Low Cycle Fatigue of FeAl (42 at. % Al) at Room Temperature

1996 ◽  
Vol 460 ◽  
Author(s):  
D. B. Hanes ◽  
R. Gibala
Keyword(s):  
Fatigue Life ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Surface Coatings ◽  
Protective Film ◽  
Cycle Fatigue ◽  
Environmental Embrittlement ◽  
Tension And Compression

ABSTRACTThe monotonie mechanical behavior in tension and compression of FeAl has been well documented. However, very little work has been done on the cyclic deformation behavior of this material. In this work, the behavior of FeAl (42 at. % Al) under low cycle fatigue was studied, including the effects of test environments and surface coatings. It was found that the fatigue life of this alloy is limited by environmental embrittlement. This embrittlement process can be equally well prevented by deformation in an oxygen environment or by coating the alloy with a protective film. The type of film applied appears to have little effect. Similar results were seen in monotonie testing.

Low Cycle Fatigue of 9-12% Cr Steel at Elevated Temperature: Cyclic Deformation Behavior and Life Assessment

2016 ◽  
Author(s):  
Peng Zhao ◽  
Fu-Zhen Xuan ◽  
De-Long Wu
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Life Assessment ◽  
Control Mode ◽  
Cycle Fatigue ◽  
Wide Range

Fatigue testing for an important turbine rotor material (X12CrMoWVNbN10-1-1 steel) was carried out over a wide range of strain and stress amplitudes at 873K. Particular attention was paid to the effect of control mode on the cyclic deformation behavior and life assessment at elevated temperature. Two main domains were observed depending both on the strain and stress amplitudes, where the effect of control mode was different. In the micro plastic deformation domain, the cyclic softening is slight and there is no clear difference in fatigue behavior between the stress and strain modes. In the plastic damage regime, stress cycling causes more significant softening or damage than strain cycling. The dependence of damage behavior on the evolution of dislocation substructure was focused. On the other hand, it is not possible to use strain based life model to predict fatigue life with the test results under a different control mode. A unified energy-based model is proposed based upon the deformation mechanism and the experimental results, which can assess the low cycle fatigue life with different control modes. The results obtained in this study could have significant implications in the design of structures.

scholarly journals Impact of Temperature on Low-Cycle Fatigue Characteristics of the HR6W Alloy

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6741
Author(s):  
Grzegorz Junak ◽  
Anżelina Marek ◽  
Michał Paduchowicz
Keyword(s):  
Fatigue Life ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Fatigue Characteristics

This paper presents the results of tests conducted on the HR6W (23Cr-45Ni-6W-Nb-Ti-B) alloy under low-cycle fatigue at room temperature and at 650 °C. Fatigue tests were carried out at constant values of the total strain ranges. The alloy under low-cycle fatigue showed cyclic strengthening both at room temperature and at 650 °C. The degree of HR6W strengthening described by coefficient n’ was higher at higher temperatures. At the same time, its fatigue life Nf at room temperature was, depending on the range of total strain adopted in the tests, several times higher than observed at 650 °C.

Cyclic Deformation and Buckling Behavior of Pipe With Local Metal Loss Subjected to Seismic Ground Motion

2011 ◽  
Author(s):  
Masaki Mitsuya ◽  
Hiroshi Yatabe
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Earthquake Resistance ◽  
Metal Loss ◽  
Cycle Fatigue ◽  
Longitudinal Length

Buried pipelines may be deformed due to earthquakes and also corrode despite corrosion control measures such as protective coatings and cathodic protection. In such cases, it is necessary to ensure the integrity of the corroded pipelines against earthquakes. This study developed a method to evaluate the earthquake resistance of corroded pipelines subjected to seismic ground motions. Axial cyclic loading experiments were carried out on line pipes subjected to seismic motion to clarify the cyclic deformation behavior until buckling occurs. The test pipes were machined so that each one would have a different degree of local metal loss. As the cyclic loading progressed, displacement shifted to the compression side due to the formation of a bulge. The pipe buckled after several cycles. To evaluate the earthquake resistance of different pipelines, with varying degrees of local metal loss, a finite-element analysis method was developed that simulates the cyclic deformation behavior. A combination of kinematic and isotropic hardening components was used to model the material properties. These components were obtained from small specimen tests that consisted of a monotonic tensile test and a low cycle fatigue test under a specific strain amplitude. This method enabled the successful prediction of the cyclic deformation behavior, including the number of cycles required for the buckling of pipes with varying degrees of metal loss. In addition, the effect of each dimension (depth, longitudinal length and circumferential width) of local metal loss on the cyclic buckling was studied. Furthermore, the kinematic hardening component was investigated for the different materials by the low cycle fatigue tests. The kinematic hardening components could be regarded as the same for all the materials when using this component as the material property for the finite-element analyses simulating the cyclic deformation behavior. This indicates that the cyclic deformation behavior of various line pipes can be evaluated only based on their respective tensile properties and common kinematic hardening component.

Low Cycle Fatigue of Nuclear Pipe Components

1974 ◽  
Vol 96 (3) ◽  
pp. 171-176 ◽  
Author(s):  
J. D. Heald ◽  
E. Kiss
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Room Temperature ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
304 Stainless Steel ◽  
Code Design ◽  
Hydraulic Pressure ◽  
Cycle Fatigue ◽  
Cyclic Bending

This paper presents the results of low-cycle fatigue testing and analysis of 26 piping components and butt-welded sections. The test specimens were fabricated from Type-304 stainless steel and carbon steel, materials which are typically used in the primary piping of light water nuclear reactors. Components included 6-in. elbows, tees, and girth butt-welded straight sections. Fatigue testing consisted of subjecting the specimens to deflection-controlled cyclic bending with the objective of simulating system thermal expansion type loading. Tests were conducted at room temperature and 550 deg F, with specimens at room temperature subjected to 1050 psi constant internal hydraulic pressure in addition to cyclic bending. In two tests at room temperature, however, stainless steel elbows were subjected to combined simultaneous cyclic internal pressure and cyclic bending. Predictions of the fatigue life of each of the specimens tested have been made according to the procedures specified in NB-3650 of Section III[1] in order to assess the code design margin. For the purpose of the assessment, predicted fatigue life is compared to actual fatigue life which is defined as the number of fatigue cycles producing complete through-wall crack growth (leakage). Results of this assessment show that the present code fatigue rules are adequately conservative.

Microstructural Effects on Low Cycle Fatigue of Sn-3.8Ag-0.7Cu Pb-Free Solder

2007 ◽  
Vol 345-346 ◽  
pp. 239-242
Author(s):  
Qiu Lian Zeng ◽  
Zhong Guang Wang ◽  
J.K. Shang
Keyword(s):  
Fatigue Life ◽  
Cyclic Deformation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fracture Mechanisms ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Equiaxed Microstructure ◽  
Cyclic Frequency ◽  
Microstructural Effects

Low cycle fatigue behavior of Sn-3.8Ag-0.7Cu solder was investigated under fully reversed cyclic loading, with particular emphasis on microstructural effects. The LCF behavior of the solder with equiaxed microstructure was found to differ greatly from that of the solder with a dendrite microstructure. At a given total strain amplitude, the dendrite microstructure exhibited a much longer fatigue life than the equiaxed microstructure. Such a strong microstructural effect on fatigue life arose from the difference in cyclic deformation and fracture mechanisms between the two microstructures. A large number of microcracks along grain boundaries of the equiaxed structure solder developed with increasing cycling, while for the dendrite structure solder, cyclic deformation took place along the direction of the maximal shear stress during fatigue tests and microcracks initiated and propagated along shear deformation bands. Besides, the fatigue behavior of the dendritic microstructure was very sensitive to cyclic frequency whereas the fatigue behavior of the equiaxed microstructure showed less sensitivity to cyclic frequency.

Cyclic deformation behavior of HAYNES® HR-120® superalloy under low-cycle fatigue loading

2004 ◽  
Vol 36 (1-2) ◽  
pp. 85-98 ◽  
Author(s):  
L.J. Chen ◽  
P.K. Liaw ◽  
H. Wang ◽  
Y.H. He ◽  
R.L. McDaniels ◽  
...  
Keyword(s):  
Cyclic Deformation ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue

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.

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