Low-Cycle Fatigue Fracture Behavior of Superalloy GH4586 at Elevated Temperature

2004 ◽  
Vol 449-452 ◽  
pp. 337-340 ◽  
Author(s):  
Lei Wang ◽  
Tong Cui ◽  
Jun Ying Lü ◽  
Hong Cai Yang ◽  
Guang Pu Zhao
Keyword(s):  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Plastic Strain Amplitude ◽  
Cycle Fatigue ◽  
Cyclic Life ◽  
Creep Fatigue ◽  
Fatigue Fracture Behavior ◽  
Higher Sensitivity

Low-cycle fatigue property of superalloy GH4586 was investigated using a stress amplitude-controlled mode at 1023K. Fracture surface was examined with a scanning electronic microscopy. It was found that the cyclic life can be illustrated by Manson-Coffin at all strain levels. The fatigue cracks initiate primarily on the surface of the specimen. The plastic strain amplitude responded to the cyclic loading shows higher sensitivity than that of the elastic strain amplitude. It was demonstrated that the failure of the present alloy is in a manner of creep-fatigue feature.

Low Cycle Fatigue Behavior of As-Extruded AZ31 Magnesium Alloy

2011 ◽  
Vol 686 ◽  
pp. 202-207
Author(s):  
Ping Li Mao ◽  
Zheng Liu ◽  
Yang Li ◽  
Li Jia Chen
Keyword(s):  
Magnesium Alloy ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Az31 Alloy ◽  
Plastic Strain Amplitude ◽  
Az31 Magnesium Alloy ◽  
Total Strain Amplitude ◽  
Fracture Surfaces

The investigation on fatigue behavior and fracture surfaces of fatigued specimens of as-extruded AZ31 magnesium alloy can provide a reliable theoretical foundation for both fatigue resistant design and reasonable application of magnesium alloys. Through total-strain-amplitude controlled fatigue tests and analysis on fracture surfaces of fatigued specimens, the behavior of cyclic stress response and fatigue life as well as fracture mechanism were identified for as-extruded AZ31 magnesium alloy. The experimental results show that the extruded AZ31 alloy exhibits significant cyclic strain hardening, the relation between elastic strain amplitude, plastic strain amplitude and reversals to failure can be described by Basquin and Coffin-Manson equations respectively. In addition, it has been found that fatigue cracks initiate and propagate in a transgranular mode.

scholarly journals Low-cycle fatigue behavior of extruded Al-7Zn-2Mg-1.5Cu-0.2Sc-0.1Zr alloy at room and low temperatures

2018 ◽  
Vol 165 ◽  
pp. 22001
Author(s):  
Zhu Qingyan ◽  
Chen Lijia ◽  
Xu Chengji ◽  
Che Xin ◽  
Li Feng
Keyword(s):  
Low Temperature ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Aging Treatment ◽  
Cyclic Hardening ◽  
Strain Ratio ◽  
Plastic Strain Amplitude ◽  
Total Strain ◽  
Cycle Fatigue

Due to the low density and high specific strength, aluminum alloys have been considered for automotive and aerospace applications. The aluminum components usually service in the conditions of low temperature and dynamic loading. Therefore, the research on the low temperature fatigue performances of Al alloys has great significance. The lowcycle fatigue tests for the extruded Al-7Zn-2Mg-1.5Cu-0.2Sc-0.1Zr alloy subjected to solution plus aging treatment have been conducted at 25°C and -40°C, respectively. The strain ratio and cyclic frequency applied in the low-cycle fatigue test were -1 and 0.5Hz, respectively. The experimental results show that at 25°C, the alloy exhibits the cyclic hardening at the total strain amplitudes of 1.0% and 1.2%, and the cyclic stabilization at the total strain amplitudes of 0.4%, 0.6% and 0.8%. At -40°C, however, the cyclic stability is observed during whole fatigue deformation at the total strain amplitudes of 0.4%, 0.5%, 0.6%, 0.7% and 0.8%. The relationship between the elastic strain amplitude, plastic strain amplitude and reversals to failure can be described by Basquin and Coffin-Manson equations, respectively. In addition, the observation results of fatigue fracture surfaces reveal that the cracks initiate at the free surface of fatigue specimen and propagate in a transgranular mode.

M206 Dependence of Low-cycle Fatigue Behavior on Plastic Strain Amplitude in ECAPed Ferritic Stainless Steel

2015 ◽  
Vol 2015.90 (0) ◽  
pp. 280
Author(s):  
Ryuji TOMITA ◽  
Yoshihisa KANEKO ◽  
Makoto UCHIDA ◽  
Muhammad RIFAI ◽  
Hiroyuki MIYAMOTO ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Ferritic Stainless Steel ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Plastic Strain Amplitude ◽  
Cycle Fatigue

scholarly journals Low-Cycle Fatigue and Fracture Behavior of Aluminized Stainless Steel AISI 321 for Solar Thermal Power Generation Systems

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1089
Author(s):  
Wei Li ◽  
Lei Yang ◽  
Cong Li ◽  
Huitao Chen ◽  
Lu Zuo ◽  
...  
Keyword(s):  
Fracture Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Thermal Power ◽  
Fatigue Property ◽  
Cycle Fatigue ◽  
Al2o3 Layer ◽  
Aluminized Steel ◽  
Steel Aisi ◽  
Aisi 321

The microstructure, low-cycle fatigue property, and fracture behavior of as-received and aluminized steel were investigated at room temperature, respectively. The results reveal that the aluminized layer is mainly composed of three layers: (I) the external Al2O3 layer, (II) the transition Fe-Al mesophase layer, and (III) the diffusion layer with AlFe and AlCrFe phase. The microhardness of as-received steel lower than that of aluminized steel until the distance from aluminized layer is greater than 150 μm. Compared to the original steel, the aluminized steel exhibits lower stress amplitude and fatigue life, which is correlated to the surface integrity. According to the Coffin-Manson relationship, the fatigue-ductility coefficients for as-received and aluminized steel is 4.347 and 3.528, respectively. Fractographic analysis reveals that the fatigue cracks tend to nucleate at the coating and propagate through the grain boundaries apace.

Deformation and Fracture Analysis of a Duplex γ-TiAl Alloy during Low Cycle Fatigue

2007 ◽  
Vol 539-543 ◽  
pp. 1571-1576
Author(s):  
Wen Fang Cui ◽  
Chun Ming Liu ◽  
V. Bauer ◽  
Hans Jürgen Christ
Keyword(s):  
Strain Amplitude ◽  
Test Temperature ◽  
Tial Alloy ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Total Strain ◽  
Fracture Mechanisms ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Test Conditions

Isothermal low cycle fatigue (LCF) behaviours of a third generation titanium aluminide based γ-TiAl alloy with duplex microstructure were investigated under the various test conditions, including temperature (550°C-750°C), total strain amplitude (0.3%-0.6%) and environment (air and vacuum), in order to clarify the fatigue life, deformation characters and fracture process of the alloy during LCF. The plastic strain accumulation has a great contribution to LCF damage. With increasing total strain range, LCF life decreases distinctly. Under the small total strain amplitude (≤0.4%), the increase of test temperature enforces microstructure resistance to LCF fracture. However, the increase of test temperature together with large total strain amplitude (>0.5%) accelerates the microstructural degradation, which behaves the dissolution of α2 lamellae and recrystallization of γ phase, resulting in great LCF damage. Moreover, environment brittlement during high temperature exposure to air influences the initiation process of fatigue cracks. The fracture mechanisms at various test conditions were analyzed.

Cyclic Hardening Behavior of Extruded AZ31B Magnesium Alloy during Low Cycle Fatigue Process

2013 ◽  
Vol 395-396 ◽  
pp. 234-237
Author(s):  
Guo Sheng Duan ◽  
Bao Lin Wu ◽  
Xiang Zhao ◽  
Gang Zhao
Keyword(s):  
Magnesium Alloy ◽  
Dislocation Density ◽  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Strain Ratio ◽  
Plastic Strain Amplitude ◽  
Cycle Fatigue ◽  
Az31b Magnesium Alloy ◽  
Hardening Behavior

The strain-controlled fatigue tests on extruded AZ31B magnesium alloy were conducted under the uniaxial loading with strain ratio Rε=-∞, frequency of 0.1 Hz and strain amplitude of 2% at room temperature. The cyclic hardening behavior was investigated. It was found that, during the low cycle fatigue (LCF) process, as the number of cycles increases, the stress amplitude increases corresponding to the decrease of the plastic strain amplitude. The development of dislocation density can be described as the function of the number of fatigue cycles, and the behavior can be explained well based on the dislocation density development model.

Uniaxial Ratcheting and Low-Cycle Fatigue Failure of U75V Rail Steel

2016 ◽  
Vol 853 ◽  
pp. 246-250 ◽  
Author(s):  
Tao Fang ◽  
Qian Hua Kan ◽  
Guo Zheng Kang ◽  
Wen Yi Yan
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Rail Steel ◽  
Low Cycle Fatigue ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Ratcheting Strain ◽  
Cyclic Straining

Experiments on U75V rail steel were carried out to investigate the cyclic feature, ratcheting behavior and low-cycle fatigue under both strain- and stress-controlled loadings at room temperature. It was found that U75V rail steel shows strain amplitude dependent cyclic softening feature, i.e., the responded stress amplitude under strain-controlled decreases with the increasing number of cycles and reaches a stable value after about 20th cycle. Ratcheting strain increases with an increasing stress amplitude and mean stress, except for stress ratio, and the ratcheting strain in failure also increases with an increasing stress amplitude, mean stress and stress ratio. The low-cycle fatigue lives under cyclic straining decrease linearly with an increasing strain amplitude, the fatigue lives under cyclic stressing decrease with an increasing mean stress except for zero mean stress, and decrease with an increasing stress amplitude. Ratcheting behavior with a high mean stress reduces fatigue life of rail steel by comparing fatigue lives under stress cycling with those under strain cycling. Research findings are helpful to evaluate fatigue life of U75V rail steel in the railways with passenger and freight traffic.

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.

Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment for Various Strain Amplitude Levels

2009 ◽  
Author(s):  
Jean Alain Le Duff ◽  
Andre´ Lefranc¸ois ◽  
Jean Philippe Vernot
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Amplitude ◽  
Surface Finish ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Loading ◽  
Loading Conditions ◽  
Test Results ◽  
Cycle Fatigue

In February/March 2007, The NRC issued Regulatory Guide “RG1.207” and Argonne National Laboratory issued NUREG/CR-6909 that is now applicable in the US for evaluations of PWR environmental effects in fatigue analyses of new reactor components. In order to assess the conservativeness of the application of this NUREG report, Low Cycle Fatigue (LCF) tests were performed by AREVA NP on austenitic stainless steel specimens in a PWR environment. The selected material exhibits in air environment a fatigue behavior consistent with the ANL reference “air” mean curve, as published in NUREG/CR-6909. LCF tests in a PWR environment were performed at various strain amplitude levels (± 0.6% or ± 0.3%) for two loading conditions corresponding to a simple or to a complex strain rate history. The simple loading condition is a fully reverse triangle signal (for comparison purposes with tests performed by other laboratories with the same loading conditions) and the complex signal simulates the strain variation for an actual typical PWR thermal transient. In addition, two various surface finish conditions were tested: polished and ground. This paper presents the comparisons of penalty factors, as observed experimentally, with penalty factors evaluated using ANL formulations (considering the strain integral method for complex loading), and on the other, the comparison of the actual fatigue life of the specimen with the fatigue life predicted through the NUREG report application. For the two strain amplitudes of ± 0.6% and ± 0.3%, LCF tests results obtained on austenitic stainless steel specimens in PWR environment with triangle waveforms at constant low strain rates give “Fen” penalty factors close to those estimated using the ANL formulation (NUREG/6909). However, for the lower strain amplitude level and a triangle loading signal, the ANL formulation is pessimistic compared to the AREVA NP test results obtained for polished specimens. Finally, it was observed that constant amplitude LCF test results obtained on ground specimens under complex loading simulating an actual sequence of a cold and hot thermal shock exhibits lower combined environmental and surface finish effects when compared to the penalty factors estimated on the basis of the ANL formulations. It appears that the application of the NUREG/CR-6909 in conjunction with the Fen model proposed by ANL for austenitic stainless steel provides excessive margins, whereas the current ASME approach seems sufficient to cover significant environmental effects for representative loadings and surface finish conditions of reactor components.

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