Brazing Technologies Creating Value in IGT Component Restoration

Turbine ForumNice, France

April 23rd, 2015

Presented by:

Turbine Controls Inc.

Hemann Munasinghe, Principal Engineer, FAA-DER

Morgan Advance Materials

Alan Demmons, Product Development Engineer, Metallurgist

Luca Leone, Application Engineer, EU Aerospace and IGT MRO Market

The Turbine

Taken from www.etspowergroup.com

Solution required

• Operator of Siemens Westinghouse IGT looking to avoid replacing $800,000 of row four buckets

• Desired economical repair

Condition of the blades

• Prior Repairs

• Significant Wear

• Cracks

4th Row Buckets– Base Material Mar-M-247

Considering traditional approaches

Plasma/HVOF• Customer Specified Triballoy T800 material• We would expect to see:

• Coating brittle at thicknesses required (practical limitation of 0.070”/1.78mm)

• Excessive wear/chipping

• Shear strength limitationTaken from Watsongrinding.com

Considering traditional approaches

Welding• Customer Specified Triballoy T800 material• We would expect to see:

• Excessive Cracking

• Not a practical process

Photo taken from http://lwfluidmachine.com/

Braze repair an alternative to welding

Consider a Proven Alternative – Braze Repair

• Braze repair of Aircraft Engine Turbine Components utilized for ~20 years

• Highly regulated qualification

• Safety Critical

CFM EnginesCFM56 all models

P&W EnginesJT3DJT4AJT8DJT9DPW2000PW4000

GE EnginesCF34-3CF34-8CF34-10CF6GE90GEnx

EA EnginesGP7200

RR EnginesRB211Trent 500Trent 700Trent 800Trent 1000BR710

IAE EnginesV2500 all models

Aircraft Engine Models Employing Braze Repairs

Braze Repair with Pre-Sintered Preforms (PSP)

• Pre-Sintered Preforms (PSP)

• PSP = Superalloy Powder + Braze Alloy Powder

• Brazing and Diffusion Steps in Vacuum Furnace• Compatible with parent metal• Properties similar to parent metal

Repair of Cracks

DimensionalRestoration

1mm

PSP Metallography

Engineering Considerations for Braze

• Base Material: Mar-M-247 • Specified hard face T800• Minimum bond strength of 37.9MPa

• Required <1% porosity • Giving required toughness and wear strength

• Needed to survive coating thermal cycles • Target cost required to be economical

Wetting Sag Reflow Porosity

A Continuous Development Process

Initial Approach and Learnings

• Dimensional and crack repair with Mar-M-247 PSP• Machine• Plasma coat T800 for hard-face• Finish machine

Successful BondPorosity

Revised Approach

• Dimensional and crack repair with Mar-M-247 T800 PSP

• Machine• Plasma coat T800 for hard-face• Finish machine

Multiple Repairs, Single Process

• T800 PSP – New Composition

• Significant dimensional repair 3.18mm (0.125”)

• Desired multiple repairs in a single cycle (Cost)

• Holding geometry important to minimize grinding and shaping (Cost)

TEMP

TIME

True metallurgical bond achieved T800 PSP

T 800 Plasma Final braze result T800

Successful repair achieved with T800 PSP

• Full PSP repair in one cycle• Multiple dimensional repairs • Crack repairs with paste• 30-40 Blades per cycle

DSC guides design of braze and sinter cycles

DSC Results Final alloy – Developed short period of time

Chemical Composition and Physical Properties

Key constituents Co Ni Cr W Mo Si C B Al Ti Other

AlloyHardness,

Rc“T”

limited

Laves 29 – 35 Y X X X X

Carbide 32 – 63 Y X X X

T800 HVOF 44 – 60 Y X X X X

PSP T800 40 - 66 N X X X X X X X Ta - Hf

Mar-M- 509 Base X X X X X X X X X Ta – Hf

Mar-M-247 Base X X X X X X X X

Family of alloys that exhibit excellent resistance to wear and corrosion• Main constituents of Stellite alloys are Co, Cr, W, Mo,C• Hardness from 32 – 63 HRC

Known for their properties in high temperature applications• Excellent resistance to galling and metal-to-metal adhesive wear• Particularly in the absence of lubrication• Low coefficient of friction gives good sliding wear properties

Validating integrity of repair

T800 Plasma Vickers (Hv) Rockwell (Rc)

Average 520.4 50

High 697.2 60

Low 440.7 44

T800 PSP Vickers (Hv) Rockwell (Rc)

Average 597.5 55

High 862.1 66

Low 384.9 39

Validating Phase Structure

SEM/EDS Line scan PSP T800

Analyzing integrity of repair – element mapping

Boron

ChromeCobalt

Moly Iron

SEM SE

Validating integrity of repair

HVOF T-800 to Mar-M-247 PSP T-800 to Mar-M-247

Validating integrity of repair

• Repaired parts have been in operation over 2 years

• Next steps:• Characterize fatigue and wear performance of PSP

versus base metal• Characterize dimensional rebuild limits• Application Specific

Benefits of PSP solution for TCI

• Capable repair process, gives business offering • Able to use specified materials, delivering improved repair

using T800 • Cost Effective Repair enables profitability

• One cycle for full repair • 20 to 30 blades per cycle (weeks for welding)• No iteration to repair cracks from welding• Minimal grinding / shaping• Solution and Ageing cycle combined• No welding expertise required (Co)

• Metallurgically superior, delivers higher technical confidence

Benefits of PSP solution for IGT Operator

• Saved the parts, otherwise parts would be scrapped and replaced (c$800,000 costs)

• Costs of repair significantly lower than budget• Quicker turn around (1 week), giving less down time• Higher quality repair- superior durability compared to

other repair methods

Delivering a repair solution quickly

Material ExpertiseMetallurgy

Braze Repair Experience

PSP ManufacturingBraze Process

Expertise

Repair DevelopmentBrazing Expertise

Application ExpertiseAerospace Repair

ExperienceManufacturing

Capabilities

Morgan Advanced Materials Turbine Controls Inc.

Summary

• TCI and Morgan worked together to develop a repair procedure to recover parts that would previously have been scrapped, saving parts worth an estimated $800,000.

• The recovery method also reduced the repair steps required compared with conventional processes, reducing cost and improving productivity.

• The repair process gives a higher performing repair, that can be translated across the parts spectrum opening up repairs on other turbines.

Thank you for listening