Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures

Gustafsson, David; Moverare, Johan; Simonsson, Kjell; Sjöström, Sören

doi:10.1115/1.4002913

Cited by 34 publications

(27 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Polycrystalline IN718 presents a strength well above 1000 MPa, large ductility (>30%), a marked tension-compression strength differential [9], softening under cyclic loading conditions [10] and significant losses of strength above 650°C. These properties are controlled by the microstructural features of the material (grain size, precipitate size and volume fraction, etc.)…”

Section: Introductionmentioning

confidence: 99%

Multiscale modeling of the mechanical behavior of IN718 superalloy based on micropillar compression and computational homogenization

et al. 2015

View full text Add to dashboard Cite

a b s t r a c tA multiscale modeling strategy is presented to determine the effective mechanical properties of polycrystalline Ni-based superalloys. They are obtained by computational homogenization of a representative volume element of the microstructure which was built from the grain size, shape and orientation distributions of the material. The mechanical behavior of each grain was simulated by means of a crystal plasticity model, and the model parameters that dictate the evolution of the critical resolved shear stress in each slip system (including viscoplastic effects as well as self and latent hardening) were obtained from compression tests in micropillars milled from grains of the polycrystal in different orientations suited for single, double (coplanar and non coplanar) and multiple slip. The multiscale model predictions of the compressive strength of wrought IN718 were in good agreement with the experimental results.

show abstract

Section: Introductionmentioning

confidence: 99%

Multiscale modeling of the mechanical behavior of IN718 superalloy based on micropillar compression and computational homogenization

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The strain ranges estimated from Equation 8 and 9 were compared to an elasto-plastic finite element analysis at a few selected load levels using an Armstrong-Frederick type material model calibrated using data from Gustafsson et al [10,11]. The comparison is shown in Figure 4 where it can be seen that Glinka's rule is closer to the finite element results.…”

Section: Calculation Of Strain Rangesmentioning

confidence: 99%

Evaluation of notch effects in low cycle fatigue of alloy 718 using critical distances

et al. 2018

View full text Add to dashboard Cite

Abstract. Gas turbine disks contain many notch-like features acting as stress raisers. The fatigue life based on the notch root stress may be overly conservative as the steep stress gradient in front of the notch may give rise to so-called notch support. In the current work, the theory of critical distances was applied to the prediction of the total fatigue life of low cycle fatigued, notched specimens made from alloy 718. The fatigue tests were performed at 450 °C and 550 °C. It was found that, for lives shorter than 5000-10000 cycles, the notched specimens had longer lives than would have been expected based on the notch root strain. For lives longer than 5000-10000 cycles, there were no notch support. The life prediction for notched specimens could be significantly improved by basing the prediction on the strain chosen some distance from the notch (the critical distance). An expression for calculating the critical distance based on the notch root strain was suggested.

show abstract

“…Components being used in different hazardous environments and other applications usually increase the fatigue rate. A life prediction model for the overload tests microstructuraly investigated by the author in [7] was developed by Gustafsson et al in [31] and for the other test series leading up to it are discussed in [31,[41][42][43][44][45][46][47][48][49][50][51][52] where models for fatigue crack propagation modified to handle e.g. load ratios R, stress-intensity factors K, threshold values and environmental effects, which are vital to accurately enable life prediction.…”

Section: Dcpdmentioning

confidence: 99%

Effect of Dwell-times on Crack Propagation in Superalloys

Saarimäki¹

2015

View full text Add to dashboard Cite

Linköping 2016Front page image: The general crack growth behaviour of Inconel 718 run at 550 ○ C, subjected to a 2160 s dwell-time, with a 15 % overload at the beginning of the dwell-time.During the course of research underlying this thesis, Jonas Saarimäki was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. Printed by LiU-Tryck 2015 © Jonas Saarimäki AbstractGas turbines are widely used in industry for power generation and as a power source at "hard to reach" locations where other possibilities for electrical supply are insufficient. There is a strong need for greener energy, considering the effect that pollution has had on global warming, and we need to come up with ways of producing cleaner electricity. A way to achieve this is by increasing the combustion temperature in gas turbines. This increases the demand on the high temperature performance of the materials used e.g. superalloys in the turbine. These high combustion temperatures can lead to detrimental degradation of critical components. These components are commonly subjected to cyclic loading of different types e.g. combined with dwell-times and overloads at elevated temperatures, which influence the crack growth. Dwell-times have shown to accelerate crack growth and change the cracking behaviour in both Inconel 718 and Haynes 282. Overloads at the beginning of the dwell-time cycle have shown to retard the dwell time effect on crack growth in Inconel 718. To understand these effects more microstructural investigations are needed.The work presented in this licentiate thesis was conducted under the umbrella of the research program Turbo Power; "High temperature fatigue crack propagation in nickel-based superalloys", concentrating on fatigue crack growth mechanisms in superalloys during dwell-times, which have shown to have a devastating effect on the crack propagation behaviour. Mechanical testing was performed under operation-like conditions in order to achieve representative microstructures and material data for the subsequent microstructural work. The microstructures were microscopically investigated in a scanning electron microscope (SEM) using electron channeling contrast imaging (ECCI) as well as using light optical microscopy.The outcome of this work has shown that there is a significant increase in crack growth rate when dwell-times are introduced at the maximum load (0% overload) in the fatigue cycle. With the introduction of a dwell-time there is also a shift from transgranular to intergranular crack growth for both Inconel 718 iii iv and Haynes 282. When an overload is applied prior to the dwell-time, the crack growth rate decreases with increasing overload levels in Inconel 718. At high temperature crack growth in Inconel 718 took place as intergranular crack growth along grain boundaries due to oxidation and the creation of nanometric voids. Another observed growth mechanism was crack advance along δ phase boundaries with subsequent severe oxidation of the δ phase.This thesis comprises two pa...

show abstract

Modeling of the Constitutive Behavior of Inconel 718 at Intermediate Temperatures

Cited by 34 publications

References 13 publications

Multiscale modeling of the mechanical behavior of IN718 superalloy based on micropillar compression and computational homogenization

Multiscale modeling of the mechanical behavior of IN718 superalloy based on micropillar compression and computational homogenization

Evaluation of notch effects in low cycle fatigue of alloy 718 using critical distances

Effect of Dwell-times on Crack Propagation in Superalloys

Contact Info

Product

Resources

About