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.

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.

scholarly journals Effect of LCF Pre-Damage on Very High Cycle Fatigue Behavior of TC21 Titanium Alloy

2017 ◽  
Author(s):  
Nie Baohua ◽  
Zhao Zihua ◽  
Ouyang Yongzhong ◽  
Chen Dongchu ◽  
Chen Hong ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Mechanism Analysis ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

The effect of low cycle fatigue (LCF) pre-damage on the subsequent very high cycle fatigue (VHCF) behavior is investigated in TC21 titanium alloy. LCF pre-damage is applied under 1.8% strain amplitude up to various fractions of the expected life and subsequent VHCF properties are determined using ultrasonic fatigue tests. Results show that 5% of LCF pre-damage insignificantly affects the VHCF limit due to the absent of pre-crack, but decreases the subsequent fatigue crack initiation life estimated by Pairs’ law. Pre-cracks introduced by 10% and 20% of LCF pre-damage significantly reduce the subsequent VHCF limits. The crack initiation site shifts from subsurface-induced fracture for undamaged and 5% of LCF pre-damage specimens to surface pre-crack for 10% and 20% of LCF pre-damage specimens in very high cycle region. The fracture mechanism analysis indicate that LCF pre-crack will re-start to propagate under subsequently low stress amplitude when stress intensity factor of pre-crack is larger than its threshold. Furthermore, the predicted fatigue limits based on EI Haddad model for the LCF pre-damage specimens well agree with the experimental results.

Extrapolation Techniques for Very Low Cycle Fatigue Behavior of a Ni-base Superalloy

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Brian R. Daubenspeck ◽  
Ali P. Gordon
Keyword(s):  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Full Range ◽  
Turbine Blades ◽  
High Stress ◽  
Cycle Fatigue ◽  
Data Set ◽  
Amplitude Data ◽  
Base Superalloy

A combination of extrapolation and estimation techniques from both prior and current studies has been explored with the goal of developing a method to accurately characterize high-stress amplitude low cycle fatigue of a material commonly used in gas turbine blades with the absence of such data. This paper describes innovative methods used to predict high-temperature fatigue of IN738LC, a dual-phase Ni-base superalloy. Three sets of experimental data at different temperatures are used to evaluate and examine the validity of extrapolation methods such as anchor points and hysteresis energy trends. High-stress amplitude data points approaching the ultimate strength of the material were added to pre-existing base data with limited plastic strain to achieve a full-range data set that could be used to test the legitimacy of the different prediction methods. Each method is evaluated at a number of temperatures.

scholarly journals Effect of Low Cycle Fatigue Predamage on Very High Cycle Fatigue Behavior of TC21 Titanium Alloy

Materials ◽  
2017 ◽  
Vol 10 (12) ◽  
pp. 1384 ◽  
Author(s):  
Baohua Nie ◽  
Zihua Zhao ◽  
Yongzhong Ouyang ◽  
Dongchu Chen ◽  
Hong Chen ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Very High

Low Cycle Fatigue Behavior of Ni-Base Superalloy IN738LC at Elevated Temperature

2011 ◽  
Vol 275 ◽  
pp. 59-62
Author(s):  
Jae Hoon Kim ◽  
Kwon Tae Hwang ◽  
Keun Bong Yoo ◽  
Han Sang Lee
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Superior Performance ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Total Strain Energy

High strength nickel-base super alloys have been used in turbine blades for many years because of their superior performance at high temperature. The prediction of fatigue life for superalloys is important for improving the efficiency. In this study, low cycle fatigue tests are performed the variables of total strain range, and room and elevated temperature. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of IN738LC super alloy. The fatigue life is evaluated by the Coffin-Manson equation, also the predicted lives by plastic and total strain energy density are compared with experimental results.

Dynamic fatigue reliability analysis of turbine blades under combined high and low cycle loadings

2021 ◽  
pp. 105678952098685
Author(s):  
Peng Yue ◽  
Juan Ma ◽  
Changhu Zhou ◽  
Jean W Zu ◽  
Baoquan Shi
Keyword(s):  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Prediction Method ◽  
Damage Mechanism ◽  
Operational Reliability ◽  
Reliability Model ◽  
Fatigue Reliability ◽  
Dynamic Reliability

Establishment of damage accumulation models for reflecting the combined damage mechanism on the fatigue behavior of aero-engine turbine blades is crucial for their safety. In this work, a novel combined high and low cycle fatigue (CCF) life prediction methodology is presented as a basis of that to consider the interaction between low and high cycle fatigues. Accordingly, a dynamic reliability model is proposed to study the operational reliability of turbine blades under CCF loadings. Moreover, experimental data of materials along with the collected field data from the actual turbine blades are applied to validate the CCF life prediction model and the dynamic reliability model. The validation of the results is conducted by a comparison analysis, which indicates that the proposed life prediction method yields better accuracy, while the dynamic reliability model is proved to be more in line with the outcomes derived by the Monte Carlo simulation.

Isothermal LCF Behaviors of a NiCrAlYSi Coated Columnar-Grained Directionally Solidified Nickel Base Superalloy

2007 ◽  
Vol 353-358 ◽  
pp. 203-206
Author(s):  
Hui Chen Yu ◽  
Bin Zhong ◽  
Xue Ren Wu
Keyword(s):  
Physical Vapor Deposition ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Strain Range ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
Different Temperatures ◽  
Nickel Base ◽  
Base Superalloy

The isothermal low cycle fatigue (LCF) behaviors of a directionally solidified (DS) nickel base superalloy, coated with a NiCrAlYSi coating were studied. The study concerned NiCrAlYSi coating formed by an arc-discharged physical vapor deposition (PVD) process for protection against high-temperature corrosion and oxidation of gas turbine blades. The effect of protective coating on LCF life of coating/substrate system was investigated at high temperatures and compared with uncoated alloy. The test results show that coating has no or less effect on LCF life under high strain range and the LCF life is governed by the fatigue behavior of substrate at different temperatures. However, when strain range is smaller, crack initiation and propagation are observably affected by temperature, which leads to a shorter LCF life of coating/substrate system at 500°C and a longer LCF life at 760°C or 980°C.

The Analysis on the Low Cycle Fatigue Behavior of a Directionally Solidified Superalloy with Recrystallized Surface Layers

2008 ◽  
Vol 44-46 ◽  
pp. 43-50 ◽  
Author(s):  
Hui Ji Shi ◽  
Xian Feng Ma ◽  
Da Wei Jia ◽  
Hai Feng Zhang ◽  
Li Sha Niu
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Directionally Solidified ◽  
Surface Layers ◽  
Time Observation

Specimens of a directionally solidified superalloy with different shot peening pressure were annealed at 1220oC in vacuum condition to get recrystallized surface layers with different micro-structures. Low cycle fatigue tests of these specimens were performed at room temperature and 400oC by using an electrohydraulic load frame in the SEM system for real-time observation. The initiation and propagation of cracks were inspected and the influence of the micro-structure of the recrystallized layer on the material fatigue behavior was analyzed. The low cycle fatigue life of the specimens depends mainly on the characteristics of the recrystallized layer. When the shot peening pressure is lower, the recrystallized layer is thin and not integrated, and the fatigue life decreases obviously in comparison with that of the specimen without recrystallized surface layer. When the shot peening pressure increases, the recrystal grains are more integrated, and the fatigue life rises. A comparison of the recrystallized layers between the blade surface and the specimen surface has been done and it points that the incompact surface recrystal layer is very dangerous to gas turbine blades.

Thermomechanical Fatigue Behavior of the Ferritic Stainless Steel

2005 ◽  
Vol 297-300 ◽  
pp. 1146-1151 ◽  
Author(s):  
Keum Oh Lee ◽  
Seong Gu Hong ◽  
Sam Son Yoon ◽  
Soon Bok Lee
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Thermomechanical Fatigue ◽  
Propagation Model ◽  
Plastic Strain Range ◽  
Proposed Model ◽  
Life Prediction Model

A thermomechanical fatigue (TMF) life prediction model for ferritic stainless steel, used in exhaust manifold of automobile, was developed based on Tomkins’ two-dimensional crack propagation model. Low-cycle fatigue (LCF) and TMF tests were carried out in a wide temperature range from 200 to 650°C. New concept of plastic strain range on TMF was proposed. Effective stress concept was introduced to get a reasonable stress range in TMF hysteresis loop. The proposed model predicted TMF life within 2X scatter band. The experimental results reveal that TMF life is about 10% of isothermal fatigue life.

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