Effect of Composition and Microstructure on the Low Cycle Fatigue Strength of Structural Steels

1965 ◽  
Vol 87 (2) ◽  
pp. 269-274 ◽  
Author(s):  
R. D. Stout ◽  
A. W. Pense
Keyword(s):  
Low Cycle Fatigue ◽  
Strain Range ◽  
Structural Steels ◽  
Cycle Life ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Fatigue Data ◽  
Number Of Cycles ◽  
Relationship Of ◽  
Cycles To Failure

In a number of studies of data obtained from fatigue tests on various materials it has been shown that the number of cycles to failure is related to the strain range by a relationship of the form εNm=c where N is the number of cycles to failure, ε the strain range, and m and c are constants. In the low cycle portion of the strain range versus cycles to failure curve, evidence has been presented by several investigators to show that the relationship should be εpN1/2=c where εp is the plastic strain range and c, the constant, can be related to tensile ductility. Some investigators have found the relation εtNm=c more useful. Here εt is the total strain range. As a result of a series of Pressure Vessel Research Committee investigations at Lehigh University, a large body of low cycle fatigue data has been obtained for a wide range of steels, microstructures, heat-treatments, and testing conditions. A study of these data has been undertaken, with special emphasis on the suitability of a relationship of this type for analysis and representation of fatigue data. As a result of this study the following conclusions have been drawn: (a) In the range of 5000 to 100,000 cycles a relation εtNm = c appears to be satisfactory. (b) Using this latter relation, an analysis of the low cycle fatigue behavior of structural steels reveals that they can be classified into three broad groups on the basis of their composition. Each group has a characteristic value of m and c which can be used to predict their behavior over the range 5000–100,000 cycles. (c) The value of m and the total strain for 5000 cycle life can be related to n, the strain hardening exponent, for the steels. The total strain for 100,000 cycle life is related to the ultimate tensile strength of the steels. Using these relationships, the fatigue curve for a structural steel can be estimated from tension test data. (d) The effect of microstructural variations for a steel within any one of the three groups was of secondary importance when compared to the compositional groupings, although some systematic effects of microstructural variations were noted.

Modeling and Numerical Simulation of the Effect of Temperature on the LCF Behaviour of a CuCrZr Alloy Specimen

2020 ◽  
Vol 50 ◽  
pp. 37-47
Author(s):  
M. Benhaddou ◽  
M. Ghammouri ◽  
Z. Hammouch ◽  
F. Latrache
Keyword(s):  
Test Piece ◽  
Low Cycle Fatigue ◽  
Effect Of Temperature ◽  
Cycle Fatigue ◽  
Alloy Specimen ◽  
Number Of Cycles ◽  
Increasing Temperature ◽  
Relationship Of ◽  
The Relationship ◽  
Cylindrical Test

The main originality of this work consists in investigating low cycle fatigue of cylindrical test piece with wings under imposed constraint and for the temperature 20°c, 200°c, 400°c. Based on a combination between the fatigue parameter of Jiang-Sehitoglu and the relationship of Coffin-Manson, a numerical model for the prediction of the number of cycles at break. It was found that the CuCrZr cylindrical test piece showed a reduction in fatigue life with increasing temperature.

Microstructure Evolution during LCF of a 10%Cr Steel at Room Temperature

2016 ◽  
Vol 879 ◽  
pp. 1311-1316 ◽  
Author(s):  
Roman Mishnev ◽  
Nadezhda Dudova ◽  
Rustam Kaibyshev
Keyword(s):  
Cyclic Loading ◽  
Dislocation Density ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Strain Softening ◽  
Low Cycle Fatigue ◽  
Lattice Dislocation ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Number Of Cycles

The influence of cyclic loading on microstructure and hardness of a 10%Cr steel with 3%Co and 0.008%B was examined at room temperature and total strain amplitudes of ±0.25% and ±0.6%. Low cycle fatigue (LCF) curves exhibit a stress peak after a few cycles. Hardening is attributed to an increase in dislocation density; no changes in lath size were observed. Then stress tends to decrease monotonically with number of cycles that is indicative for material softening. At εac =±0.25%, strain softening is attributed to decreasing dislocation density and lath coarsening under LCF, whereas at εac =±0.6%, the knitting reaction between dislocations comprising lath boundaries and trapped lattice dislocation leading to the transformation of lath boundaries to subboundaries is a reason for hardness decrease and strain-induced subgrain coarsening.

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.

An Experimental Study on Low Cycle Fatigue of Inconel 617 Super Alloy

2006 ◽  
Vol 306-308 ◽  
pp. 163-168 ◽  
Author(s):  
Jae Hoon Kim ◽  
Duck Hoi Kim ◽  
Young Shin Lee ◽  
Young Jin Choi ◽  
Hyun Soo Kim ◽  
...  
Keyword(s):  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
Cycle Fatigue ◽  
Inconel 617 ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Super Alloy

Low cycle fatigue tests are performed on the Inconel 617 super alloy that be used for structural material of hot gas casing for gas turbine. The relations between strain energy density and number of cycles to failure are examined in order to predict the low cycle fatigue life of Inconel 617 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. And, the cyclic behavior of the Inconel 617 super alloy is characterized by cyclic hardening with increasing number of cycles.

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).

A General Criterion for Low-Cycle Multiaxial Fatigue Failure

1989 ◽  
Vol 111 (3) ◽  
pp. 263-269 ◽  
Author(s):  
A. Makinde ◽  
K. W. Neale
Keyword(s):  
Shear Strain ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Multiaxial Fatigue ◽  
General Criterion ◽  
Cycle Fatigue ◽  
Maximum Shear Strain ◽  
Number Of Cycles ◽  
New Criterion ◽  
Cycles To Failure

A new, general criterion is proposed for multiaxial low-cycle fatigue failure. Contours of constant fatigue life on a plot of maximum shear strain against the tensile strain acting normal to the plane of maximum shear strain are represented by a parametric criterion of the form g(θ,Nf)=kf1(θ)f2(Nf). Here g is the magnitude of the vector from the origin to a point on the constant life contour, θ is the angle associated with g in this space, Nf is the number of cycles to failure, k is a constant and f1 (θ) and f2(Nf) are two separate functions of θ and Nf, respectively. It is shown that all previously proposed macroscopic criteria are particular cases of the failure function g(θ, Nf). Experimental results from several authors are analyzed using the new criterion.

HIGH TEMPERATURE LOW CYCLE FATIGUE AND FRACTURE CHARACTERISTIC IN TWO SINGLE CRYSTAL SUPERALLOYS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2892-2897
Author(s):  
J. J. YU ◽  
Z. H. WANG ◽  
X. F. SUN ◽  
T. JIN ◽  
H. R. GUAN ◽  
...  
Keyword(s):  
Stress Amplitude ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Total Strain ◽  
Stress Axis ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Refractory Elements ◽  
Fatigue And Fracture

Total strain controlled low cycle fatigue tests were conducted at 1173K for DD32 and SRR99 alloys. With the increase of total strain range, the stress amplitude of DD32 alloy improved more fleetly than that of SRR99 alloy. At total strain ranges less than or equal to 1.0%, the low cycle fatigue life of DD32 alloy was greater than that of SRR99 alloy. It was shown that the higher content of refractory elements in DD32 alloy resulted in a remarkable improvement of LCF properties compared to SRR99 alloy. The crack propagation perpendicular to the stress axis occurred in transgranular mode in both alloys. DD32 alloy presented more ductile character than SRR99 alloy.

Low Cycle Fatigue Behavior of Alloy 800H Base Metal and Weldments at 700°C

2018 ◽  
Author(s):  
Seon-Jin Kim ◽  
Rando Tungga Dewa ◽  
Woo-Gon Kim ◽  
Eung-Seon Kim
Keyword(s):  
Base Metal ◽  
Deformation Behavior ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Fatigue Tests ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Alloy 800H ◽  
Total Strain Range

Alloy 800H is currently being considered as one of the near-term candidate materials for design and construction of some major high temperature components of a very high temperature reactor (VHTR). System start-ups and shut-downs as well as power transients will produce low-cycle fatigue loadings of components. The aim of this work is to study the low cycle fatigue behavior of Alloy 800H base metal and weldments at 700°C. The weldment specimens were machined from gas tungsten arc welding (GTAW) butt-welded plate such that the loading direction was oriented transverse to the welding direction. Fully reversed total-strain controlled low-cycle fatigue tests have been performed at total strain ranges of 0.6, 0.9, 1.2 and 1.5%. For all the low-cycle fatigue tests, triangular test waveforms with a constant strain rate of 10−3/s were applied. Low-cycle fatigue testing was conducted in accordance with ASTM Standard E606 on servo-hydraulic test machines. And also, creep-fatigue experiments were carried out at 700°C employing 0.6% total strain range and 10−3/s strain rate using trapezoidal waveform with tension hold time. The main focus is to characterize the low-cycle fatigue properties for Alloy 800H weldment specimens from the cyclic deformation behavior and fatigue fracture behavior. The cyclic deformation behavior was influenced by total strain range and material property. The fatigue life was decreased with increasing the total strain range for both base metal and weldment. However, the lives of weldment specimens have a longer life than that of base metal at lower total strain ranges. It was also observed that creep effects play a significant role in fatigue life reduction.

Low-Cycle Fatigue of Two Nickel-Base Alloys by Thermal-Stress Cycling

1960 ◽  
Vol 82 (3) ◽  
pp. 661-670 ◽  
Author(s):  
F. J. Mehringer ◽  
R. P. Felgar
Keyword(s):  
Thermal Stress ◽  
Thermal Stresses ◽  
Low Cycle Fatigue ◽  
Plastic Strains ◽  
Cycle Fatigue ◽  
Cyclic Life ◽  
Stress Cycling ◽  
Nickel Base ◽  
Number Of Cycles ◽  
Cycles To Failure

Cast DCM and cast Udimet 500, two nickel-base alloys, were tested in a thermal-stress-cycling device of the Coffin type. The strains induced by the thermal stresses were analyzed in several ways in an attempt to relate the plastic strains to cyclic life. The plastic strains were too small to permit calculating them with sufficient accuracy to correlate with cyclic life. It was found, however, that stress range did correlate reasonably well with the number of cycles to failure.

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