Heat resistance properties of HP super-alloy are represented via phase transformation of their micro-structure.

1. Heat resistant austenitic
stainless steels
Master research project
Student : Andrey GRISHIN
Tutor: Anna FRACZKIEWICZ
Karolina MAMINSKA
Andrey GRISHIN - Master Research Student

2. Production of hydrogen
Natural Gas
≈ 90 % Reforming
Nuclear High-
Temperature Gasification
Electrolysis
Photobiological
Renewable
and
Liquid
Photoelectroche-
Reforming
mical
Andrey GRISHIN - Master Research Student 2

3. Natural Gas Reforming
http://www.hydrocarbonprocessing.com/
Article/2598005.html
Andrey GRISHIN - Master Research Student 3

4. Creep of reformer tubes
Laser-Optic Tube
Inspection Method Stages of creep Creep damage
T>0,5 Tm
σ=const
Creep
Dislocation creep
Modes of creep:
http://www.ndt.net/article/v10n03/roberts/roberts.htm Diffusion creep
Andrey GRISHIN - Master Research Student 4

5. Dislocation creep
Power-law breakdown: glide contributes
increasingly to the overall strain-rate
D b 3
 2
 kT
http://engineering.dartmouth.edu/defmech/c
hapter_2.htm
Andrey GRISHIN - Master Research Student 5

6. Diffusion creep
Diffusional flow by diffusional transport
through and round the grains. The strain-
rate may be limited by the rate of diffusion
or by that of an interface reaction.
 D
 NH  2
d kT
http://engineering.dartmouth.edu/defmech/c  D j 
hapter_2.htm  Co 
d 3 kT 6
Andrey GRISHIN - Master Research Student

7. Heat resistant alloys of HP type
Austenite Precipitation
stabilization of
Ni 33-37 fine
Nb ~ 0,6-0,8 carbides
Corrosion Cr 24-28
resistance Ti ~ 0,05 intragranulary
C 0.35-0.75
V ~ 0,05
Precipitation Fe - bal HP alloy
of carbides and
solid solution Chem.comp.
Strengthening %
effect
Mo ~ 0,05
Si ~ 1
Mn ~ 0,8
Al ~ 0,01
W ~ 0,05
Andrey GRISHIN - Master Research Student 7

8. Centrifugal casting technique
The
rotation
speed from
250 to 3600
RPM
Resistant
to
atmosphe-
ric
corrosion Any length,
thickness
and
diameter
Cooling-down is very fast
http://www.centrifugalcasting.com/technical.htm
Andrey GRISHIN - Master Research Student 8

9. Solidification
1- Liquid
2-Austenite
3- NbC
4- Cr7C3
5- Cr23C6
Andrey GRISHIN - Master Research Student 9

10. As-cast material
Dendritic
structure
Primary
Big size of grains
carbides (NbC,
(mm) Microstructure evolution of HP40-Nb alloys during aging under
air at 1000 °C
Raluca Voicua, Eric Andrieua, Dominique Poquillona, Jader Furtadob, Jacques Lacazea,⁎
Cr7C3, Cr23C6)
Andrey GRISHIN - Master Research Student 10

11. In-service state
C (Phase) wt
100%
90
80
Liquid
70
Austenite
60 NbC
50 M7C3
40 M23C6
6
30
20 5
10 4
0 T, C 3
600 700 800 900 1000 1100 1200 1300 1400 1500
2
1
0
1200 1220 1240 1260 1280 1300 1320
Andrey GRISHIN - Master Research Student 11

12. In-service state
Aging:
850 C, 48h
Andrey GRISHIN - Master Research Student 12

13. In-service state
1
2
3
EDX
analysis
Andrey GRISHIN - Master Research Student 13

14. Conclusion
The microstructure of the as-cast alloy is
austenitic with the primary Cr- and Nb-carbides
In the in-service state the microstructure of alloy
is changed: the secondary precipitation occurs in
the matrix
In order to impose the mechanical properties
such as creep resistance we need to obtain the
fine secondary precipitates dispersed in the
matrix
Andrey GRISHIN - Master Research Student 14

15. What next?
The study of
microstructure • Qualitative and
transformation of
one of the HP alloy quantitative analysis.
modifications.
Qualitative and
• Technics:
quantitative SEM, TEM, EDX...
analysis using
Andrey GRISHIN - Master Research Student 15

16. Thank you for your attention!
Andrey GRISHIN - Master Research Student 16