ANISOTROPY OF LOW CYCLE FATIGUE CHARACTERISTICS OF SINGLE-CRYSTAL HEAT-RESISTANT NICKEL ALLOYS

2020 ◽  
pp. 97-105
Author(s):  
I.A. Hodinev ◽  
◽  
S.A. Monin ◽  
Keyword(s):  
Single Crystal ◽  
Nickel Alloys ◽  
Endurance Limit ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Heat Resistant ◽  
Cycle Loading ◽  
Two Temperatures ◽  
Fatigue Characteristics ◽  
Complete Deformation

The low cycle fatigue of heat-resistant nickel alloys with a single crystal structure VZHM7 and VIN3 was studied. The tests were carried out under conditions of monitoring the complete deformation in the cycle, loading of the type «tension-compression» occurred according to a sinusoidal law with a frequency of 0,5 Hz. For both alloys, tests were carried out for three crystallographic orientations ([001], [011], [111]) at two temperatures: 500 and 850 °C. Regression lines were constructed, the limits of limited endurance were found on the basis of 104 cycles. The influence of test temperature and crystallographic orientation on the endurance limit of alloys and RMS is analyzed.

scholarly journals Influence of Hardened Surface on Low Cycle Fatigue Characteristics at Tension-compression and Bending

2015 ◽  
Vol 63 (5) ◽  
pp. 1549-1554
Author(s):  
Artüras Sabaliauskas ◽  
Sergėjus Rimovskis ◽  
Petr Dostál
Keyword(s):  
Plastic Strain ◽  
Low Cycle Fatigue ◽  
White Layer ◽  
Cyclic Stress ◽  
Cycle Fatigue ◽  
Pure Bending ◽  
Cycle Loading ◽  
Fatigue Characteristics ◽  
Tension Strength ◽  
Hardened Surface

This paper analyses electromechanical hardening of the steel parts surface, when in the contact area so called “white layer” is formed. The experiments were performed to show the influence of “white layer” on strength of the steel C45 specimens under low cycle loading. This paper analyses monotonic and low cycle tension compression and pure bending characteristics of specimens with electromechanically hardened surface. The Performed experiments showed that under monotonic tension strength characteristics (σpr, σ02, σu) are increasing and strain characteristics (eu, ψ) are decreasing. During cyclic stress limited tension compression at low loading levels both the width of plastic strain hysteresis loop and accumulated plastic strain are decreasing, therefore the lifetime is increasing. Under pure bending this tendencies persist, but in this case the lifetime at all loading levels is larger than the lifetime at tension compression.

Low Cycle Fatigue Characteristics of a Ni-Based Single Crystal Superalloy CMSX-4 at Elevated Temperature

2019 ◽  
Vol 36 (3) ◽  
pp. 271-279
Author(s):  
Jae Gu Choi ◽  
Chang-Sung Seok ◽  
Sung Uk Wee ◽  
Eui-Suck Chung ◽  
Byoung-Gwan Yun ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Single Crystal ◽  
Low Cycle Fatigue ◽  
Single Crystal Superalloy ◽  
Cycle Fatigue ◽  
Fatigue Characteristics

scholarly journals Low and high cycle fatigue of heat resistant steels and nickel based alloys in hydrogen for gas, steam turbines and generators applications

2018 ◽  
Vol 165 ◽  
pp. 05002
Author(s):  
Alexander Balitskii ◽  
Jacek Eliasz ◽  
Valentina Balitska
Keyword(s):  
Hydrogen Pressure ◽  
Low Cycle Fatigue ◽  
Cyclic Crack Resistance ◽  
Rotor Steel ◽  
Cycle Fatigue ◽  
Steam Turbines ◽  
Heat Resistant ◽  
Short Term Strength ◽  
Strength And Plasticity ◽  
Heat Resistant Steels

It has been established that, at some region of hydrogen pressure and strain rate exists a maximum influence of hydrogen on the plasticity, low cycle fatigue and cyclic crack resistance of Ni-Co alloys and high nitrogen steels. The drop of plasticity of the dispersion-hardening materials within the temperature range of intense phase transformations is caused by the localization of strains on the grain boundaries due to the intense redistribution of alloying elements in the boundary regions. Moreover, the increase in plasticity observed at higher temperatures is caused both by partial coagulation of hardening phases and possible dissolution of small amounts of finely divided precipitations. The effect hydrogen on short-term strength and plasticity, high- and low-cycle durability of 15Cr12Ni2MoNMoWNb martensitic steel, 10Cr15Ni27Ti3W2BMo austenitic dispersion-hardened steel, heat resistant 3,5NiCrMoV rotor steel, 04Kh16Ni56Nb5Mo5TiAl and 05Kh19Ni55Nb2Mo9Al Ni-base superalloys in range of pressures 0–30 MPa and temperatures 293–1073 K was investigated. In the case of 15Cr12Ni2MoNMoWNb steel and 04Kh16Ni56Nb5Mo5TiAl alloy the dependence of low-cycle durability (N) and characteristics of plasticity (δ and φ) on the hydrogen pressure consists of two regions. In the first region (low pressures), the N, δ and φ abruptly drops, and in the second, the negative action of hydrogen becomes stable or decrease negligibility.

Low-Cycle Strength of Elements of Constructions

2018 ◽  
Author(s):  
Alexander Zvorykin ◽  
Roman Popov ◽  
Mykola Bobyr ◽  
Igor Pioro
Keyword(s):  
Stress State ◽  
Plane Stress ◽  
Low Cycle Fatigue ◽  
Plane Stress State ◽  
Structural Elements ◽  
Cycle Fatigue ◽  
Kinematic Equation ◽  
Effective Coefficients ◽  
Operational Life ◽  
Cycle Loading

Analysis of engineering approach to the operational life forecasting for constructional elements with respect to the low-cycle fatigue is carried out. Applicability limits for a hypothesis on existence of generalized cyclic-deforming diagram in case of complex low-cycle loading (deforming) are shown. It is determined, that under condition of plane-stress state and piecewise-broken trajectories of cycle loading with stresses and deformation checking the cyclic deforming diagram is united in limits of deformations, which are not exceeded 10 values of deformation corresponding material yield point. Generalized kinematic equation of material damageability is described. The method of damageability parameter utilization for increasing of accuracy calculation of structural elements low-cycle fatigue by using the effective coefficients of stresses and deformations taking into account the damageability parameter is given.

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.

Anisotropic Life Prediction for Single Crystal Nickel-Base Flat Plate with a Hole

2014 ◽  
Vol 891-892 ◽  
pp. 1033-1038
Author(s):  
Cheng Li Dong ◽  
Hui Chen Yu ◽  
Ying Li
Keyword(s):  
Single Crystal ◽  
Flat Plate ◽  
Life Prediction ◽  
Failure Strain ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
The Finite Element Method ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Elastoplastic Constitutive Model

The material properties of single crystal (SC) superalloys are orientation-dependent. To fully exploit the material capacity, the life modeling needs to consider the anisotropy. In the present study the life modeling of SC nickel-base superalloys is considered by employing the modified Mücker's anisotropic theory in which a Hill type function is utilized for describing the anisotropic failure. Strain-controlled low cycle fatigue (LCF) experiments of SC nickel-base superalloys at different crystallographic orientations (i.e.[00, [01 and [11) under high temperatures (i.e.760°C) are carried out to verify the modeling availability for the modified Mücker's anisotropic theory. Further, based on the stress-strain field obtained by the anisotropic elastoplastic constitutive model coupled with the finite element method (FEM), the modified Mücker's anisotropic theory is employed to predict the fatigue life for SC flat plate with a hole.

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