Life prediction of l6 steel using strain-life curve and cyclic stress-strain curve by means of low cycle fatigue testing

The present work is focused on the study of microstructure and low cycle fatigue behavior of the first generation nickel-base superalloy IN 713LC (low carbon) and its promising second generation successor MAR-M247 HIP (hot isostatic pressing) at 900 °C. Microstructure of both alloys was studied by means of scanning electron microscopy (SEM). The microstructure of both materials is characterized by dendritic grains, carbides and casting defects. Size and morphology of precipitates and casting defects were evaluated. Fractographic observations have been made with the aim to reveal the fatigue crack initiation place and relation to the casting defects and material microstructure. Low cycle fatigue tests were conducted on cylindrical specimens in symmetrical push-pull cycle under strain control with constant total strain amplitude and strain rate at 900 °C in air. Hardening/softening curves, cyclic stress-strain curve and fatigue life data of both materials were obtained. Cyclic stress-strain curve of MAR M247 is shifted approximately to 120 MPa higher stress amplitudes in comparison with IN 713LC. Significantly higher fatigue life of MAR-M247 has been observed in Basquin representation. On the other hand IN 713LC shows prolonged lifetime compared with MAR-M247 in the Coffin-Manson representation. Results obtained from high temperature low cycle fatigue tests are discussed.

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Cyclic Plastic Deformation of a Circular Plate With Work Hardening

Journal of Pressure Vessel Technology ◽

10.1115/1.3264361 ◽

1984 ◽

Vol 106 (4) ◽

pp. 336-341

Author(s):

R. Winter

Keyword(s):

Fatigue Life ◽

Low Cycle Fatigue ◽

Nonlinear Behavior ◽

Strain Curve ◽

Strain Range ◽

Cyclic Strain ◽

Cyclic Stress ◽

Cycle Fatigue ◽

Stress Strain ◽

Element Analysis

An experimental and theoretical study was performed of the nonlinear behavior of a simply supported flat circular aluminum plate under reversed cyclic central load. The application is for the analysis of cyclic stress and strain of structural components in the plastic range for predicting low-cycle fatigue life. The main purpose was to determine the relative accuracy of an elastic-plastic large deformation finite element analysis when the material properties input data are derived from monotonic (noncyclic) stress-strain curves versus that derived from cyclic stress-strain curves. The results showed that large errors could be induced in the theoretical prediction of cyclic strain range when using the monotonic stress-strain curve, which could lead to large errors in predicting low-cycle fatigue life. The use of cyclic stress-strain curves, according to the model developed by Morrow, et al., proved to be accurate and convenient.

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Cyclic Stress-Strain Behavior and Low-Cycle Fatigue of Ti 6-4 at 260°C

Journal of Engineering Materials and Technology ◽

10.1115/1.2904190 ◽

1992 ◽

Vol 114 (4) ◽

pp. 390-398 ◽

Cited By ~ 2

Author(s):

T. Bui-Quoc ◽

R. Gomuc ◽

A. Biron

Keyword(s):

Strain Amplitude ◽

Low Cycle Fatigue ◽

Strain Curve ◽

Cyclic Stress ◽

Fatigue Tests ◽

Cycle Fatigue ◽

Stress Strain ◽

Strain Behavior ◽

Show Evidence ◽

Strain Cycling

Low-cycle fatigue tests on Ti 6-4 (Ti-6Al-4V) have been carried out at 260°C under strain-controlled conditions with constant strain amplitude and increasing multistep strain levels. The results of constant strain amplitude tests were used to establish the fatigue diagram whereas the multistep tests were examined to assess the cyclic stress-strain behavior in comparison with the conventional stress-strain curve. Most of the tests were carried out under zero-to-tension conditions in the intermediatecycle range (Nf ≃ 3 x 103 to 105 cycles). The effect of prior strain cycling on the tensile properties was also investigated. The experimental data is discussed together with theoretical evaluations. In addition, microstructural examinations of the rupture surfaces have been made to show evidence on the type of crack initiation sites and on the crack propagation modes at different strain levels.

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A multiaxial stress-strain analysis for proportional cyclic loading

The Journal of Strain Analysis for Engineering Design ◽

10.1243/03093247v282125 ◽

1993 ◽

Vol 28 (2) ◽

pp. 125-133 ◽

Cited By ~ 4

Author(s):

A Navarro ◽

M W Brown ◽

K J Miller

Keyword(s):

Strain Analysis ◽

Hysteresis Loops ◽

Strain Curve ◽

Cyclic Stress ◽

Strain Hardening Exponent ◽

Stress Strain Curve ◽

Stress Strain ◽

Flow Equations ◽

Deformation Response ◽

Tubular Specimens

A simplified treatment is presented for the analysis of tubular specimens subject to in-phase tension-torsion loads in the elasto-plastic regime. Use is made of a hardening function readily obtainable from the uniaxial cyclic stress-strain curve and hysteresis loops. Expressions are given for incremental as well as deformation theories of plasticity. The reversals of loading are modelled by referring the flow equations to the point of reversal and calculating distances from the point of reversal using a yield critertion. The method has been used to predict the deformation response of in-phase tests on an En15R steel, and comparisons with experimental data are provided. The material exhibited a non-Masing type behaviour. A power law rule is developed for predicting multiaxial cyclic response from uniaxial data by incorporating a hysteretic strain hardening exponent.

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