b – transmission electron microscopy
Element content, wt. %
С Si Mn Cr Ni Mo Nb V B P
0,10-
0,15
<0,5 <1,0 11,0-
13,5
0,05-
0,30
1,5-
2,0
0,15-
0,40
0,1-
0,3
0,005-
0,015
<
0,025
a b b a b
Powder of matrix steel EP450
b a a b
a – external view;
b – microstructure of powder received by TEM
Powders of yttrium oxide
External view of yttrium oxide powder of industrial production (SEM) and microstructure of separate agglomerate (TEM) of yttrium oxide crystallites
Yttrium oxide powder, received with application of special technology: external view (TEM) and histogram of distribution of particles by sizes
Microstructure of powder of steel EP450 mechanically alloyed by
0,3 wt.% of Y2O3 and 0,4 wt.% of TiH
а b а b
c
а, b – structure in initial state;
c – structure after annealing at 1150 ºС
during 30 min
Hot extrusion
Bars
Tube shells
Microstructure of a bar from steel EP450 ODS, received with use of yttrium oxide
powder of industrial production (a-c) and histogram of distribution of oxide
particles by sizes in it (d)
а а b b
c
d
а а b b
c c
d
Microstructure of a bar from steel EP450 ODS, received with use of yttrium oxide
received by special technology (a-c) and histogram of distribution
of oxide particles by sizes in it (d)
а b
а а
а b b
c d
Microstructure of steel EP450 ODS (SEM) (a) and images of microstructure
in characteristic X-ray emissions of titanium and yttrium
Material Test
temperature, оС
Stress, MPа Creep rate,
%/h
EP450 650 140 1,18*10-2
EP450 ODS 650 140 2,38*10-4
EP450 700 120 9,1
EP450 ODS 700 120 1,82*10-3
Thermal creep curves of plate samples from steels EP450 and EP450 ODS
@ temperatures 650 and 700°С
Microstructure of hot rolled plate
from steel EP450 ODS
Temperature dependence of impact toughness of specimens of steels
EP450 and EP450 ODS
Specimens for impact toughness tests :
L = 55 mm
В = 2±0,05 mm
H = 8 mm
Н1 = 6±0,1 mm
Mechanical properties of plates 0,4 mm from EP450 ODS steel with different
initial deformation ratio
def. ratio, % elongation, % YS , MPа UTS, MPа
20 7,1 839 885
30 6,6 868 909
40 6,2 881 922
50 5,0 893 945
60 4,6 912 960
70 3,8 1086 1169
Specimens of thin-walled tubes
6,9х0,4х1000 mm
from steel EP450 ODS
Structure (a – optical microscopy; b, c – TEM) of thin-walled tube from steel EP450 ODS
after finish heat treatment 1150 ºС, 1,5 h, then 740 ºС, 2h and histogram of distribution
of oxide particles, which present in structure of tubes (d)
0
5
10
15
20
25
30
35
40
Vo
lum
e f
racti
on
,%
1-3 4-6 7-10 10-20 20-40 40-100
Particle size, nm
a b
c
d
c
a b b
Material Test
temperature, °С
Stress, MPа Internal
pressure,
kg/mm2
Time to rupture,
h
EP450
700
120
150
20
ChS139 85
EK181 90
EP450 ODS 200
Thermal creep curves of tube specimens of steels EP450 and EP450 ODS
at temperatures 650 и 700 °С
Data of long-term tests on tube specimens under internal pressure of steels
EP450, EP450 ODS and heat-resistant precipitation-hardening martensitic steels
Material
Test
temperature, оС
Stress,
MPа
Time to
rupture, h
Creep rate,
%/h
Comment
EP450 650 140 0 1,18*10-2 Ruptured
during loading
EP450
ODS
650 140 9086 2,38*10-4 δ=7,92%
EP450 700 120 23 9,1 δ=2,83%
EP450
ODS
700 120 1080 1,82*10-3 δ=7,08%
Thermal creep curves, received on microspecimens with 0,4×2,5×7 mm gauge
length cut from experimental tubes from steel EP450 ODS in longitudinal direction
Рис. . Кривые ползучести образцов ЭП-450-Y2O3
Т исп. = 650°С
1 - σ=140 Мпа
2 - σ=170 Мпа
3 - σ=210 МПа
0
0,5
1
1,5
2
0 2000 4000 6000 8000 10000 12000 14000 16000
t, час
Dl,
мм
2
1
3
Thermal creep curves of steel EP450ODS
(experimental batch of tubes)
at 650°С and stresses 140 (1), 170 (2)
and 210 (3) MPа
Рис. . Кривые ползучести образцов ЭП-450-Y2O3Т исп. = 700°С
1 - s=120 Мпа
2 - s=140 МПа
3 - s=160 МПа
4 - s=170 МПа
0
0,5
1
1,5
2
2,5
3
3,5
4
0 2000 4000 6000 8000 10000 12000 14000 16000
t, час
Dl,
м
м
1
3
4
2
Thermal creep curves of steel EP450ODS
(experimental batch of tubes)
at 700°С and stresses 120 (1), 140 (2)
160 (3), 170 (4) MPa
Type of specimen Тtest., °С UTS, MPa YS, MPа Elongation, %
Ring
(transverse direction)
20 740±62 677±40 3,1±0,6
Tube
(longitudinal direction)
910±10 707±6 16,6±0,9
Ring
(transverse direction)
650 407±23 390±10 3,1±1,9
Tube
(longitudinal direction)
420±17 363±21 20,1±0,8
Ring
(transverse direction)
700 297±49 280±52 4,5±0,5
Tube
(longitudinal direction)
307±12 273±15 21±2
Mechanical properties of tube specimens of steel EP450 in
longitudinal and transverse directions after finish heat treatment
а – optical microscopy;
b, c – TEM
Microstructure of thin-walled tubes from steel EP450 ODS, pilot batch
of which was received in JSC «Machine Building Plant» (MSZ)
c
а b b
melting
zone
steel EP450 ODS
Microstructure of welded joint between cladding tube and plug from steel
EP450 ODS received with use of argon arc welding (optical microscopy)
changes structural state of ODS steel
tube
plug
Microstructure of welded joint between plug and cladding tube from steel
EP450 ODS, received by pressurized resistance welding (optical microscopy)
Equipment for pressurized resistance welding
External view of technological specimen from steel
EP450 ODS received by pressurized
resistance welding
welded
joint
scanning
line
joint of cladding tube and plug from steel
EP450 ODS after pressurized
resistance welding
Graphics of distribution of intensity of X-ray
characteristic emission of titanium and
yttrium in welded joint of cladding tube and
plug from steel EP450 ODS after pressurized
resistance welding
welding zone
cladding tube
Quality of welded joint received by
pressurized resistance welding
Estimated by biaxial tension under
internal pressure 120 MPa at temperature
700 ºС.
Typical kind of rupture – outside of
welding zone
Specimens which were put in material test
assembly of BN-600 in the beginning of 2010
механические свойства
physical properties
fracture toughness
mechanical properties
Irradiation conditions for specimens
in material test fuel assembly of BN-
600:
Irradiation temperature: 375-700ºC
Stage 1.
Maximum damage dose 80 d.p.a
Stage 2.
After replacement in new material
test fuel assembly
Maximum damage dose 140-160d.p.a
Flowing and static sodium
environment
Conclusion
• In the course of presented works over research and development of steel EP450 ODS the possibility of significant increase of heat resistance of ferritic-martensitic steels by dispersion strengthening them by nanoparticles of yttrium-titanium oxides was shown.
• Technological schemes of receiving powders, tube shells and thin-walled tubes from steel EP450 ODS were worked out.
• Principle possibility of hermetization of thin-walled tubes from steel EP450 ODS by method of pressurized resistance welding was shown.
2010
Road map of a project “Development of nanostructured oxide dispersion strengthened
(ODS) heat-resistant steels for elements of cores of fast reactors of new generation
(with different types of coolant) and elements of fusion reactor
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
Development of experimental technology of receiving the ODS steels
Fabrication of experimental batches of tubes from ODS steels and investigation of their properties
Development of industrial technology and receiving of industrial batches of tubes
Imitating investigations on accelerators
Reactor tests of ODS steels in material test assembly and irradiation device of reactors BOR-60 and BN-600
Postreactor investigations of irradiated cladding tubes from ODS steels
Analysis of experimental data and choice of ODS steels for fuel claddings of reactors with sodium,
lead and lead- bismuth eutectic coolants