Evaluating Single Crystal
Ni-base Superalloys
- UTSR Summer Report 2012
Phillip Draa
Siemens Energy
Products – Gas Turbines
Copyright © Siemens 2012
Background
• Ni- base superalloys are used in
the hot section of gas turbines.
• Single crystal superalloys have
been used in the aerospace
industry for many years.
• Recently, the metallurgical
demands of industrial gas
turbines (IGT) have increased
and the use of single crystals is
being considered.
• IGT components are much
larger than their aerospace
counterparts and require
different metallurgical concerns.
Red: Ni-base Superalloys
Thomas-Sourmail
Orange: Steels
Blue: Ti-alloys
Copyright © Siemens AG 2012
Page 2
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Alloy Evaluation
Mechanical Properties
Physical Properties
Castability
Material Selection
Machinability
Microstructure
Oxidation Properties
Cost
Copyright © Siemens AG 2012
Page 3
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Alloy Background
Rolls-Royce, The Jet Engine, 4th edn.
•
Three alloys were chosen for study as use in the first row of a new engine design:
CMSX-486, PWA1484 and CMSX-8 (B/C)
•
CMSX-486 is the most economically priced of the three and does not require a
solution heat treatment.
•
PWA1484 is a 2nd generation alloy with good mechanical and oxidation properties.
•
CMSX-8 (B/C) is a low-Rhenium alloy that has similar properties to CMSX-4.
Copyright © Siemens AG 2012
Page 4
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Mechanical and Physical Properties
• Mechanical testing was
completed for many
different properties.
• The data was statistically
analyzed and design
curves were generated.
• Estimated properties for
alloys that have not been
tested yet were generated
using literature data.
Example of literature data
Copyright © Siemens AG 2012
Page 5
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Heat Treatment
What can we do to advantageously and
economically change the microstructure
of our as-cast components?
PWA1484
CMSX-486
CMSX-8 B/C
Copyright © Siemens AG 2012
Page 6
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Incipient Melting
Incipient melting should be avoided.
Porosity can be an indication of
melting.
PWA1484 showing a mix of casting porosity and
incipient melting.
CMSX-486
Copyright © Siemens AG 2012
Page 7
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Incipient Melting/Porosity Percentages
Alloy
Temperature, C
Average %Vf of
Incipient
Melting/Porosity
CMSX- 486
CMSX- 486
CMSX- 486
CMSX- 486
CMSX- 486
CMSX- 486
PWA1484
PWA1484
PWA1484
PWA1484
PWA1484
CMSX-8 (B/C)
As-Cast
1230
1240
1250
1260
1270
As-Cast
1300
1310
1320
1330
As-Cast
0.01
0.21
0.46
0.69
1.00
2.22
0.06
0.24
0.26
0.29
0.33
0.05
Copyright © Siemens AG 2012
Page 8
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Gamma Prime Solutioning
Take the microstructure from:
PWA1484
To this:
*Avoiding creation of incipient melting porosity.
Copyright © Siemens AG 2012
Page 9
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Gamma Prime and Porosity Analysis Technique
For PWA1484 using the PAXIT software.
Able to measure the remaining eutectic
phase, as well as undissolved gamma
prime.
Avg % Undissolved γ' Total Avg % Unsolutioned
Sample ID
Avg % Eutectic
153987
2.32
1.97
4.29
153988
1.57
0.91
2.48
153989
1.02
1.67
2.69
153990
0.29
0.23
0.52
153991
2.65
2.16
4.81
153992
1.44
0.90
2.34
153993
1.38
0.60
1.98
153994
0.88
0.49
1.37
Similar measurements can be made for the low contrast porosity.
Page 10
Aug 2012
GT EN
Copyright © Siemens AG 2012
Siemens Energy Sector F PR GT EN
Conclusions/Future Work
•
CMSX-486 was rejected for its inability to solution and any possible
rejuvenation.
•
Component designers are able to start work using curves for the new alloys.
•
Continue decreasing the total heat treatment time.
•
Validate design curves with continued testing.
•
Test other properties
Copyright © Siemens AG 2012
Page 11
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Site Visit
Lakeland
Copyright © Siemens AG 2012
Page 12
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Manufacturing Plant Visit
Gray Construction – http://www.gray.com/sites/default/files/projects/siemans_gas_turbine_040.jpg
Industrial Gas Turbine part manufacture and assembly site
Copyright © Siemens AG 2012
Page 13
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Acknowledgments
Special Thanks to:
Allister James, Cynthia Klein, Ray Snider and Sachin Shinde
Siemens Employees in Orlando and Charlotte
SWRI and the UTSR Fellowship Committee
Copyright © Siemens AG 2012
Page 14
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN
Questions?
Thank You!
Copyright © Siemens AG 2012
Page 15
Aug 2012
GT EN
Siemens Energy Sector F PR GT EN