ICME Design of Ni Superalloys and Optimization for ... · ICME Design of Ni Superalloys and...

CHiMaD/SRG30

Mar 23-24, 2015

QuesTek Proprietary Information

p. 1

ICME Design of Ni Superalloys and Optimization for

Additive Manufacturing

CHiMaD/SRG30

31st Annual Meeting

Jiadong Gong, PhD

Senior Materials Design Engineer

QuesTek Innovations

Mar 24, 2014

CHiMaD/SRG30

Mar 23-24, 2015


p. 2

Outline

• ICME Background

• Case Study: Single Crystal Ni

– Design and Modeling

– Prototype and Characterization

• Additive Manufacturing of Ni Alloys

• Conclusion and Future

CHiMaD/SRG30

Mar 23-24, 2015


p. 3

ICME Methodologies

(Materials by Design®)

Genotypic mechanistic-based approach

Traditional Empirical Methods

(“trial and error”)

Empirical approach

The ICME methodologies

ICME: a paradigm change from the traditional empirical methodologies methods

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Mar 23-24, 2015


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Computational Materials Design Overview

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QuesTek’s ICME based Materials by Design®

• Combines rigorous stage gate materials design process with

proprietary:

– Thermodynamic & kinetic elemental databases

– Materials-specific software

– Mechanistic models (input chemistry and processing) for prediction

CHiMaD/SRG30

Mar 23-24, 2015


p. 6

QuesTek ICME Architecture

CHiMaD/SRG30

Mar 23-24, 2015


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ICME/MGI framework for Materials by Design

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Case Study: Single Crystal Ni Superalloy for IGT

• SX castings – High Temperature Performance

– Desirable from a creep standpoint – no grain boundaries

• IGT blade castings are large > 8 inches

– Slower solidification / cooling rates exacerbate processing issues (below)

• Primary casting (processing) constraints:

– Freckle formation

– Formation of high angle boundaries (HAB) and low-angle boundaries (LAB)

– Hot-tearing

– Shrinkage porosity

• 3rd generation blade alloys are especially difficult to cast as

SX due to their high refractory content

– Increased tendency for hot tearing

– Increased tendency for freckle formation

QuesTek’s proposed approach: ICME-based design of a new processable, high-

performance single crystal alloy for IGT applications

CHiMaD/SRG30

Mar 23-24, 2015


p. 9

Systems design chart for SX castings

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Mar 23-24, 2015


p. 10

Modeling and design tasks

• Thermodynamic and kinetic database

• Freckling model

• Processing design (HT windows, incipient melting)

• γ + γ’

– Including γ’ coarsening model

• TCP, HAB and LAB

• Creep modeling (intermediate temperature)

– Calculation of “Reed-D” for existing alloys (climb-controlled creep)

– Develop explicit vacancy diffusivity model

• Oxidation/alumina formation

• Alloy design

Models used in

Phase I design

“Indirect

consideration”

during Phase I

design (for further

expansion in

potential Phase II)

Alloy design in

Phase I

CHiMaD/SRG30

Mar 23-24, 2015


p. 11

List of benchmark alloys

ID Re Al Co Cr Hf Mo Ta Ti W other

PWA1480 - 5 5 10 - - 12 1.5 4

PWA1483 - 3.6 9 12.2 - 1.9 5 4.1 3.8 0.07C

GTD444 - 4.2 7.5 9.8 0.15 1.5 4.8 3.5 6 0.08C

CMSX7 - 5.7 10 6 0.2 0.6 9 0.8 9

CMSX8 1.5 5.7 10 5.4 0.2 0.6 8 0.7 8

PWA1484 3 5.6 10 5 0.1 2 9 - 6

CMSX4 3 5.6 9 6.5 0.1 0.6 6.5 1 6

Rene N5 3 6.2 7.5 7 0.15 1.5 6.5 - 5 0.01Y

CMSX10 6 5.7 3 2 0.03 0.4 8 0.2 5 0.1Nb

TMS238 6.4 5.9 6.5 4.6 0.1 1.1 7.6 - 4 5.0Ru

QuesTek’s Phase I design (“QT-SX”) contained these same

elemental constituents, but with 1% Re

Re-free

alloys

Recently-

developed

2nd Gen alloys

High-Re alloys

CHiMaD/SRG30

Mar 23-24, 2015


p. 12

Modeling of liquid density during solidification

7.615

7.620

7.625

7.630

7.635

7.640

7.645

7.650

1,320 1,330 1,340 1,350 1,360 1,370 1,380 1,390 1,400 1,410 1,420

ReneN5 Liquid density vs. T

40%

20%

liquid

density,

g/c

m3

Temperature, °C

liquidus

Actual modeling

output is a

combined use of

various databases

and software

Freckle-resistance is related to the modeling of the liquid density during

solidification base on a critical Rayleigh number:

CHiMaD/SRG30

Mar 23-24, 2015


p. 13

0

0.005

0.01

0.015

0.02

0.025

0.03

(b): Liquid density difference at 20% solidification

0.00E+00

2.00E-20

4.00E-20

6.00E-20

8.00E-20

1.00E-19

1.20E-19

1.40E-19

(a): Coarsening Rate Constant for different alloys

Coarsen rate and liquid density difference comparisons

Comparable coarsening rate

to CMSX-8 (1.5% Re) alloy

Reduced buoyancy

differences (less than

non-Re CMSX-7)

(lower is better)

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Mar 23-24, 2015


p. 14

(left) Setup of the small scale test slab cluster

(right) Picture of actual casting with N5 showing a bi-grain formation,

Simulation of chosen casting scenario with N5: (a) R contour (b) G contour (c) location designations

One “tree” (four

castings) produced by

PCC from both N5 and

QT-SX

1st round of casting results

CHiMaD/SRG30

Mar 23-24, 2015


p. 15

As-cast microstructures

QT-SX

ReneN5

Along growth direction Transverse

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Modeling freckling behavior in N5 and QT-SX castings

Target this range (>B, <A)

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Mar 23-24, 2015


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2nd round of casting results

CHiMaD/SRG30

Mar 23-24, 2015


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2nd round of casting results

CHiMaD/SRG30

Mar 23-24, 2015


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Single Crystal Microstructure of fully heat treated alloys

Characterization and microstructure analysis confirm the achievement of the design goal of γ’ phase fraction and lattice misfit

(no evidence of TCP phases were found during all heat treatments)

after double-step aging

CHiMaD/SRG30

Mar 23-24, 2015


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Atom-probe (LEAP) analysis of the QT-SX nanostructure

Ion, at.% Cr % Ni % Co % Al % Hf % Mo % Re % Ta % Ti % W %

LEAP1 1.74 66.76 6.63 17.28 0.05 0.61 0.10 3.43 0.38 2.84

LEAP2 1.92 70.34 6.64 16.97 0.08 0.85 0.07 0.72 0.42 1.79

Prediction 2.1 69.0 6.0 16.9 0.05 0.23 <0.01 4.0 0.19 1.6

γ'

γ

γ'

γ'

γ

γ'

γ'

γ'

Excellent agreement

with predicted

compositions (γ’

comparisons below)

CHiMaD/SRG30

Mar 23-24, 2015


p. 21

Evolution of microstructures during long-term exposure at

elevated temperature

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Oxidation modeling progress

Oxygen concentration computed at

FCC/Oxide* boundary assumed to be the

content in FCC when the spinel forms

• Both Al2O3 and Cr2O3 expected to form at high T

• Internal Al2O3 expected to form below 850°C

Model agrees well with experimental data for benchmark alloys

• Continuous Al2O3 and Cr2O3 formation

• Wahl applied Wagner’s model to multicomponent systems

𝑦𝑀0 ≥ 𝑦𝑀𝐶1

0 =𝜋𝑔

2𝜈𝑁𝑜

𝐷𝑂𝑉𝐴𝑙𝑙𝑜𝑦𝐷𝑀𝑉𝑀𝑂

1/2

CHiMaD/SRG30

Mar 23-24, 2015


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Oxide characterization

EDS mapping of continuous oxide in QTSX alloy heat treated for 100h at 1000°C.

Continuous Al-rich oxide observed in all samples

QTSX oxidized in air for 100h at 900°C, 1000°C and 1100°C

CHiMaD/SRG30

Mar 23-24, 2015


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QuesTek Creep Modeling

• Gamma’ Coarsening Rate Constant

• Reed creep merit index: Assumes that the diffusivity at the γ/γ’ interface

controls the climb process = rate controlling mechanism during creep

Alloy Creep merit index (m-2 s *1015) Coarsen KMP*1020

CMSX-10 6.93 4.59

PWA1484 5.68 5.97

CMSX-4 4.51 6.00

TMS-75 4.49

QTSX 3.97 6.59

René N5 3.82 7.17

TMS238 3.47 4.94

PWA1483 2.77 12.2

Re free

1 wt.% Re

3 wt.% Re5 ≥ wt.% Re

QTSX is predicted to have creep behavior similar to alloys containing higher

amount of Re, like the 2nd generation alloys

CHiMaD/SRG30

Mar 23-24, 2015


p. 25

Oxidation-Creep merit Summary

1000°C

parameters

should be

maximized for

improved

behavior

QTSX is predicted to have creep behavior and oxidation behavior similar to

benchmark alloys, and is not necessarily sensitive to compositional variations

CHiMaD/SRG30

Mar 23-24, 2015


p. 26

Experimental creep data

Resistance to creep: Maximize Larson-Miller parameter (LMP)

– Time to rupture at given temperature and stress

QTSX is measured to have creep behavior similar to the 2nd generation

alloys, confirming the design prediction.

CHiMaD/SRG30

Mar 23-24, 2015


p. 27

Summary: Single Crystal Ni Superalloy for IGT

• A demonstration of successful computational

Materials by Design® methodologies

• A final round of full IGT-size casting will be performed

to serve as the final validation of the highly processable

design

• Further characterization and testing is on-going for

accelerated qualification and insertion

CHiMaD/SRG30

Mar 23-24, 2015


p. 28

Additive Manufacturing of Ni Superalloys

QuesTek is participating the DARPA Open Manufacturing Program on the additive

manufacturing of 718Plus Ni-Superalloy, collaborating with Honeywell Aerospace.

Acknowledge: DARPA contract number HR0011-12-C-0037.

Use or disclosure of information contained on this page is subject to the restrictions on the cover.

Yield Strength Prediction for Additive

QuesTek predicted Yield Strength based on actual production heat treat parameters and microstructure:

• Cooling rate from solution temperature

• DMLS Grain size and evoluation

DMLS IN718PLUS RT yield strengths are better than Cast IN718PLUS but significantly lower than Forged IN718PLUS

Based on initial Uncertainty Quantification findings, QuesTek calibrated YS model using APB energy and following the probabilistic methodology developed under the DARPA AIM program.

StressRelief

HIP

Solution

Age

Acknowledge: DARPA contract number HR0011-12-C-0037.

CHiMaD/SRG30

Mar 23-24, 2015


p. 30

Additive Manufacturing of Ni Superalloys

Solid Solution Ni-base Superalloy: The microstructure and

property modeling for the additive processing of a Ni-Cr-W-Mo

alloy that combines excellent high-temperature strength and

oxidation resistance with superior long term stability and good

fabricability.

High fraction Ni-base Superalloy: The composition and

process optimization of a Ni-base superalloy commonly used

for blade rings and high pressure turbine blades. It is

traditionally a polycrystalline cast alloy with exceptional high

temperature strength (high precipitate fraction), corrosion and

oxidation resistance.

Other Additive Fronts at QuesTek:

CHiMaD/SRG30

Mar 23-24, 2015


p. 31

Conclusions and Future Directions

• Thermodynamic and process modeling tools have been developed/applied

to the design of highly processable high creep strength Ni-base single

crystal superalloys

• CALPHAD calculations and PrecipiCalc® simulations optimized the

design and the heat treatment process

• The predictions are in good agreement with the experimental observations

of the microstructures and the compositions validated via SEM and LEAP

• Prototypes has been produced and the testing results show excellent

properties and high potential for market success

• The ICME tools and databases are also playing a critical role in the

composition and process optimization of the additive manufacturing

process of Ni-base alloys

• Future research and development will help accelerate scale-up,

manufacturing optimization, qualification and insertion of the materials

CHiMaD/SRG30

Mar 23-24, 2015


p. 32

Thank you!

Questions?

You are welcome to contact us for licensing, producing,

application inquiries or further development cooperation!

CHiMaD/SRG30

Mar 23-24, 2015


p. 33

Back up

CHiMaD/SRG30

Mar 23-24, 2015


p. 34

Oxidation merit calculations using Ni7 database

“Oxidation merit index”:

combine ΔG and Valeff into one

parameter, for easy ranking of alloys

distance from point to line

Oxidation prone

Oxidation resistant

Alloy Oxidation merit index

PWA1484 0.176

CMSX-7 0.157

TMS-138A 0.120

QTSX 0.117

CMSX-8 0.092

René N5 0.079

TMS-75 0.075

CMSX-4 0.067

PWA1483 -0.031

CMSX-10 -0.059

TMS238 -0.092

1000°C

Re free

1 wt.% Re

3 wt.% Re5 ≥ wt.% Re

ICME Design of Ni Superalloys and Optimization for ... · ICME Design of Ni Superalloys and...

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