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Kolbe, M.; Murken, J.; Pistolek, D.; Eggeler, G.; Klam, H.-J.

doi:10.1002/(sici)1521-4052(199908)30:8<465::aid-mawe465>3.3.co;2-c

Cited by 8 publications

(10 citation statements)

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“…There is general interest in small specimen geometries; therefore, we recently developed a miniature creep specimen [6,7,8] in order to investigate the creep strength of thin-walled directionally solidified (DS) turbine blades at temperatures of 1303 K. A detailed description of the sample geometry and the testing procedure has been published elsewhere. [6,7,8] Several creep tests were performed on miniature samples taken from a blade of DS Ni-base superalloy CM247LC.…”

Section: Introductionmentioning

confidence: 99%

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Miniature Specimen Assessment of Creep of the Single-Crystal Superalloy LEK 94 in the 1000 °C Temperature Range

Mälzer

Hayes²,

Mack

et al. 2007

Metall Mater Trans A

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The creep behavior of the Ni-base superalloy LEK 94 in the 1000°C range has been investigated. Miniature tensile specimens were employed, which can be taken out of a thin walled blade or used when only limited amounts of material are available. We show that this miniature test technique yields reasonable creep data, including stress exponents n and apparent activation energies Q app . The n values are close to 5 and the Q app values are close to 500 kJ/mole, independent of the crystallographic direction. Creep rates are fastest for samples oriented in the [110] direction, followed by [001] samples. The lowest creep rates are observed for the [111] direction. This difference is related to a difference in resolved shear stresses and in the number of activated crystallographic slip systems. As a striking new result, it was observed that the onset of tertiary creep occurs earlier and rupture strains are significantly smaller in the case of [110] specimens as compared to [100] specimens, while the [111] specimens show an intermediate behavior. These effects are related to the alignment of cast porosity along the axis of primary dendrites. When cast micropores align perpendicular to the axis of the applied tensile stress, the onset of fast tertiary creep occurs early and small rupture strains are observed.

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Section: Introductionmentioning

confidence: 99%

“…[6,7,8] Several creep tests were performed on miniature samples taken from a blade of DS Ni-base superalloy CM247LC. The creep curves obtained in References 6 through 8 look reasonable, but no validation by comparison to standard creep specimens was performed.…”

Section: Introductionmentioning

confidence: 99%

Miniature Specimen Assessment of Creep of the Single-Crystal Superalloy LEK 94 in the 1000 °C Temperature Range

Mälzer

Hayes²,

Mack

et al. 2007

Metall Mater Trans A

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“…[19] All details concerning creep testing have been reported elsewhere. [10,[19][20][21] Uniaxial <100> tensile creep tests were performed in two temperature/stress regimes, 1 050 C/160 MPa and 750 C/800 MPa. Creep tests were performed using specimens with microstructures which formed with and without HIP treatment.…”

Section: Hot Isostatic Pressing and Creep Testingmentioning

confidence: 99%

On the Effect of Hot Isostatic Pressing on the Creep Life of a Single Crystal Superalloys

et al. 2016

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The creep behavior of a single-crystal Ni-base superalloy in two microstructural states is compared. One is obtained by casting followed by a conventional heat treatment. The other results from the same nominal heat treatment integrated into a hot isostatic pressing process. The microstructure after HIP differed from that in the conventional route in two respects. First, the g 0 particles are smaller and the g channels are narrower. Second, after HIP, the number density of pores is lower and the pore sizes are smaller. The HIP microstructure improves creep in two respects: the finer g/g 0 -microstructure results in lower minimum creep rates. Moreover, the shrinkage of cast porosity during HIP delays the nucleation and growth of micro cracks and results in higher rupture strains in the low-temperature high stress regime.

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“…Besides the shell temperature, the cast temperature and thickness of insulation layer show an impact on the SDAS, especially for great wall thicknesses (steps 1-3). On the contrary, the variation of the wall thickness d step affects the SDAS in thin areas (steps [3][4][5]. The correlation between heat transfer coefficient (between insulation and ambient) and SDAS needs to be neglected, since an input data correlation of 0.4 was assumed between T shell and a amb .…”

Section: Probabilistic Analysismentioning

confidence: 99%

“…If only a small amount of material is available or the material is very costly, as in the case of nickel-base superalloys, small-scale specimens have a great advantage. Furthermore, the scaled specimens offer the possibility to take samples from components, like thin walled turbine blades [5] or welded steam pipes, [6] for material investigations. For this reason, the present paper investigates the influence of specimen geometry on the mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Sensitivity Analysis for the Determination of Casting Parameter–Microstructure–Property Relations and Mechanical Properties of IN738LC in Investment Casting

et al. 2014

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The development of manufacturing processes for high-performance investment casting components in turbomachinery is an iterative process, which takes a lot of development time for engineers and foundry occupation. The reduction of these expensive preliminary tests is possible by combining probabilistic methods with modern simulation tools for the numerical description of the casting and solidification processes. Starting from the deterministic simulation of the casting process, the casting and solidification parameters including their production tolerances are taken into account in the probabilistic simulation. Through a multi-dimensional statistical analysis of the numerous parameters of the casting process and the achieved virtual casting results, the correlations between the process parameters and component quality can be worked out. Furthermore, a design of experiment (DoE) was performed with real castings to confirm the influence of the main parameters on the result quantities. Mechanical and microstructural characterizations of appropriate cast specimens allow a validation of the simulation results and the formulation of casting parametermicrostructure-property relations. The mechanical properties are studied by uniaxial hot tensile tests using standard and small-scale specimens. Furthermore, the uniaxial fatigue behavior and the life times at elevated temperatures are investigated.

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Cited by 8 publications

References 0 publications

Miniature Specimen Assessment of Creep of the Single-Crystal Superalloy LEK 94 in the 1000 °C Temperature Range

Miniature Specimen Assessment of Creep of the Single-Crystal Superalloy LEK 94 in the 1000 °C Temperature Range

On the Effect of Hot Isostatic Pressing on the Creep Life of a Single Crystal Superalloys

Numerical and Experimental Sensitivity Analysis for the Determination of Casting Parameter–Microstructure–Property Relations and Mechanical Properties of IN738LC in Investment Casting

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