Thermo Mechanical Fatigue Behaviour of Bare and Coated CMSX-4

2008 ◽  
Author(s):  
T. Coppola ◽  
S. Riscifuli ◽  
O. Tassa ◽  
G. Pasquero
Keyword(s):  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Behaviour ◽  
Tensile Creep ◽  
Thermal Gradients ◽  
Test Program ◽  
Mechanical Fatigue ◽  
Complete Set ◽  
Comparison Of The Results ◽  
Very High

Highly cooled turbine blades undergo very high thermal gradients during rapid engine Idle-Max-Idle cycling. Traditional isothermal fatigue data are often insufficient for predicting service lives. A complete set of high temperature tests, in the range of 750 to 1050°C, was performed on single crystal alloy CMSX-4. The test program comprised tensile, creep, low cycle fatigue (LCF) and thermo-mechanical fatigue (TMF) tests. In particular the cycle time for TMF was 3 min., aiming to simulate the real high-power transient conditions in aircraft engines. Clockwise and counter-clockwise diamond cycle types were applied on bare and coated specimens to investigate their influence on the fatigue limit. The comparison of the results obtained with the available ones from open literature is discussed.

Thermomechanical Fatigue Behavior of Bare and Coated CMSX-4

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
T. Coppola ◽  
S. Riscifuli ◽  
O. Tassa ◽  
G. Pasquero
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Thermomechanical Fatigue ◽  
Tensile Creep ◽  
Thermal Gradients ◽  
Test Program ◽  
Complete Set ◽  
Comparison Of The Results ◽  
Very High

Highly cooled turbine blades undergo very high thermal gradients during rapid engine idle-max-idle cycling. Traditional isothermal fatigue data are often insufficient for predicting service lives. A complete set of high temperature tests, in the range of 750–1050°C, was performed on single crystal alloy CMSX-4. The test program comprised tensile, creep, low cycle fatigue, and thermomechanical fatigue (TMF) tests. In particular the cycle time for TMF was 3 min, aiming to simulate the real high-power transient conditions in aircraft engines. Clockwise and counterclockwise diamond cycle types were applied on bare and coated specimens to investigate their influence on the fatigue limit. The comparison of the results obtained with the available ones from open literature is discussed.

scholarly journals Lifing the Effects of Crystallographic Orientation on the Thermo-Mechanical Fatigue Behaviour of a Single-Crystal Superalloy

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 998
Author(s):  
Richard Smith ◽  
Robert Lancaster ◽  
Jonathan Jones ◽  
Julian Mason-Flucke
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Damage Mechanism ◽  
Fatigue Behaviour ◽  
Limiting Factors ◽  
Mechanical Fatigue ◽  
Design Engineers ◽  
Service Environments ◽  
Nozzle Guide

Thermo-mechanical fatigue (TMF) is a complex damage mechanism that is considered to be one of the most dominant life limiting factors in hot-section components. Turbine blades and nozzle guide vanes are particularly susceptible to this form of material degradation, which result from the simultaneous cycling of mechanical and thermal loads. The realisation of TMF conditions in a laboratory environment is a significant challenge for design engineers and materials scientists. Effort has been made to replicate the in-service environments of single crystal (SX) materials where a lifing methodology that encompasses all of the arduous conditions and interactions present through a typical TMF cycle has been proposed. Traditional procedures for the estimation of TMF life typically adopt empirical correlative approaches with isothermal low cycle fatigue data. However, these methods are largely restricted to polycrystalline alloys, and a more innovative approach is now required for single-crystal superalloys, to accommodate the alternative crystallographic orientations in which these alloys can be solidified.

scholarly journals Microstructural aspects of fatigue in Ni-base superalloys

2015 ◽  
Vol 373 (2038) ◽  
pp. 20140128 ◽  
Author(s):  
Stephen D. Antolovich
Keyword(s):  
Life Prediction ◽  
Turbine Blades ◽  
Deformation Mode ◽  
Substitutional Solid Solution ◽  
Fatigue Behaviour ◽  
Jet Engines ◽  
Mechanical Fatigue ◽  
Nickel Base ◽  
Actual Size ◽  
Notched Components

Nickel-base superalloys are primarily used as components in jet engines and land-based turbines. While compositionally complex, they are microstructurally simple, consisting of small (50–1000 nm diameter), ordered, coherent Ni 3 (Al,Ti)-type L1 2 or Ni 3 Nb-type DO 22 precipitates (called γ ′ and γ ′′ , respectively) embedded in an FCC substitutional solid solution consisting primarily of Ni and other elements which confer desired properties depending upon the application. The grain size may vary from as small as 2 μm for powder metallurgy alloys used in discs to single crystals the actual size of the component for turbine blades. The fatigue behaviour depends upon the microstructure, deformation mode, environment and cycle time. In many cases, it can be controlled or modified through small changes in composition which may dramatically change the mechanism of damage accumulation and the fatigue life. In this paper, the fundamental microstructural, compositional, environmental and deformation mode factors which affect fatigue behaviour are critically reviewed. Connections are made across a range of studies to provide more insight. Modern approaches are pointed out in which the wealth of available microstructural, deformation and damage information is used for computerized life prediction. The paper ends with a discussion of the very important and highly practical subject of thermo-mechanical fatigue (TMF). It is shown that physics-based modelling leads to significantly improved life prediction. Suggestions are made for moving forward on the critical subject of TMF life prediction in notched components.

Thermo-Mechanical Fatigue Behaviour of the Gamma-Titanium Aluminide TNB-V5 with Near-Gamma Microstructure

2007 ◽  
Vol 539-543 ◽  
pp. 1559-1564 ◽  
Author(s):  
M. Roth ◽  
Horst Biermann
Keyword(s):  
Fatigue Life ◽  
Cyclic Deformation ◽  
Gas Turbines ◽  
Titanium Aluminides ◽  
Mechanical Load ◽  
Low Cycle Fatigue ◽  
Fatigue Behaviour ◽  
Attractive Alternative ◽  
Combustion Engines ◽  
Mechanical Fatigue

The efficiency of aircraft and industrial gas turbines and combustion engines depends on the maximum operation temperature and, therefore, on the properties of the commercial high temperature materials. In the temperature range 500°C to 750°C γ-titanium aluminides especially alloys of the third generation represent an attractive alternative to the established nickel-base superalloys which have the double density. Due to superimposed cyclic thermal and cyclic mechanical loadings during start-up and shut-down operations structural components in gas turbines and combustion engines may not only be exposed to isothermal but also to thermo-mechanical fatigue (TMF). In this study the cyclic deformation and fatigue behaviour under thermo-mechanical load of the γ-TiAl alloy TNB-V5 with near-gamma microstructure is evaluated. To set a fatigue-life relation strain-controlled thermo-mechanical fatigue tests were carried out with two different strain ranges, different temperature-strain cycles and different temperature ranges from 400°C to 800°C. Additional low-cycle fatigue (LCF) tests were performed at 400°C, 600°C and 800°C for comparison. Cyclic deformation curves, stress-strain hysteresis loops and fatigue lives of the tests are presented. The shortest fatigue lives are always observed in out-of phase (OP) tests, the longest in in-phase (IP) tests. Clockwise-diamond (CD) and counter-clockwise diamond (CCD) testing yield similar fatigue lives intermediate between those of OP and IP tests. For a general life prediction the double-logarithmic plot of the damage parameter by Smith, Watson and Topper vs. fatigue life is well suitable.

Investigation of Stress Stabilization Behavior of Type 316 Steel

2013 ◽  
Author(s):  
Mohammad R. Hormozi ◽  
Farid Biglari ◽  
Kamran M. Nikbin
Keyword(s):  
Low Cycle Fatigue ◽  
Direct Method ◽  
Kinematic Hardening ◽  
Experimental Investigations ◽  
Thermal Gradients ◽  
Element Analysis ◽  
Mechanical Fatigue ◽  
The Finite Element Analysis ◽  
A Direct Method ◽  
Strain Cycling

Some materials are designed to operate at high temperature environments with high thermal gradients and will be subject to thermal and mechanical cyclic strains. Under these cyclic temperatures and strains, thermo-mechanical fatigue (TMF) and low cycle fatigue (LCF) failure occur which will lead to the initiation of damage and cracking and subsequent crack growth. In this paper the numerical and experimental investigations of stress stabilization of 316FR steel subjected to strain cycling in the temperature range of 400–650 °C has been presented. The material exhibited both cyclic and nonlinear kinematic hardening behavior. In this paper the finite element analysis of cyclic loading of the materials was based on a direct method to use the test data from a stabilized cycle in combination with the hysteresis strain energy concept for damage derivation.

Low-Cycle Fatigue Behaviour of Gas Turbine Alloys

1974 ◽  
Vol 188 (1) ◽  
pp. 321-328 ◽  
Author(s):  
W. J. Evans ◽  
G. P. Tilly
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
High Stress ◽  
Cyclic Creep ◽  
Fatigue Curve ◽  
Fatigue Behaviour ◽  
Material Surface ◽  
Tension Stress ◽  
Cycle Fatigue ◽  
Stress Tests

The low-cycle fatigue characteristics of an 11 per cent chromium steel, two nickel alloys and two titanium alloys have been studied in the range 20° to 500°C. For repeated-tension stress tests on all the materials, there was a sharp break in the stress-endurance curve between 103 and 104 cycles. The high stress failures were attributed to cyclic creep contributing to the development of internal cavities. At lower stresses, failures occurred through the growth of fatigue cracks initiated at the material surface. The whole fatigue curve could be represented by an expression developed from linear damage assumptions. Data for different temperatures and types of stress concentration were correlated by expressing stress as a fraction of the static strength. Repeated-tensile strain cycling data were represented on a stress-endurance diagram and it was shown that they correlated with push-pull stress cycles at high stresses and repeated-tension at low stresses. In general, the compressive phase tended to accentuate cyclic creep so that ductile failures occurred at proportionally lower stresses. Changes in frequency from 1 to 100 cycle/min were shown to have no significant effect on low-cycle fatigue behaviour.

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