Low Cycle Fatigue Behavior of TA29 Titanium Alloy at Different Temperatures

The low cycle fatigue behaviour of TA29 titanium alloy blisk forging at 300°C, 400°C, 500°C, 600°C were studied. The cyclic stress response, the stress-strain behaviour, the fatigue life and the fractograph were observed and analyzed. Through the double logarithm linear regression, the Coffin-Manson model parameters of TA29 titanium alloy at different temperatures were obtained. The results showed that the fatigue life decreases as the strain amplitude increases. Also, the testing temperature has a significant effect on the low cycle fatigue properties of TA29 titanium alloy. At the same level of the strain amplitude, the fatigue life and the peak value of cyclic stress decrease, while the plastic strain component in total strain amplitude increases with the increase of testing temperature. On the basis of the fractograph of fatigue specimens, the initiation of crack is mainly on the surface of the specimen. Fatigue striations can be seen clearly at fatigue crack propagation area. The fatigue striations in stable fatigue crack propagation area were broadened, and the propagation area was reduced and the final rupture area was increased with the increase of testing temperature.

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Analysis on Low Cycle Fatigue Life and Fatigue Fracture Surface Morphology of TC25 Titanium Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.697.652 ◽

2016 ◽

Vol 697 ◽

pp. 652-657

Author(s):

Rong Guo Zhao ◽

Yi Yan ◽

Yong Zhou Jiang ◽

Xi Yan Luo ◽

Qi Bang Li ◽

...

Keyword(s):

Titanium Alloy ◽

Fatigue Crack ◽

Fatigue Life ◽

Fracture Surface ◽

Crack Growth ◽

Fatigue Fracture ◽

Low Cycle Fatigue ◽

Observation System ◽

Cycle Fatigue ◽

Stress Strain

At room temperature, the low cycle fatigue tests for smooth specimens of TC25 titanium alloy under various stress ranges are operated at a CSS280I-20w Electro Hydraulic Servo Universal Testing Machine with a microscopic observation system, and the low cycle fatigue lifetimes are measured. Based upon the analysis of stress-strain hysteresis loop of low cycle fatigue of TC25 titanium alloy, a simplified Manson-Coffin formula is derived according to both the experimental characteristics and the stress-strain constitutive model, the fatigue lifetimes are plotted against stress ranges, and a stress-fatigue life curve for TC25 titanium alloy is obtained by the linear regression analysis method. Finally, the fracture surface morphologies of TC25 specimens are investigated using a JSM-6360 Scanning Electron Microscopy, and the fatigue fracture mechanisms of low cycle fatigue are studied. It shows that the plastic deformations are mainly formed at the accelerated fracture stage, and various shear lips can be observed on the fracture surfaces, which demonstrates that the shear stress results in the final rupture of TC25 titanium alloy. During the fracture of low cycle fatigue, the cleavage nucleation leads to the formation of fatigue crack initiation region, the fatigue crack growth exhibits a mixed transgranular and intergranular crack growth mode, and in the final rupture region, the fracture surface of low cycle fatigue of TC25 titanium alloy appears as a typical semi-brittle fracture mode.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.853.246 ◽

2016 ◽

Vol 853 ◽

pp. 246-250 ◽

Cited By ~ 2

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.

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LOW CYCLE FATIGUE BEHAVIOR AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194512003261 ◽

2012 ◽

Vol 06 ◽

pp. 251-256

Author(s):

HO-YOUNG YANG ◽

JAE-HOON KIM ◽

KEUN-BONG YOO

Keyword(s):

Fatigue Life ◽

Strain Energy ◽

Life Prediction ◽

Prediction Models ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Total Strain ◽

Cycle Fatigue ◽

Total Strain Range ◽

Different Temperatures

Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. 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 Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

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High-Strength Reinforcing Steel Bars: Low Cycle Fatigue Behavior Using RGB Methodology

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-021-00474-9 ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Jorge E. Egger ◽

Fabian R. Rojas ◽

Leonardo M. Massone

Keyword(s):

Fatigue Life ◽

Strain Amplitude ◽

Low Cycle Fatigue ◽

High Strength ◽

Image Correlation ◽

Total Strain ◽

Total Strain Amplitude ◽

Reinforcing Steel ◽

Cycle Fatigue ◽

Steel Bars

AbstractLow cycle fatigue life of high-strength reinforcing steel bars (ASTM A706 Grade 80), using photogrammetry by RGB methodology is evaluated. Fatigue tests are performed on specimens under constant axial displacement with total strain amplitudes ranging from 0.01 to 0.05. The experimental observations indicate that buckling of high-strength reinforcing bars results in a damaging degradation of their fatigue life performance as the slenderness ratio increases, including an early rebar failure as the total strain amplitude increases since it achieves the plastic range faster. In addition to this, the results show that the ratio of the ultimate tensile strength to yield strength satisfies the minimum of 1.25 specified in ASTM A706 for reinforcement. On the other hand, the RGB methodology indicates that the axial strains measured by photogrammetry provide more accurate data since the registered results by the traditional experimental setup do not detect second-order effects, such as slippage or lengthening of the specimens within the clamps. Moreover, the RGB filter is faster than digital image correlation (DIC) because the RGB methodology requires a fewer computational cost than DIC algorithms. The RGB methodology allows to reduce the total strain amplitude up to 45% compared to the results obtained by the traditional setup. Finally, models relating total strain amplitude with half-cycles to failure and total strain amplitude with total energy dissipated for multiple slenderness ratios (L/d of 5, 10, and 15) are obtained.

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