Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop

Storgärds, Erik; Simonsson, Kjell

doi:10.1007/s11340-014-9963-2

Cited by 15 publications

(20 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The area ahead of the crack tip immediately following the hold however shows areas of intergranular as well as transgranular crack propagation. This agrees with the work of Storgärds et al [21]. Additionally, secondary cracking was observed extending parallel to the crack growth direction.…”

Section: Taz Fractographysupporting

confidence: 93%

Predictive Modeling of Arbitrary Loaded TMF Crack Growth in Superalloys

Johnson

Neu

Radzicki³

et al. 2018

MATEC Web Conf.

View full text Add to dashboard Cite

Abstract. Hot sections in turbine engines are subjected to large variations in temperatures and mechanical/thermal loadings. As such, accurate predictions of fatigue crack growth must account for many physical phenomena: temperature dependent crack growth behavior, load interaction history effects, time at temperature effects, temperature history effects, and the effects of stress/temperature/time on the materials. Through extensive experimental work on superalloys, a very definite "temperature history effect" on the resulting crack growth behavior has been identified and modeled. This work also identified a Temperature Affected Zone (TAZ) that occurs ahead of the crack tip and affects subsequent crack growth rates. The size of the TAZ is dependent on temperature, hold time, and stress state. Measurements of the TAZ were made under various conditions. The changes that occur in this TAZ are a combination of oxidation and material microstructure evolution. Various simplified "hot section" engine spectra (changing temperatures and stress levels) were tested to determine resulting crack growth behavior. Correlation between the experiments and model predictions were good and generally conservative.

show abstract

Section: Taz Fractographysupporting

confidence: 93%

Predictive Modeling of Arbitrary Loaded TMF Crack Growth in Superalloys

Johnson

Neu

Radzicki³

et al. 2018

MATEC Web Conf.

View full text Add to dashboard Cite

show abstract

“…More details about the damaged zone concept and experimental findings including fracture surface investigations regarding the same can be found in e.g. [25]. …”

Section: Resultsmentioning

confidence: 99%

“…The latter was based on temperature induced beach marks for cyclic load of 0.5 Hz, for which measurements of crack length and PD values were correlated with each other. For additional description about the experiments see also [3,25].…”

Section: Methodsmentioning

confidence: 99%

Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading

Storgärds

Simonsson

Sjöström

2016

Theoretical and Applied Fracture Mechanics

View full text Add to dashboard Cite

a b s t r a c tHigh temperature materials subjected to elevated temperature have been shown to be sensitive to dwell times, giving an increased crack growth rate. The interaction between these dwell times and rapid cyclic loads have been shown to constitute a complex problem. Many models have been developed for 1D conditions, but the application to general 3D conditions has seldom been seen, although this is the most common case in most structures. In this paper a model for taking care of the interaction between these load modes in general 3D crack growth has been developed. The model uses 1D results for extension to general 3D, thus providing for local crack front evolution with a minimum of numerical simulations. Consequently, a history dependent crack growth law in 3D is given in this paper, which is capable of tracking the damage from the sustained load, and the interaction with rapid cyclic loading. The model has been implemented for usage with finite element calculations and several different tests are simulated and compared with experimental results for the nickel based superalloy Inconel 718 at 550°C. The simulation results show crack shapes in agreement with experimental fracture surfaces and time to failure.

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

Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop

Cited by 15 publications

References 18 publications

Predictive Modeling of Arbitrary Loaded TMF Crack Growth in Superalloys

Predictive Modeling of Arbitrary Loaded TMF Crack Growth in Superalloys

Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading

Effect of Dwell-times on Crack Propagation in Superalloys

Contact Info

Product

Resources

About