Investigation on Stress and Strain of Ni-Based Single Crystal Super-Alloy Specimen with Single Hole Based on Abacus

2021 ◽  
Vol 891 ◽  
pp. 17-22
Author(s):  
Xiang Zhen Xue ◽  
Zhi Xun Wen ◽  
Wen Xian Li
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
High Reliability ◽  
Turbine Blades ◽  
High Strength ◽  
Initial Crack ◽  
Alloy Specimen ◽  
Single Hole ◽  
Stress Ratios ◽  
Super Alloy

The Miss stress, Max.principal strain and Magnitude displacement have important influence on the fatigue life of the Ni-based single crystal super-alloy turbine blades. This work investigated The Miss stress, Max.principal strain and Magnitude displacement of Ni-based single crystal super-alloy specimen with single hole along dangerous path under different working conditions by Abacus. The results show that the initial crack length and loading stresses are larger, the crack growth on the specimen is faster, and then, the fatigue life is the shorter. Moreover, for the different stress ratios, smaller stress ratio can lead to lower fatigue life. The result is significant to design turbine of Ni-based single crystal super-alloy of high accuracy, high reliability and high strength.

Fatigue Life of Ni-Based Single Crystal Super-Alloy Specimen with Single Hole

2021 ◽  
Vol 891 ◽  
pp. 10-16
Author(s):  
Xiang Zhen Xue ◽  
Zhi Xun Wen ◽  
Wen Xian Li
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Stress Ratio ◽  
Test Results ◽  
Alloy Specimen ◽  
Paris Law ◽  
Single Hole ◽  
Alloy Material ◽  
Life Model ◽  
Super Alloy

A method of predicting the fatigue life under multiaxis loads based on the Paris law and EIFS was proposed. And the fatigue life under different loading stress and stress ratio were investigated. The results show that when the loading stress increased from 450~800 MPa, the fatigue life decreased from 6762379 to 10056, as well as when the stress ratio increased from 0.1~1, the fatigue life increased from 6762379 to 14932368. It was validated by test eventually. And the fatigue life model presented here agrees well with test results. It is significant to the prediction of turbine of Ni-based single crystal super-alloy material with filming hole.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2001 ◽  
Author(s):  
Nagaraj K. Arakere
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
High Temperature ◽  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Turbine Blades ◽  
The Core ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4 and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the Space Shuttle Main Engine (SSME) fuel turbopump are discussed. During testing many turbine blades experienced Stage II non-crystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β = 45+/- 15 degrees tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined Low Cycle Fatigue (LCF) properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75 F – 1800 F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for LCF data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the LCF data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature LCF data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with LCF test data. These curve fits can be used for assessing blade fatigue life.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2004 ◽  
Vol 126 (3) ◽  
pp. 590-603 ◽  
Author(s):  
N. K. Arakere
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Fatigue Data ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high-performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4, and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the space shuttle main engine fuel turbopump are discussed. During testing many turbine blades experienced stage II noncrystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β=45+/−15 deg tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined low cycle fatigue properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75°F–1800°F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for low cycle fatigue data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the low cycle fatigue data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature low cycle fatigue data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with low cycle fatigue test data. These curve fits can be used for assessing blade fatigue life.

scholarly journals Development of a High-Efficiency Z-Form Selector for Single Crystal Blades and Corresponding Grain Selection Mechanism

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 780 ◽  
Author(s):  
Xintao Zhu ◽  
Fu Wang ◽  
Dexin Ma ◽  
Andreas Bührig-Polaczek
Keyword(s):  
Single Crystal ◽  
High Efficiency ◽  
Geometrical Structure ◽  
Turbine Blades ◽  
Grain Structure ◽  
Two Dimensional ◽  
Coating Properties ◽  
Turbine Engine ◽  
Research Material ◽  
Super Alloy

Single crystal (SX) is widely used in modern turbine blades to improve the creep fracture, fatigue, oxidation, and coating properties of the turbine, so that the turbine engine has excellent performance and durability. In this paper, the single crystal super alloy MM247LC is used as the research material. The evolution of grain structure in a two-dimensional grain selector was studied by directional experiments, and the mechanism of grain selection in the two-dimensional channel during directional solidification was clarified. In order to optimize the production process of single crystal turbine blades, the effects of the geometrical structure of a Z-type separator (i.e., wire diameter and take-off angle) on the crystal orientation, microstructure, and grain efficiency of blades were discussed.

Subsurface Stress Fields in Face-Centered-Cubic Single-Crystal Anisotropic Contacts

2005 ◽  
Vol 128 (4) ◽  
pp. 879-888 ◽  
Author(s):  
Nagaraj K. Arakere ◽  
Erik Knudsen ◽  
Gregory R. Swanson ◽  
Gregory Duke ◽  
Gilda Ham-Battista
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Single Crystal ◽  
Turbine Blades ◽  
Stress Fields ◽  
Shear Stresses ◽  
Face Centered Cubic ◽  
Subsurface Stress

Single-crystal superalloy turbine blades used in high-pressure turbomachinery are subject to conditions of high temperature, triaxial steady and alternating stresses, fretting stresses in the blade attachment and damper contact locations, and exposure to high-pressure hydrogen. The blades are also subjected to extreme variations in temperature during start-up and shutdown transients. The most prevalent high-cycle fatigue (HCF) failure modes observed in these blades during operation include crystallographic crack initiation/propagation on octahedral planes and noncrystallographic initiation with crystallographic growth. Numerous cases of crack initiation and crack propagation at the blade leading edge tip, blade attachment regions, and damper contact locations have been documented. Understanding crack initiation/propagation under mixed-mode loading conditions is critical for establishing a systematic procedure for evaluating HCF life of single-crystal turbine blades. This paper presents analytical and numerical techniques for evaluating two- and three-dimensional (3D) subsurface stress fields in anisotropic contacts. The subsurface stress results are required for evaluating contact fatigue life at damper contacts and dovetail attachment regions in single-crystal nickel-base superalloy turbine blades. An analytical procedure is presented for evaluating the subsurface stresses in the elastic half-space, based on the adaptation of a stress function method outlined by Lekhnitskii (1963, Theory of Elasticity of an Anisotropic Elastic Body, Holden-Day, Inc., San Francisco, pp. 1–40). Numerical results are presented for cylindrical and spherical anisotropic contacts, using finite element analysis. Effects of crystal orientation on stress response and fatigue life are examined. Obtaining accurate subsurface stress results for anisotropic single-crystal contact problems require extremely refined 3D finite element grids, especially in the edge of contact region. Obtaining resolved shear stresses on the principal slip planes also involves considerable postprocessing work. For these reasons, it is very advantageous to develop analytical solution schemes for subsurface stresses, whenever possible.

Development and Turbine Engine Performance of Three Advanced Rhenium Containing Superalloys for Single Crystal and Directionally Solidified Blades and Vanes

1997 ◽  
Author(s):  
Robert W. Broomfield ◽  
David A. Ford ◽  
Harry K. Bhangu ◽  
Malcolm C. Thomas ◽  
Donald J. Frasier ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Reliability ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Maximum Power ◽  
Team Approach ◽  
Air Cooling ◽  
Directionally Solidified ◽  
Turbine Engine ◽  
Nickel Base

Turbine inlet temperatures over the next few years will approach 1650°C (3000°F) at maximum power for the latest large commercial turbo fan engines, resulting in high fuel efficiency and thrust levels approaching 445 kN (100,000 lbs). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements and the development and use of rhenium (Re) containing high γ′ volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improve creep and thermo-mechanical fatigue strength but also environmental properties, including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4® containing 3% Re and CMSX®−10 containing 6% Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC® containing 3% Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50% of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines is scheduled to reach 60% in the U.S. ATS programme. Application experience to a total 1.3 million engine hours and 28,000 hours individual blade set service for CMSX-4 first stage turbine blades is reviewed for a small frame industrial engine.

Development and Turbine Engine Performance of Three Advanced Rhenium Containing Superalloys for Single Crystal and Directionally Solidified Blades and Vanes

1998 ◽  
Vol 120 (3) ◽  
pp. 595-608 ◽  
Author(s):  
R. W. Broomfield ◽  
D. A. Ford ◽  
J. K. Bhangu ◽  
M. C. Thomas ◽  
D. J. Frasier ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Reliability ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Maximum Power ◽  
Team Approach ◽  
Air Cooling ◽  
Directionally Solidified ◽  
Turbine Engine ◽  
Nickel Base

Turbine inlet temperatures over the next few years will approach 1650°C (3000°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching 445 KN (100,000 lbs.). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements, and the development and use of rhenium (Re) containing high γ′ volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improves creep and thermo-mechanical fatigue strength, but also environmental properties including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4® containing 3 percent Re and CMSX®-10 containing 6 percent Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC® containing 3 percent Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50 percent of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines are scheduled to reach 60 percent in the U. S. ATS programme. Application experience to a total 1.3 million engine hours and 28,000 hours individual blade set service for CMSX-4 first stage turbine blades is reviewed for a small frame industrial engine.

Low Cycle Fatigue of Single Crystal Nickel-Base Superalloy CMSX-4 Coated With a New Coating IC1

Materials ◽  
2005 ◽  
Author(s):  
Svjetlana Stekovic
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Ductile To Brittle Transition ◽  
Nickel Base ◽  
Oxidation And Corrosion ◽  
Base Superalloy

High strength nickel base superalloys have often been used in turbine blades because of their superior performances at high temperatures. One of them is CMSX-4, an ultra high strength, single crystal. CMSX-4 is a second generation rhenium-containing, nickel-base superalloy capable of high temperature and stress operations of at least 1150 °C [1]. The superalloy has limited oxidation and corrosion resistance at the high temperatures and to improve the oxidation and corrosion resistance, the base material is protected with coatings [2]. However, coatings exhibit a ductile-to-brittle transition temperature (DBTT) which causes early cracking of the coating and failure due to fatigue. The paper details low cycle fatigue (LCF) properties and degradation mechanisms of uncoated and IC1 coated single crystal CMSX-4. The tests were performed at two temperatures, 500 °C and 900 °C. Cylindrical solid specimens were cyclically deformed with fully reversed tension-compression loading with total strain amplitude control and at a constant strain rate of 10−4s−5 in air atmosphere without any dwell time. At 500 °C the coating has a detrimental effect on the fatigue life of CMSX-4 while at 900 °C IC1 does improve the fatigue life of the superalloy. The reduction of the fatigue life can be related to early cracking of the coating under its ductile to brittle transition temperature while the beneficial effect of the coating at 900 °C may be due to slower propagation of cracks caused by oxidation at the front of the crack tip.

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