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Journées d ’Automne 2001 Structural Materials for Hybrid SystemParis, 29-31 octobre 2001O. Danylova1, Y. de Carlan2 , D. Hamon2, J-C. Brachet2, J. Henry2, A. Alamo2
1Centre de recherche d’Imphy2CEA Saclay, Service de Recherches Métallurgiques Appliquées, 91 191 Gif-Sur-
Yvette CEDEX.
Effects of spallation products Ti, P and S on
the physical metallurgy of 9Cr martensitic steels
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Preliminary calculations of quantities of spallation products created in the window (J. Henry, C. Volant, R. Legrain)
1
10
100
1000
10000
100000
H He Li Be B C N O F Ne NaMg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe
Spallation products created after one operation cycle
Co
ncen
trati
on
(ap
pm
)
Elements
Embrittlement of the material ?- Segregation at interfaces ?
- Formation of sulphides and phosphides ?
Formation of hydrides, sulphides...?
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Experimental heats to study the effects of Ti, P, S on the metallurgical and mechanical properties
Aim of the study : To obtain 9Cr martensitic steels by conventional elaboration with (Ti, S, P) in solid solution to determine mechanical and cleavage properties
Cr Mo Mn C Ti P SEM10R 9 1 0.5 0.1 0.01 0.01 0.001
EM10Ti 9 1 0.5 0.1 0.17 0.013 <0.03
EM10LMnS 9 1 <0.02 0.1 0.01 0.01 0.04
EM10TiPS 9 1 0.5 0.1 0.2 0.03 0.04
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Phase stability fields in Fe 9Cr 1Mo 0.1C martensitic steels
Calculations at the thermodynamic equilibriumSoftware MTdata with data bases : Plus and Sub_sgte
0.01
0.10
1.00
10.00
100.00
1000.00
0 200 400 600 800 1000 1200 1400 1600 1800
Temperature (°C)
Ma
ss
fra
cti
on
(%
).
AusteniteFerrite
Laves phase
M23C6
Hcp_a3
Liquid
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Cr Mo Mn C Ti P SEM10R 9 1 0.5 0.1 0.01 0.01 0.001
EM10Ti 9 1 0.5 0.1 0.17 0.013 <0.03
EM10LMnS 9 1 <0.02 0.1 0.01 0.01 0.04
EM10TiPS 9 1 0.5 0.1 0.2 0.03 0.04
EM10Ti (9Cr 1Mo 0.1C 0.17Ti)
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EM10Ti (9Cr 1Mo 0.1C 0.17Ti)
0.01
0.10
1.00
10.00
100.00
1000.00
0 200 400 600 800 1000 1200 1400 1600 1800
Temperature (°C).
Ma
ss
fra
cti
on
(%
).
AusteniteFerrite
Laves phase
M23C6
TiNTiC
Liquid
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TiN
TiN
Ti(N,C)
Ti(N,C)
Ti(Mo)C
TiN
TiC
ferrite
a) b)
Globular particlesTi(Mo)C
EM10Ti (9Cr 1Mo 0.1C 0.17Ti)
Steel normalised at 1200 °C/30min and quenched
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0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 100 200 300 400 500 600
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
W%(Si) W%(Ti) W%(Mo) W%(Cr)
D en µm
W%(Cr)W%(Si,Ti,Mo)
EM10Ti (9Cr 1Mo 0.1C 0.17Ti)
Concentration profiles (obtained with a micro probe analyser) of Cr, Mo, Si and Ti within the matrix of the steel normalised at 1150°C/ 30 min.
Ti is in solid solution.
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EM10 LMnS (9Cr 1Mo 0.1C LMn 0.04S)
Cr Mo Mn C Ti P SEM10R 9 1 0.5 0.1 0.01 0.01 0.001
EM10Ti 9 1 0.5 0.1 0.17 0.013 <0.03
EM10LMnS 9 1 <0.02 0.1 0.01 0.01 0.04
EM10TiPS 9 1 0.5 0.1 0.2 0.03 0.04
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EM10 LMnS (9Cr 1Mo 0.1C LMn 0.04S)
0.01
0.1
1
10
100
1000
0 200 400 600 800 1000 1200 1400 1600 1800
Temperature (°C)
Ma
ss
frac
tio
n (
%).
AusteniteFerrite
M23C6
Laves phase
Cr1.17S
MnS
Hcp_a3
Liquid
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EM10 LMnS (9Cr 1Mo 0.1C LMn 0.04S)
Tn = 1150°C / 20min Tn = 1350°C / 20min
The proportions of austenite and ferrite as a function of temperature are close to those observed in the EM10 standard steel.
A strong modification of the repartition of chromium sulphides is observed as a function of heat treatment
(at 1350°C, probably dissolution and reprecipitation of chromium sulphides).
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0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
0.7
0.75
0.8
0 50 100 150 200
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
W%(Mo) W%(S ) W%(Cr) W%(S)W%(Mo)
D en µm
Concentration profiles (micro probe analyser) of S and Mo within the matrix of the steel (normalised at 1300°C and quench at 100 °C/s).
EM10 LMnS (9Cr 1Mo 0.1C LMn 0.04S)
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EM10 LMnS (9Cr 1Mo 0.1C LMn 0.04S)
0,2 µm
1
5
4
3
2
100 nm
TEM examinations show small chromium sulphides (chemical composition close to 50% Cr and 50% S with a
small amount of Fe) => solubility of S is very low (close to 10 ppm at 1100 °C, according literature)
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EM10TiPS (9Cr 1Mo 0.1C 0.2Ti 0.03P 0.04S)
Cr Mo Mn C Ti P SEM10R 9 1 0.5 0.1 0.01 0.01 0.001
EM10Ti 9 1 0.5 0.1 0.17 0.013 <0.03
EM10LMnS 9 1 <0.02 0.1 0.01 0.01 0.04
EM10TiPS 9 1 0.5 0.1 0.2 0.03 0.04
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EM10TiPS (9Cr 1Mo 0.1C 0.2Ti 0.03P 0.04S)
0.01
0.1
1
10
100
1000
0 200 400 600 800 1000 1200 1400 1600 1800
Temperature (°C)
Ma
ss
frac
tio
n (
%).
AusteniteFerrite
Laves phase
M23C6
TiN
TiCMnS
Cr2P
Liquid
Calculations with the software Thermocalc
predict also the formation of Ti4C2S2
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EM10TiPS (9Cr 1Mo 0.1C 0.2Ti 0.03P 0.04S)
Ferritic Zones
Alignments of TixSy
Ti(N,C)Steel normalised at 1150°C/30min
and quenched
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Ti(NC)
Ti, Al, S
TixSy
Ti(NC)
Ti, Al, S
TixSy
TixSy
Ti, Al, S
EM10TiPS (9Cr 1Mo 0.1C 0.2Ti 0.03P 0.04S)
Steel normalised at 1150°C/30min and quenched
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EM10TiPS (9Cr 1Mo 0.1C 0.2Ti 0.03P 0.04S)
Steel normalised at 1150°C/30min and quenched Phosphorus is probably in solid solution
Si K P K
Mo L Cr K
X Ray maps obtained with a micro probe
40 µm
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Conclusions
1) Better knowledge of the effects of Ti, S and P on the physical metallurgy of Fe 9Cr martensitic steels.
2) Assessment of heat treatments to obtain doping elements in solid solution in the different steels :- alloys doped with only Ti : after heat treatment, 1000 ppm can be retained in solid solution
- alloys doped with sulphuralloys doped with sulphur : sulphides are very stable MnS, CrS, Ti(C,S) and it appears difficult to put it in solid solution even in a low manganese heat => very strong tendency of sulphur to precipitate.
- alloy doped with phosphorus : possibility to have P in solid solution
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Alloys doped with titanium in solid solution :
- possibility to perform mechanical tests and hydrogen loading to study the interactions between Ti and H.
Alloy doped with phosphorus in solid solution (EM10 TiPS) :
- possibility to study the evolution of microstructure after thermal ageing or step cooling
- the steel contains many inclusions that limit the possibility to assess the influence of P on mechanical properties
Alloys with sulphur :
- check if sulphur segregation is detectable in the EM10LMnS steel after homogenisation at high temperature and step cooling.
-Other specific experiments, like diffusion couple at 500 or 600°C, between FeS and a matrix Fe-9Cr (Ti, P) may be proposed.
For all the alloys : study of the stability under irradiation of phases with doping elements.
Perspectives
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0
2
4
6
8
10
12
-160 -120 -80 -40 0 40 80 120 160 200 240 280 320
Temperature (°C)
KV
(Jo
ule
s).
EM10 R (N : 1150°C-30 min + quench)
EM10 LMnS (N : 1150°C-30 min + quench)
EM10 Ti (N : 1150°C-30 min + quench)
EM10 TiPS (N : 1150°C-30 min + quench)
EM10LCTi(ferritic)
Impact properties(Sub-size specimens 3x4x27 mm)
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EM10MnS (9Cr 1Mo 0.1C 0.5Mn 0.04S)
0.01
0.1
1
10
100
1000
0 200 400 600 800 1000 1200 1400 1600 1800
Temperature (°C)
Ma
ss
frac
tio
n (
%).
AusteniteFerrite
Laves phase
M23C6
MnS
Liquid
HCP_A3
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1 / 2 h o u r - 1 1 0 0 ° C
t e m p e r i n g2 h o u r s - 6 3 0 ° C
w a t e r q u e n c h e d
s t e p - c o o l i n g
6 0 0 ° C1 h 5 4 0 ° C
1 5 h 5 2 5 ° C2 4 h 5 0 0 ° C
4 8 h 4 7 0 ° C7 2 h
a i r c o o l e d
d i l a t o m e t r i c m e a s u r e m e n t s
r a n g e o f c o o l i n g r a t e s
3
2 , 2
= =1 6
2,2
5
d e t a i l 6 0 °
R = 0 , 1
S c h e m a t ic v ie w o f a « s t e p - c o o l in g » t h e r m a l t r e a t m e n tp e r f o r m e d o n a lo w a l lo y e d s t e e l c o n t a in in g 1 7 0 p p m P ( f r o m
S . R a o u l , C E A /S R M A , J N M 2 5 7 ( 1 9 9 8 ) 1 9 9 - 2 0 5 )
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Fully intergranular failure mode of the martensitic structure. Quasi-cleavage failure mode of the bainitic structure
Charpy Impact test performed at -50°C on low alloyed steel with~170ppm P after cooling at different rates + tempering (630°C) +
step-cooling (from S. Raoul, CEA/SRMA, JNM 257 (1998) 199-205).