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.

Fatigue Behaviors of a NiCrAlYSi Coated Directionally Solidified Nickel Base Superalloy

2008 ◽  
Vol 33-37 ◽  
pp. 229-236
Author(s):  
Hui Chen Yu ◽  
Bin Zhong ◽  
Xue Ren Wu ◽  
Hui Ji Shi
Keyword(s):  
Surface Roughness ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Testing Machine ◽  
Strain Range ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
Nickel Base ◽  
Base Superalloy

The fatigue behaviors of a directionally solidified (DS) nickel base superalloy, coated with a MCrAlY coating (NiCrAlYSi) were studied. Two kinds of tests were performed. One kind of tests are low cycle fatigue (LCF) test under strain control at different temperatures, another kind of tests are stress controlled LCF test with SEM-servo hydraulic testing machine for in situ cracking observation. The results show that the effect of coating on LCF life of coating/substrate system was rather different according to different strain levels and temperatures. The coating has no or less effect on LCF life under high strain range and the LCF life is governed by fatigue behavior of substrate in spite of the difference of temperature. 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. This means the failure of coating/substrate system is dominated by the cracking of surface coating under low strain range. The brittleness at 500°C lower than DBTT results in rapid stage II crack propagation. The crack initiation from coating surface was in situ observed at room temperature and 700 °C and it was found that cracks usually initiated from the surface roughness of coating and then propagate to failure. The brittleness and surface roughness are the basic acceptable causes leading to the early damage of a coating/substrate system.

scholarly journals Effect of Salt Coatings on Low Cycle Fatigue Behavior of Nickel -base Superalloy GTM-SU-718

2013 ◽  
Vol 55 ◽  
pp. 830-834 ◽  
Author(s):  
G.S. Mahobia ◽  
R.G. Sudhakar ◽  
Ajesh Antony ◽  
K. Chattopadhyay ◽  
N.C. Santhi Srinivas ◽  
...  
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Nickel Base ◽  
Base Superalloy

scholarly journals Low cycle fatigue behavior and life evaluation of a P/M nickel base superalloy under different dwell conditions

2010 ◽  
Vol 2 (1) ◽  
pp. 2103-2110 ◽  
Author(s):  
Huichen Yu ◽  
Ying Li ◽  
Xinyue Huang ◽  
Xueren Wu ◽  
Duoqi Shi ◽  
...  
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Life Evaluation ◽  
Nickel Base ◽  
Base Superalloy

Development of a Generalized LCF-TMF Lifing Model for a Nickel-Base Superalloy

2012 ◽  
Author(s):  
Björn Buchholz ◽  
Uwe Gampe ◽  
Tilmann Beck
Keyword(s):  
Power Generation ◽  
Life Prediction ◽  
Power Plants ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy

The growing share of power generation from volatile sources such as wind and photovoltaics requires fossil fuel fired power generation units be available and capable of high load flexibility to adjust to the changing capacity of the electrical grid. Additionally, back-up units with quick start capability and energy storage technologies are needed to fill the power shortfall when volatile sources are not available. Gas turbine and combined-cycle gas and steam turbine power plants are able to meet these demands. However, safe component design for improved cycling capability, combined with optimum utilization of material regarding its mechanical properties, requires design procedures and lifing models for the complex loadings resulting from this increased volatility of power demand. Since hot gas path components like turbine blades and vanes are highly stressed by cyclic thermal and mechanical loadings, resulting Thermo-Mechanical Fatigue (TMF), life prediction models such as the classic strain-life Coffin-Manson-Basquin method do not capture the influences of thermal cycling satisfyingly. Advanced TMF prediction models are thus necessary to accurately predict the durability of hot section components. This paper addresses life prediction of the Nickel-base superalloy René 80 at elevated temperature for various loading conditions. For this purpose, isothermal Low Cycle Fatigue (LCF) and corresponding TMF tests, with various temperature ranges and thermal-mechanical phase shifts, have been performed. On this basis, a systematic approach has been developed which allows assessing the key influences on TMF life. Moreover, a generalized model for fatigue has been derived, which has the potential to predict TMF life on the basis of LCF data. The knowledge gained from the model development allows an improved life prediction and better utilization of the material capabilities. Additionally, the required number of material tests for a general insight in the materials behaviour can be reduced significantly.

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