1 journées d ’automne 2001 structural materials for hybrid system paris, 29-31 octobre 2001 o....

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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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EM10Ti (9Cr 1Mo 0.1C 0.17Ti)

Tn = 1050°C / 20min

Tn =1250°C/20min

Tn =1250°C/20min

TiN

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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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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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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).


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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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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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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


Steel normalised at 1150°C/30min and quenched

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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).

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EM10Ti (9Cr 1Mo 0.1C 0.17Ti)

10 m

10 m

C K

10 m

N K

10 m

SE Ti K

10 m

Courtesy of CAMECA

1 journées d ’automne 2001 structural materials for hybrid system paris, 29-31 octobre 2001 o....

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