Low-Cycle Fatigue under Biaxial Stress

1974 ◽  
Vol 188 (1) ◽  
pp. 657-671 ◽  
Author(s):  
M. W. Parsons ◽  
K. J. Pascoe
Keyword(s):  
Austenitic Steel ◽  
Abrupt Change ◽  
Low Cycle Fatigue ◽  
Axial Loading ◽  
Strain Range ◽  
Fatigue Behaviour ◽  
Biaxial Stress ◽  
Cycle Fatigue ◽  
Biaxial Strain ◽  
Total Strain Range

The low-cycle fatigue behaviour of a ferritic and an austenitic steel have been studied under various conditions of reversed biaxial strain. These cyclically softened and hardened respectively. In all cases, relationships of the form were found between total strain range Δε t and life Nf for lives in the range 102−105 cycles, with an abrupt change of β at intermediate lives. Variation of state of strain affected both β and κ. Various theories for the correlation of fatigue behaviour under multi-axial loading have been reviewed and compared with these results. None was found to account adequately for the effect of straining régime with the materials tested.

Low Cycle Fatigue Characteristics of a Low-Thermal Expansion, High Strength Alloy (HAYNES 242 Alloy)

2011 ◽  
Author(s):  
L. M. Pike ◽  
S. K. Srivastava
Keyword(s):  
Thermal Expansion ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
High Strength ◽  
Wave Form ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Low Thermal Expansion ◽  
Long Range Ordering

HAYNES® 242® alloy, based primarily on the Ni-25Mo-8Cr system, derives its low thermal expansion characteristics from its composition and its high strength concomitant with high ductility from a long-range ordering reaction upon an aging heat treatment. This combination has enabled the alloy continually to find a challenging range of applications in the aerospace industry at up to 1300°F (704°C). These include seal rings, containment rings, duct segments, casings, rocket nozzles, etc. In conjunction with the creep strength and environmental resistance, the low cycle fatigue (LCF) behavior is an important material property affecting the service life of 242 alloy components. The low cycle fatigue behavior of 242 alloy was studied under fully reversed strain-controlled mode at 800°F (427°C), 1000°F (538°C), 1200°F (649°C) and 1400°F (760°C) using a triangular wave form with a frequency of 0.33 Hz. Results are presented in terms of cycles to crack initiation and failure. The magnitudes of fatigue lives at total strain range ≤ 0.7% at 800, 1000 and 1200°F are significantly greater than those of solid solution strengthened alloys. Additionally, stress-controlled LCF tests were performed at 1200°F (649°C) on 242 alloy as well as 909 alloy (for comparison). The paper will discuss the results of these two test programs.

Effect of Creep in Low-Cycle Fatigue of Pressure Vessel Steel

1970 ◽  
Vol 92 (1) ◽  
pp. 67-73 ◽  
Author(s):  
J. Dubuc ◽  
A. Biron
Keyword(s):  
Pressure Vessel ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Pressure Vessel Steel ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Vessel Steel ◽  
The Mean ◽  
Mean Strain

Low-cycle fatigue tests have been carried out at 2 cpm on a pressure vessel steel at 350 deg C (662 deg F). The total strain range was fixed for each test and the minimum (or mean) strain in some cases was constant (zero minimum value), in others increased uniformly in time at a predetermined rate. It was found that variations in the mean strain up to 0.5 percent/hour had no significant influence on the results.

Notch Effect in Low-Cycle Fatigue at Elevated Temperatures—Life Prediction From Crack Initiation and Propagation Considerations

1986 ◽  
Vol 108 (4) ◽  
pp. 279-284 ◽  
Author(s):  
Masao Sakane ◽  
Masateru Ohnami
Keyword(s):  
Crack Initiation ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Notch Effect ◽  
Cycle Fatigue ◽  
Crack Initiation And Propagation ◽  
Total Strain Range ◽  
Notched Specimens ◽  
Initiation And Propagation

This paper describes the notch effect in low-cycle fatigue of an austenitic stainless steel SUS 304 at 873 K in air. Total strain range-controlled tests were carried out using a round unnotched and three round notched specimens. A prediction method for low-cycle fatigue lives of notched specimens was developed by predicting the crack initiation and propagation periods separately. To predict the former Neuber’s rule was applied and a nominal stress/strain criterion was developed to predict the latter. Failure lives, obtained by adding the two prediction lives, closely agree with observed failure lives.

scholarly journals Low-Cycle Fatigue Behaviour of a Ni-Based Single-Crystal Superalloy

2014 ◽  
Vol 891-892 ◽  
pp. 416-421 ◽  
Author(s):  
Mikael Segersäll ◽  
Johan Moverare ◽  
Daniel Leidermark ◽  
Kjell Simonsson
Keyword(s):  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Fatigue Behaviour ◽  
Single Crystal Superalloy ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Tension Compression Asymmetry

In this study, low-cycle fatigue (LCF) tests at 500 °C in the <001>, <011> and <111> directions have been performed for the Ni-based single-crystal superalloy MD2. All tests were carried out in strain control with Rε=-1. The <001> direction has the lowest stiffness of the three directions and also shows the best fatigue properties in this study followed by the <011> and <111> directions, respectively. It is well recognised that Ni-based single-crystal superalloys show a tension/compression asymmetry in yield strength and this study shows that a tension/compression asymmetry also is prevalent during LCF conditions. At mid-life, the <001> direction generally has a higher stress in tension than in compression, while the opposite is true for the <011> direction. For the <111> direction the asymmetry is found to be strain range dependent. The <011> and <111> directions show a cyclic hardening behaviour when comparing cyclic stress-strain curves with monotonic stress-strain curves. In addition, the <011> and <111> directions show a serrated yielding behaviour for a number of cycles while the yielding of the <001> direction is more stable.

Low Cycle Fatigue of Alloy 617 at 850 °C and 950 °C

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
J. K. Wright ◽  
L. J. Carroll ◽  
J. A. Simpson ◽  
R. N. Wright
Keyword(s):  
Strain Rate ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Solute Drag ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Total Strain Range ◽  
Cycles To Failure

The low cycle fatigue behavior of Alloy 617 has been evaluated at 850 °C and 950 °C, the temperature range of particular interest for the intermediate heat exchanger on a proposed high-temperature gas-cooled nuclear reactor. Cycles to failure were measured as a function of total strain range and varying strain rate. Results of the current experiments compare well with previous work reported in the literature for a similar range of temperatures and strain rate. The combined data demonstrate a Coffin–Manson relationship, although the slope of the Coffin–Manson fit is close to −1 rather than the typically reported value of −0.5. At 850 °C and a strain rate of 10−3 /s Alloy 617 deforms by a plastic flow mechanism in low cycle fatigue and exhibits some cyclic hardening. At 950 °C for strain rates of 10−3–10−5 /s, Alloy 617 deforms by a solute drag creep mechanism during low cycle fatigue and does not show significant cyclic hardening or softening. At this temperature the strain rate has little influence on the cycles to failure for the strain ranges tested.

Low Cycle Fatigue Life Evaluation According to Temperature and Orientation in Nickel-Base Superalloy

2019 ◽  
Vol 814 ◽  
pp. 121-126
Author(s):  
In Kang Heo ◽  
Dong Hyun Yoon ◽  
Jae Hoon Kim
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Total Strain ◽  
Nickel Base Superalloy ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Materials Used ◽  
Nickel Base

Components of gas turbines must be extremely resistant to high temperatures, high stresses, high-temperature corrosion, and erosive environments. The materials used in these environmental conditions are mainly nickel-based superalloys. In this study, the low-cycle fatigue of the nickel-based superalloy Inconel 792 was examined. The total strain range of a gas turbine between 760 °C and 870 °C was considered as the parameter representing the actual gas turbine operation. In addition, tests were performed using a trapezoidal waveform of the total strain to reflect the operation-stop conditions of a gas turbine with frequent shutdowns. The results of the fatigue test were compared with the Coffin–Manson method and energy method. The fractured surface was analyzed using a scanning electron microscope (SEM).

Biaxial Low Cycle Fatigue of Unaged and Aged 1Cr-1Mo-1/4V Steels at Elevated Temperature

1991 ◽  
Vol 113 (2) ◽  
pp. 244-253 ◽  
Author(s):  
M. Sakane ◽  
M. Ohnami ◽  
M. Sawada
Keyword(s):  
Elevated Temperature ◽  
Low Cycle Fatigue ◽  
Biaxial Stress ◽  
Cycle Fatigue ◽  
Biaxial Strain ◽  
Data Correlation ◽  
Biaxial Fatigue ◽  
Fatigue Data ◽  
Effective Stress Parameter ◽  
Stress Parameters

This paper describes the biaxial low cycle fatigue of unaged and aged 1Cr-1Mo-1/4V rotor steels at 823 K in air. Combined push-pull and reversed torsion tests were carried out on these steels and the biaxial fatigue data were obtained. Aging significantly reduced the hardness of the steel but had no effect on the crack direction in biaxial low cycle fatigue. Aging also had no effect on the data correlation using the biaxial strain parameters, but had a significant effect on the data correlation using the biaxial stress parameters. The change in the effective stress parameter in correlating the biaxial fatigue data due to aging is discussed in connection with the material softening.

scholarly journals A review of low-cycle fatigue of Alloy 617 for use in VHTR components: Experimental outlook

2018 ◽  
Vol 159 ◽  
pp. 02049 ◽  
Author(s):  
Rando Tungga Dewa ◽  
Jeong-Hun Park ◽  
Seon-Jin Kim ◽  
Woo-Gon Kim ◽  
Eung-Seon Kim ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxidation Behavior ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Surface Cracking ◽  
The Matrix ◽  
Lower Temperature

The effect of strain range and temperature on the low-cycle fatigue behaviour and microstructure change during cyclic deformation of Alloy 617 for use in very high temperature gas-cooled reactor components were studied at elevated temperature starting from ambient condition. Increasing the strain range and the temperature was noticed to reduce the fatigue resistance of nickel-based Alloy 617 due to facilitating the transformation behavior of the carbides in the grain interior, precipitates along the grain boundary, and oxidation behavior inducing surface connected precipitates cracking. Initial hardening behavior was observed at room temperature condition during cyclic due to the pile-up dislocation of micro-precipitates. The grain size was also taking a role due to the formation of an obstacle in the matrix. In the high temperature regime, the alloy 617 was found to soften for its entire life due to the fast recovery deformation, proved by its higher plasticity compared with lower temperature. The deformation behavior also showing high environmentally assisted damage. Oxidation behavior was found to become the primary crack initiation, resulting in early intergranular surface cracking.

Investigation on Low Cycle Fatigue Life of SC Notched Specimens

2010 ◽  
Vol 97-101 ◽  
pp. 449-452
Author(s):  
Ping Zhao ◽  
Qing Hua He ◽  
Wei Li
Keyword(s):  
Fatigue Life ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Notched Specimens ◽  
Orientation Function ◽  
Fatigue Notch Factor

A low cycle fatigue life (LCF) prediction model for nickel-based single crystal (SC) is presented based on the LCF experiments of notched specimens. Fatigue notch factor is adopted to reflect the influence of notch shape on LCF. Orientation function is adopted to modify total strain range and eliminate the influence of orientation on LCF. Cycle stress ratio is adopted to reflect the influence of mean stress and cycle character on LCF. The predicted results shows that all the data are in the factor of 2.1 scatter band, which means that the model proposed in this work is reasonable.

Low-Cycle Fatigue Behavior of Internally Pressurized Boxes

1967 ◽  
Vol 89 (3) ◽  
pp. 427-435 ◽  
Author(s):  
M. R. Gross ◽  
R. E. Heise
Keyword(s):  
Aluminum Alloy ◽  
Yield Strength ◽  
Thick Plate ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Complex Structures ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Structural Applications

One phase of a continuing study of the low-cycle fatigue behavior of metals for deep submergence structural applications involves the validity of simple specimen results when applied to complex structures. As a part of this study, the low-cycle fatigue performance of twelve internally pressurized boxes was investigated. The boxes were constructed from 1-in-thick plate of six materials consisting of three steels, one aluminum alloy, and two titanium alloys. The boxes were cyclically pressurized at peak nominal stresses up to about 80 percent of the yield strength of the base metal. The results are compared with data previously obtained for simple laboratory specimens. The results of the box tests tend to confirm two general conclusions reached previously from simple specimen tests, that is: (1) Increases in low-cycle fatigue strength for a given life are not commensurate with increases in yield strength, and (2) low-cycle fatigue life is closely related to total strain range and appears to be independent of both structural metal and strength level in the life range of 1000 to 30,000 cycles.

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