The document summarizes the development of materials for gas turbine and jet engine turbine blades. It discusses how earlier blades were made of steel but nickel-based superalloys were introduced in the 1940s as they had better high-temperature capabilities. It describes how wrought alloys were initially used but cast alloys became popular with advances in casting. It also outlines trends in processing like investment casting and directional solidification, and how cooling and coating technologies improved to allow higher firing temperatures.

1. Material Development for Gas Turbine
and Jet Engine Turbine Blades
Presented By:
Ahmed Galal
Presented To:
Dr. Hanady Salem

2. Outline
• Concept of Gas Turbine Operation
• Service conditions of turbine blades
• Blade Development
– Material Development
– Processing Development
– Cooling Trends
– Coatings

3. Concept of Gas Turbine Operation
1- Intake air compressed by compressor blades
2- Fuel injected at combustion chamber
3- Gases reach turbine blades to drive compressor and :
- Generate Power in case of gas turbine
- Generate thrust (gases) in case of jet engine
http://www.cmse.ed.ac.uk/

4. Turbine Blade Service Conditions
Turbine blades are exposed to many types of
stresses that can cause different modes of
failure:
1- Cyclic Fatigue
2- Thermal Fatigue
3- Creep
4- Hot Corrosion
5- Erosion

5. Blade Development
• Turbine development measured by firing
temperatures
• Higher firing temperature Higher
efficiency and higher power/weight ratio
• Major limiting factor on temperature is
Creep

6. Material Development
• First turbine used “stayblade” steel. Not enough creep resistance
• It was replaced by Rex 78, age hardened austenitic steel
• 1940s was the introduction of Ni based superalloys. Since that
time, all turbine blades have been made of these alloys.

8. Material Development
• First turbine used “stayblade” steel. Not enough creep resistance
• It was replaced by Rex 78, age hardened austenitic steel
• 1940s was the introduction of Ni based superalloys. Since that
time, all turbine blades have been made of these alloys.
• These alloys had the best high temperature capabilities
compared to other alloys

10. Material Development
1- Wrought Alloys:
• First Ni alloys were wrought, processed by forging
• Nimonic 75, 80 were first introduced.
• Excellent creep resistance due to precipitation
hardening of secondary phase γ’ of Ni3Al and Ni3Ti
• Increasing Cobalt by 20% Nimonic 90, 50C
• Increasing Al, Ti increase of creep resistance
• Increasing Mo increase SSS
• Nimonic 105 and 115

11. Material Development
1- Cast Alloys:
• Increase of Al and Ti decrease in solidus and liquidus temperatures,
increase in hardening phase solution temperature limit on
hot working temperature, difficult to add intricate details gave rise
to cast blades.
• Cast blades became popular with advancement in vacuum melting and
investment casting.
• First alloy was Inconel 713C, others were developed in 1960s such as
Inconel 100.
• Modern alloys contain 10 + alloying elements:
- SSS (Co, Cr, Fe, Mo, W)
- Grain boundary strengthening by carbide forming elements (W, Ti, Mo, Cr)
- Improve Corrosion and oxidation Resistance (Al, Cr, Y, La, Si, Co, Ce)
- Grain Boundary refiners (C, B, Zr, Hf)

12. Processing Development
1- Investment Casting:
• Vacuum process, reduces oxide contamination
• Produces equiaxed grain structure
• Continuous advances in process cleanliness led to improvement of blade
properties.
2- Directional Solidification:
• Controlled microstructure
• No transverse or inclined grain boundaries

13. Materials Research Laboratory – University of California, Santa Barbara

14. Materials Research Laboratory – University of California, Santa Barbara

15. Materials Research Laboratory – University of California, Santa Barbara

16. Materials Research Laboratory – University of California, Santa Barbara

17. Processing Development
3- Single Crystal:
• No grain boundaries
• Crystal Alignment

18. Materials Research Laboratory – University of California, Santa Barbara

19. Materials Research Laboratory – University of California, Santa Barbara

20. Cooling Trends
• Blade cooling enables increasing firing temperature while
maintaining blade at lower temperatures.
• First trend was convection cooling through air passes
• Then film cooling was introduced

21. Coating Trends
1- For Oxidation:
• Aluminide diffusion coating
• MCrAlY coating by Physical vapor deposition
2- Thermal Barrier Coating (TBC):
• Using ceramic materials such as Zirconia (0.3-0.4 mm thick),
deposited over a layer of MCrAlY overlay coating

22. Materials Research Laboratory – University of California, Santa Barbara

23. Boyce, Meherwan. Gas Turbine Engineering Handbook, Second Edition, GPP, 2002