Investigation on Material's Fatigue Property Variation Among Different Regions of Directional Solidification Turbine Blades—Part I: Fatigue Tests on Full Scale Blades

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Xiaojun Yan ◽  
Xia Chen ◽  
Ruijie Sun ◽  
Ying Deng ◽  
Lianshan Lin ◽  
...  
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Directional Solidification ◽  
Turbine Blades ◽  
Fatigue Property ◽  
Full Scale ◽  
Fatigue Properties ◽  
Casting Method ◽  
Property Variation ◽  
Conventional Casting

At present, directional solidification (DS) made blades are commonly used in high performance turbine for their better high temperature mechanical, especially in creep properties compared with the equiaxed grain (EG) blades made by conventional casting method. To predict DS blades' fatigue life accurately, one of the practical ways is to conduct tests on full-scale blades in a laboratory/bench environment. In this investigation, two types of full scale turbine blades, which are made from DZ22B by DS method and K403 by conventional casting method, respectively, were selected to conduct high temperature combined low and high cycle fatigue (CCF) tests on a special design test rig, to evaluate the increase of fatigue life benefitted from material change. Experimental results show that different from EG blades, DS blades' fracture section is not located on the position where the maximum stress point lies. By comparing fatigue test results of the two types of blade, it can be found that the fatigue properties among different regions of the DS blade are different, and its fatigue damage is not only related to the stress field, but also affected by different parts material's fatigue properties.

Investigation on Material's Fatigue Property Variation Among Different Regions of Directional Solidification Turbine Blades—Part II: Fatigue Tests on Bladelike Specimens

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Xiaojun Yan ◽  
Mingjing Qi ◽  
Ying Deng ◽  
Xia Chen ◽  
Ruijie Sun ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Maximum Stress ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Full Scale ◽  
Test Results ◽  
Property Variation ◽  
Stress Region

Part I of this investigation is mainly focused on fatigue tests of full scale turbine blades, based on the observation of the phenomena that some directional solidification (DS) blades do not fracture at their maximum stress region, and it has been revealed that there exists material's fatigue property variation among different regions of DS blades. For more in-depth and quantitative study on the fatigue property variation, Part II of this investigation designs and fabricates four types of DS bladelike specimens (including platform-, shroud-, body-, and rootlike specimens), which imitate the geometry, microstructure, and stress features of a full scale turbine blade on its four typical regions, to conduct the low cycle fatigue (LCF) tests. Test results show that the bodylike specimen has the best fatigue performance, and under the same stress state, the fatigue life of root-, shroud-, and platformlike specimens are 29.1%, 28.5%, and 13.7% of the bodylike specimen, respectively. The large material's fatigue property variation among different regions of DS blades should be considered in future blade life design.

Fatigue Properties of a Ni-Base Superalloy Treated by Laserolazing

1986 ◽  
Vol 80 ◽  
Author(s):  
Jiang Xiaoping ◽  
Hu Zhuang Qi ◽  
Shih Changxu ◽  
Zhu Guizeng ◽  
Meng Qinglin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Turbine Blades ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Boundary Carbide ◽  
Post Heat Treatment ◽  
Before And After ◽  
Vibration Fatigue ◽  
Base Superalloy

AbstractFatigue properties of a wrought Ni-base superalloy treated by laserglazing and post heat treatments have been investigated. Tests have been run both by the rotating bend fatigue at 700°C and the vibration fatigue of turbine blades at room temperature. The results showed that the fatigue property of laserglazed specimens was obviously deteriorated because of resolution of γ′ phase and grain boundary carbide, interdendritic segregation of TiC and microcrack caused by thermal stress. However, suitable preheating and post heat treatment added before and after laserglazing can eliminate these defects and recover the fatigue life of this superalloy. Selected laser processing technology was applied to repairing blades rejected due to microcracks at trailing edge. The vibration fatigue life of blades repaired by laserglazing and post heat treatment was over two times as high as that of normal used blades with same service time.

scholarly journals Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Chao Gu ◽  
Min Wang ◽  
Yanping Bao ◽  
Fuming Wang ◽  
Junhe Lian
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Critical Size ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Bearing Steel ◽  
Fatigue Properties ◽  
Bearing Steels ◽  
Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

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.

Assessment of Fatigue Life for High-Temperature Pipeline Welds Using X-Ray Diffraction Technique

2007 ◽  
Vol 353-358 ◽  
pp. 130-133
Author(s):  
Keun Bong Yoo ◽  
Jae Hoon Kim
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Diffraction Method ◽  
Life Assessment ◽  
Fatigue Properties ◽  
X Ray Diffraction ◽  
X Ray

The objective of this study is to examine the feasibility of the X-ray diffraction method for the fatigue life assessment of high-temperature steel pipes used for main steam pipelines, re-heater pipelines and headers etc. in power plants. In this study, X-ray diffraction tests were performed on the specimens simulated for low cycle fatigue damage, in order to estimate fatigue properties at the various stages of fatigue life. As a result of X-ray diffraction tests, it was confirmed that the full width at the half maximum (FWHM) decreased with an increase in the fatigue life ratio, and that the FWHM and the residual stress due to fatigue damage were algebraically linearly related to the fatigue life ratio. From this relationship, a direct assessment of the remaining fatigue life was feasible.

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.

Effect of Laser Shock Peening on Fatigue Life of Full Scale Turbine Blades

2017 ◽  
Author(s):  
Cao Chen ◽  
Xiaoyong Zhang ◽  
Lei Han ◽  
Xiaojun Yan
Keyword(s):  
Yield Stress ◽  
Turbine Blades ◽  
Treatment Method ◽  
Full Scale ◽  
Laser Shock Peening ◽  
Fatigue Properties ◽  
Laser Shock ◽  
Total Stress ◽  
Safe Life ◽  
Shock Peening

Laser shock peening (LSP) is a promising surface treatment method for improving fatigue properties of turbine blades. The effect of LSP on combined low and high cycle fatigue (CCF) life of full scale turbine blade was investigated. The LSP is performed by YLSS-40 LSP equipment and the laser power density is 5.8 GW/cm2. Thirteen LSP treated turbine blades and thirteen untreated turbine blades were selected to carry out the contrast test at high temperature in a bench environment. Experimental results show that there exists a critical vibration stress of blades, below which the CCF life was significantly prolonged by LSP, and above which the LSP has no effect or an adverse effect on the CCF life. The safe life of blades can be significantly increased after treated by LSP when the total stress is below the yield stress. However, the situation is a bit different when the total stress is above the yield stress. Although the safe life of LSP blades is longer than that of untreated blades in this situation, but the median life of blades is decreased after treated by LSP. The effect of LSP on the scatter in life plays a greater role in improving the safe life that directly leads to the safe life of LSP blades longer than the safe life of untreated blades when the total stress is above the yield stress.

Creep-Fatigue Tests on Full Scale Directionally Solidified Turbine Blades

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Xiaojun Yan ◽  
Jingxu Nie
Keyword(s):  
Fatigue Life ◽  
Test Data ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Full Scale ◽  
Life Assessment ◽  
Directionally Solidified ◽  
Creep Fatigue ◽  
Life Tests

A new experimental method, in which a full scale directionally solidified (DS) alloy turbine blade is loaded by a special design rig employing friction force and heated by eddy current induction, is proposed to conduct creep-fatigue life tests in this investigation. The method can take factors such as geometry, volume, especially cast procedures, etc., into creep-fatigue life assessment. Principle and design of the test rig are fully explained. Creep-fatigue tests of turbine blades made of DZ4 alloy (one type of DS alloys) were conducted and test data were analyzed. Life prediction based on test data of this investigation shows good agreement with actual flight experience of these blades. The method of this article provides a new way to estimate the potential creep-fatigue or low cycle fatigue life for turbine blades.

Effect of Minor Sc and Zr on the Fatigue Properties of Al-Mg-Mn Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 863-866
Author(s):  
Yong Yi Peng ◽  
Zhi Min Yin ◽  
Bo Nie ◽  
Tao Wang
Keyword(s):  
Electron Microscope ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Control Experiment ◽  
Fatigue Property ◽  
Optical Microscope ◽  
Fatigue Properties ◽  
Transmission Electron ◽  
Electronic Microscope ◽  
Zr Alloy

The effect of Sc and Zr on the fatigue property of Al-6.2Mg-0.4Mn alloy was investigated by control experiment; the fatigue lives of Al-6.2Mg-0.4Mn alloy with and without Sc and Zr at different loading stress amplitudes were measured. The relationships between their fatigue properties and microstructures were studied by means of optical microscope, scanning electronic microscope and transmission electron microscope. The addition of Sc and Zr improved the fatigue lives and fatigue strength of Al-6.2Mg-0.4Mn alloy. It is difficult for crack to initiate and propagate in the Al-6.2Mg-0.4Mn-Sc-Zr alloy. The fine and pancake-like grains of this alloy lead to the increase of fatigue life and fatigue strength. The high densities of dislocation and grain boundary in the Al-6.2Mg-0.4Mn-Sc-Zr alloy can prevent microcrack from propagating effectively. Additionally the dispersion precipitation of Al3Sc and Al3(Sc1-xZrx) particles enhance the toughness of Al-6.2Mg-0.4Mn-Sc-Zr alloy.

Changes of Fatigue Property with Heat Exposure in INVAR/AW Wire

2005 ◽  
Vol 475-479 ◽  
pp. 1873-1876
Author(s):  
Shang Shu Kim ◽  
Su Dong Park ◽  
Byung Geol Kim ◽  
Hee Woong Lee ◽  
Goo Yong Sin ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Yield Strength ◽  
Life Span ◽  
Fatigue Limit ◽  
Outer Surface ◽  
Heat Exposure ◽  
Fatigue Property ◽  
Fatigue Properties ◽  
Stable Operation

Fatigue properties of INVAR/AW wires have been investigated under the heat exposure in order to ensure stable operation and to estimate life span of their power line. In the case of heat exposure for 1000hr, fatigue life and limit increased. For further heat exposure, fatigue limit decreased due to the decrease in yield strength. The variation fatigue of strand wire was strongly dependent on its amplitude. Also, cracks in wires of 7 strands were caused by stress concentration at the outer surface and fretting between each wire during vibration.

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