Liburdi Engineering Limited

• Liburdi Engineering Ltd• Liburdi Turbine Services Inc• Liburdi Automation Inc• Liburdi Dimetrics Corp

• Dundas, Ontario• Davidson, North Carolina• St Petersburg, Russia

Liburdi Group of Companies

Dundas, Ontario Canada

Davidson, NC, USA

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Turbomachinery

Conference Houston, TX September 13-17, 2009

PowerGen

Conference Las Vegas, NV December 7-10, 2009

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Superalloys

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Typical Gas Turbine Component Materials

Turbine Stationary300SS, 400SSN-155, M509, HS-188,L605X-40, X-45, FSX-414, ECY-768IN738, R80, GTD222, GTD444

Turbine Rotating

Waspalloy, U-500, U520, U700, U710, U720, INX750, IN738, Rene80, GTD111, M247, M002,PWA1483, CMSX4, ReneN5

Piping, tubing, valves, etc.Steel

Compressor CasingsGrey Cast IronCarbon Steel

Turbine ShellsDuctile Cast Iron

Compressor Wheels/DisksNi-Cr-MO-VForging

Turbine Wheels/DiscsNi-Cr-MO-V Steel Cr-Mo-V Forging12Cr StainlessDiscalloyA286IN718

CompressorSome 300SS403, 410, 422, 450 StainlessIN718Ti64 titanium

Combustor300SSHastelloy-X, RA-33 L-605IN-600, IN-617Nimonic 75, Nimonic 263Haynes 230

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SUPERALLOYS

1. Definition and Properties2. Strengthening Mechanisms

- Solid Solution Hardening- Precipitation Hardening and Heat Treatment- Grain Boundary Hardening and Control

3. Surface Stability: Oxidation and Hot Corrosion

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SUPERALLOY DEFINITION

•Superalloys have remarkable mechanical strength at high temperatures -- up to 80% of their incipient melting point.

•Superalloys exhibit the highest surface stability in air at elevated temperatures of engineering alloys.

•Superalloys are also “exotic” as they can contain up to 12 elements – And they can have as many elements specifically excluded.

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ALLOY PROPERTIES

Metals and their alloys have varying strength andoxidation resistance (and cost)

Alloys used for Turbine Blades/Buckets

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MECHANICAL PROPERTIES

Fe/Ni-based superalloys are economical, high strength forging alloys for low and intermediate temperaturesNi-based superalloys can withstand high creep stresses at intermediate and high temperaturesCo-based superalloy are castable, weldable, and useful at very high temperature and corrosive environments

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Compositions and Properties - Nickel Based Alloys

•Sheet alloys like Hasteloy X have low Aluminum + Titanium content have excellent formability

•Forged alloys like Udimet 520, Nimonic105, X750 have a moderate Aluminum + Titanium content, have good mechanical properties but are forgeable. Used for intermediate-temperature buckets.

•Cast alloys like CMSX, GTD111, IN738, MM247 have a high Aluminum + Titanium content, have excellent mechanical properties at elevated temperature and are used for the highest temperature blades.

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SUPERALLOY PROPERTIES

Excellent mechanical properties in the service temperature and stress range that gas turbine blades operate in, even after prolonged service

•Excellent creep strength

•Useful mechanical strength

•Good fatigue and thermal fatigue properties

•Adequate ductility and toughness (low crack growth rates)

•Useful thermal expansion characteristics

•Excellent resistance to oxidation and corrosion

•Alloy additions form self-healing protective scales

•Fabricability (forging, casting, welding, machining, coating)

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SUPERALLOY DESIGN

•Solvent can be cobalt, iron or nickel (usually a mixture of nickel and cobalt)

•Oxidation protection provided by aluminum & chromium

•Solutes, molybdenum, niobium, rhenium, tantalum, tungsten

•Precipitation formers: aluminum, titanium, niobium

•Grain strengtheners: carbon, hafnium, zirconium, boron

•Tramp elements: silver, boron, silicon

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Cast Nickel Based Alloy Compositions

Alloy Ni Cr Co Mo W Ta Cb Al Ti Fe Mn Hf C B Zr Others

Ni-Base Alloys

Alloy 713C 74 12.5 0.0 4.2 0.0 0.0 2.0 6.1 0.8 0.0 0.0 0.0 0.12 0.012 0.10

B-1900 64 8.0 10.0 6.0 0.0 4.0 0.0 6.0 1.0 0.0 0.0 0.0 0.10 0.015 0.10

C-1023 58 15.5 10.0 8.5 0.0 0.0 0.0 4.2 3.6 0.0 0.0 0.0 0.16 0.006 0.00

CMSX- 2 66 8.0 4.6 0.6 7.9 5.8 0.0 5.6 0.9 0.0 0.0 0.0 0.00 0.000 0.00

GTD-111 60 14.0 9.5 1.5 3.8 2.8 0.0 3.0 4.9 0.0 0.0 0.0 0.10 0.01 0.03

GTD-222 51 22.5 19.0 0.0 2.0 1.0 0.8 1.2 2.3 0..0 0.0 0.0 0.10 0.010 0.01

IN-100 60 10.0 15.0 3.0 0.0 0.0 0.0 5.5 4.7 0.0 0.0 0.0 0.18 0.014 0.06 1.0 V

IN-738LC 61 16.0 8.5 1.7 2.6 1.7 0.9 3.4 3.4 0.0 0.0 0.0 0.11 0.010 0.05

IN-939 48 22.5 19.9 0.0 2.0 1.4 1.0 1.9 3.7 0.0 0.0 0.0 0.15 0.009 0.09

IN-792 61 12.4 9.0 1.9 3.8 3.9 0.0 3.1 4.5 0.0 0.0 0.0 0.12 0.020 0.10

MarM-002 61 9.0 10.0 0.0 10 2.5 0.0 5.5 1.5 0.0 0.0 1.5 0.14 0.015 0.05

MarM-247 60 8.3 10.0 0.7 10 3.0 0.0 5.5 1.0 0.0 0.0 1.5 0.10 0.015 0.05

PWA-1483 61 12.8 9.0 1.9 3.8 4.0 0.0 3.6 4.0 0.0 0.0 0.0 0.07 0.0 0.0

Rene-N5 62 7.0 8.0 2.0 5.0 7.0 0.0 6.2 0.0 0.0 0.0 0.2 0.0 0.0 0.0 3.0 Re

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PRECIPITATION STRENGTHENING

Superalloys are strengthened by carbide and gamma-prime (γ׳) precipitatesSubstitution of aluminium for nickel in γ lattice results in γ phase of the ׳composition Ni3Al.Titanium and niobium can substitute for aluminium in γ ׳The volume fraction of γ’ phase formed is a function of the hardener content

Increasingcreep

strength

Increasing γ ׳volume

γ phase in Ni-based superalloy ׳

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Gamma Prime (γ´) Strengthening (cont.)

Cuboidal primary γ´ phase

Spherical secondary γ´ phase

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PRECIPITATION STRENGTHENING

For a given volume of γ׳ in nickel superalloy, maximum strength is developed at anoptimum precipitate sizeHeat treatments are used to create the optimum precipitate size(s).In reality, it is both the size and spacing between γ׳precipitates that is responsible for strength.

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ALLOY HEAT TREATMENT

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GRAIN BOUNDARY HARDENING: BY CARBIDES

MC carbides form at high temperature and precipitate throughout the matrix with little influence on strengthM23C6 or M6C particles form preferentially along grain boundaries during aging cycles and service exposureThe particles inhibit grain boundary sliding and add to strength – however there is an optimum carbon addition level (0.1-0.2%) beyond which properties degrade

Grain boundary carbide particles in IN939 alloy

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GRAIN SIZE STRENGTHENING

Fine grain sizes provide high tensile and fatigue strengths, BUT lower creep strengths result

Fatigue of IN718, IN901 and Waspaloy

Creep of IN738

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GRAIN ORIENTATION – ADVANCED CASTING TECHNOLOGIES

Equiaxed

Directionally Single Cry

stal (SC)(polycrystalline] Solidified (DS) [monocrystalline]

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GRAIN ORIENTATION

Grain boundaries are the “weakest-link” in polycrystalline superalloy behaviour. If the stresses are highly uniaxial, and the service temperature is very high, significant improvements can be made through controlling grain-boundary orientation or eliminating them altogether during casting.

equiaxed columnar single crystalPolycrystal DS Directional SX

Solidification

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TRENDS IN TURBINE BLADE ALLOYS and GRAIN ORIENTATION

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COMPARATIVE DS, SX AND POLYCRYSTAL PROPERTIES

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SURFACE STABILITY: OXIDATION AND HOT CORROSIONEngineering alloys are not “stainless”, they all form oxide scales in air.Scale formation rate is a function of temperature and environmentSome native scales are not protective (Fe, Mg)Some native scales are protective (Al, Cr, Ti)Alloying enough “protective” element into “non-protective” can impart protection (ie: 12+% chromium into iron makes “stainless steel”)Protective elements can be added to base alloy or clad over as a “coating”

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NATIVE OXIDE SCALES HIERARCHY FOR SUPERALLOYS AND COATINGS

Al2O3 Very ProtectiveNiAl2O4

NiTa2O6

CrTaO4

Cr2O3 ProtectiveNiCr2 O4

CoCr2O4

NiTiO3

NiO Not helpfulCoOTiO2

W, Mo, refractory oxides

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Advanced Design Turbine Blades (Industrial Frame Engines Now Using Aero Cooling, Aero Alloys)

Manufacturer/Model First Stage Turbine Blade / Bucket

Alstom-GT24/26Single Crystal, Ni-BaseMatrix CooledVPS-NiCoCrAlY with APS-TBC

GE-Frame 7“FA”Directionally Solidified, GTD111Serpentine Cooling w/TurbulatorsLPPS-CoCrAlY/DVC-TBC, Plus Internal Coatings

Siemens V84.3ASingle Crystal PWA1480VPS-CoNiCrAlYSi

Plus Internal Coatings

Siemens- Westinghouse 501G

Directionally Solidified CM247Serpentine, Film & Showerhead VPS-NiCoCrAlY/TBC

GE LM2500+RR RB211 GT

Single Crystal N5 (GE), CMX4 (RR)Serpentine, Film & Showerhead PT Al Coating plus internal Coating (LM2500+)