Long-term Creep-Fatigue Interactions in Ni-base Superalloys Plastic Deformation Plastic Deformation

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Transcript of Long-term Creep-Fatigue Interactions in Ni-base Superalloys Plastic Deformation Plastic Deformation

  • Long-term Creep-Fatigue Interactions in Ni-base Superalloys

    Award DE-FE0011722 August 2013 – August 2016

    Program Manager: Briggs White

    PI: Richard W. Neu GRAs: Ernesto A. Estrada Rodas, Sanam Gorgan Nejad and Anirudh Bhat

    The George W. Woodruff School of Mechanical Engineering School of Materials Science & Engineering

    Georgia Institute of Technology Atlanta, GA 30332-0405 rick.neu@gatech.edu

    University Turbine Systems Research Workshop Georgia Institute of Technology

    November 3-5, 2015

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Hot Section Gas Turbine Materials

    Land-based gas turbines  drive to increase service

    temperature to improve efficiency; increase life

     replace large directionally- solidified Ni-base superalloys with single crystal superalloys

    Power Output: 375 MW

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Single Crystal Alloy being Investigated for IGT Applications

    CMSX-8: 1.5% Re "alternative 2nd gen alloy" replacing 3.0% Re containing alloys (e.g., CMSX-4, PWA1484)

    [Wahl and Harris, 2012]

    Strength

    Creep

    Alloy

    Cr

    Co

    Mo

    W

    Al

    Ti

    Ta

    Re

    Hf

    C

    B

    Zr

    Ni

    Mar-M247LC-DS

    8.4

    10.0

    0.7

    10.0

    5.5

    1.0

    3.0

    -

    1.5

    0.07

    0.015

    0.05

    Bal

    CM247LC-DS

    8.1

    9.2

    0.5

    9.5

    5.6

    0.7

    3.2

    -

    1.4

    0.07

    0.015

    0.01

    Bal

    CMSX-4

    6.5

    9.0

    0.6

    6.0

    5.6

    1.0

    6.5

    3.0

    0.1

    -

    -

    -

    Bal

    SC16

    16

    0.17

    3.0

    0.16

    3.5

    3.5

    3.5

    -

    -

    -

    -

    -

    Bal

    PWA1484

    5.0

    10.0

    2.0

    6.0

    5.6

    -

    9.0

    3.0

    0.1

    -

    -

    -

    Bal

    CMSX-8

    5.4

    10.0

    0.6

    8.0

    5.7

    0.7

    8.0

    1.5

    0.2

    -

    -

    -

    Bal

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Thermomechanical Fatigue (TMF)

    Linear In-Phase (IP) Linear Out-of-Phase (OP)

    Time, t

    St ra

    in , ε

    (% )

    Thermal Strain Mechanical Strain Total Strain

    Cold

    Tension

    Compression

    Hot

    Time, t

    St ra

    in , ε

    (% )

    Thermal Strain Mechanical Strain Total Strain

    Cold

    Tension

    Compression

    Hot

    Hardening Process

    Plastic Deformation

    Plastic Deformation

    Creep

    Oxidation

    Cyclic Ageing and Coarsening effects

    Hardening Process

    Plastic Deformation

    Cyclic Ageing and Coarsening effects

    Plastic Deformation

    Creep

    Oxidation

    Φ=0° Φ=180°

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Effect of Tmin on OP TMF of CMSX-4

    [Arrell et al., 2004]

    3x

    2x drop

    [Kirka, 2014]

    CMSX-4 [001]

    CM247LC DS in Longitudinal Dir.

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Life Modeling Approach

    Damage Mechanism Modules

    Fatigue

    Creep-Fatigue

    Environment- Fatigue

    Creep Ratchetting

    Dominant Damage

    Deformation Response

    Lo ad

    in g

    Pa ra

    m et

    er

    Life

    Accurrate representations of the deformation response highly critical for predicting crack formation

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Primary Objectives of UTSR Project

    • Creep-fatigue interaction experiments on CMSX-8

    • Influence of aging on microstructure and creep-fatigue interactions

    • Microstructure-sensitive, temperature- dependent crystal viscoplasticity to capture the creep and cyclic deformation response

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Creep-Fatigue Interaction Studies

    • Conventional creep-fatigue (baseline)  ASTM E2714-09

    • Long-term creep followed by fatigue • Fatigue followed by long-term creep • Impact of pre-aging • Creep-fatigue interaction life analysis • Orientations: , , • Application to TMF with long dwells

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Conventional Creep-Fatigue (baseline)

    In a creep-fatigue interaction test, life can be controlled by:

    • Plastic strain range • Environmental effects • Influence of mean stress / stress range • Creep damage (dwell) • Microstructure / crystal orientation

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Conventional Creep-Fatigue (baseline)

    0.30

    0.50

    0.70

    0.90

    1.10

    1.30

    1.50

    100 1000 10000

    St ra

    in ra

    ng e

    [% ]

    Cycles to Failure

    Effect of hold on LCF life: R = -∞

    (T = 950 [°C], R = -1) (T = 1100 [°C], R=-1) (T = 950 [°C], R = -∞, hold = 3 min.) (T = 1025 [°C], R = -∞, hold = 3 min.) (T = 1100 [°C], R = -∞, hold = 3 min.)

    1100 [ºC]

    950 [ºC]

    950 [ºC]

    1000 [ºC]1025 [ºC]

    0.30

    0.50

    0.70

    0.90

    1.10

    1.30

    1.50

    100 1000 10000

    St ra

    in ra

    ng e

    [% ]

    Cycles to Failure

    Effect of hold on LCF life: R = 0

    (T = 950 [°C], R = -1) (T = 1100 [°C], R = -1) (T = 950 [°C], R = 0, hold = 3 min.) (T = 1025 [°C], R = 0, hold = 3 min.) (T = 1100 [°C], R = 0, hold = 3 min.)

    950 [ºC]

    950 [ºC]

    1000 [ºC]

    1025 [ºC]

    1100 [ºC]

    t

    ε R = 0

    t

    ε R = -∞

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Conventional Creep-Fatigue (baseline)

    t

    ε R = 0

    t

    ε R = -∞

    0.3

    0.5

    0.7

    0.9

    1.1

    1.3

    1.5

    100 1000 10000

    St ra

    in ra

    ng e

    [% ]

    Cycles to Failure

    Life for low cycle creep-fatigue

    (T = 950 [°C], R = 0, hold = 3 min.) (T = 950 [°C], R = -∞, hold = 3 min.) (T = 1025 [°C], R = 0, hold = 3 min.) (T = 1025 [°C], R = -∞, hold = 3 min.) (T = 1100 [°C], R = 0, hold = 3 min.) (T = 1100 [°C], R = -∞, hold = 3 min.)

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Cycle Evolution

    150

    200

    250

    300

    350

    400

    450

    500

    0 0.5 1 1.5 2 2.5 3

    St re

    ss [M

    Pa ]

    Hold [min.]

    Cycle 1 Cycle 2

    Cycle 3 Cycle 4

    Stress relaxation

    1st 10 cycles

    Stress evolution

    T = 1100 ºC, R = 0, ∆ε = 1.0 %

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Crack Characteristics

    R = 0, T = 1100ºC, ∆ε = 0.8% Nf = 1420

    R = -∞, T = 1100ºC, ∆ε = 0.8% Nf = 980

    t

    ε R = 0

    t

    ε R = -∞

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Half-life at 1025 ºC

    ∆ε = 1.0 [%]

    ∆ε = 0.8 [%]

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Half-life at 1100 ºC

    ∆ε = 1.0 [%]

    ∆ε = 0.8 [%]

    Plastic strain range alone does not

    explain life data at high temperatures. A Coffin-Manson

    relations would not be sufficient

  • The George W. Woodruff School of Mechanical Engineering School of Materials Science and Engineering

    Primary Objectives of UTSR Project

    • Creep-fatigue interaction experiments on CMSX-8

    • Influence of aging on microstructure and creep-fatigue interactions

    • Microstructure-sensitive, temperature- dependent crystal viscoplasticity to ca