A quantitative metallographic assessment of the evolution of porosity during processing and creep in single crystal Ni-base super alloys

Buck, Hinrich; Wollgramm, P.; Parsa, Alireza B.; Eggeler, Gunther

doi:10.1002/mawe.201500379

Cited by 32 publications

(14 citation statements)

References 23 publications

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“…Micropores are locations where creep cracks, which initiate final rupture, can nucleate. [10,11] The subsequent growth of these microcracks leads to creep rupture. The distribution of pores in the microstructure and their arrangement with respect to the dendritic microstructure was shown to be crucial for the onset of tertiary creep.…”

Section: Introductionmentioning

confidence: 99%

“…The distribution of pores in the microstructure and their arrangement with respect to the dendritic microstructure was shown to be crucial for the onset of tertiary creep. [10,11] Micropores form during solidification, heat treatment, and creep. [11] This has recently been studied in a quantitative scanning electron microscope (SEM) investigation, where it was found that cast micropores are most important for creep rupture.…”

Section: Introductionmentioning

confidence: 99%

“…[10,11] Micropores form during solidification, heat treatment, and creep. [11] This has recently been studied in a quantitative scanning electron microscope (SEM) investigation, where it was found that cast micropores are most important for creep rupture. [11] Processing procedures can introduce porosity into engineering materials.…”

Section: Introductionmentioning

confidence: 99%

“…[11] This has recently been studied in a quantitative scanning electron microscope (SEM) investigation, where it was found that cast micropores are most important for creep rupture. [11] Processing procedures can introduce porosity into engineering materials. Therefore, there has always been interest in reducing porosity levels by applying hot isostatic pressing (HIP).…”

Section: Introductionmentioning

confidence: 99%

“…The results are discussed in the light of previous findings. [9][10][11][14][15][16][17][18] 2. Material and Experiments…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The results are discussed in the light of previous findings. [9][10][11][14][15][16][17][18] 2. Material and Experiments…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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Variation of Homogenization Pores during Homogenization for Nickel‐Based Single‐Crystal Superalloys

et al. 2021

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The porosity deteriorates the mechanical properties of nickel‐based superalloys, especially the fatigue properties. Herein, the kinetics model of homogenization porosity growth is optimized. The corresponding diffusion processes during solution heat treatment are simulated by the DICTRA software and verified by experiments. The results show that the homogenization porosity increases first and then decreases during the solution heat treatment, due to the imbalanced diffusion flux between dendritic core (DC) and interdendritic areas (IAs). The diffusion flux first flows toward DC and then toward IAs after fully homogenization of the fast diffusion elements. Moreover, the influence of directional solidification parameters on the homogenization porosity process is investigated. With the increase in the withdraw rate, the dendritic structure is refined, and the S‐porosity decreases. Meanwhile, the dendritic arm spacing decreases; thus, homogenization accelerated increases. In this case, after the solution heat treatment, the homogenization porosity decreases. The results provide two bases to propose a new method to control the homogenization porosity.

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The High Temperature Strength of Single Crystal Ni‐base Superalloys – Re‐visiting Constant Strain Rate, Creep, and Thermomechanical Fatigue Testing

Sirrenberg,

Babinský,

Bürger

et al. 2024

Adv Eng Mater

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The present work takes a new look at the high temperature strength of single crystal (SX) Ni‐base superalloys. It compares high temperature constant strain rate (CSR) testing, creep testing and out‐of‐phase thermomechanical fatigue (OP‐TMF) testing, which represent key characterization methods supporting alloy development and component design in SX material science and technology. The three types of tests are compared using the same SX alloy, working with precisely oriented <001>‐specimens and considering the same temperature range between 1023 and 1223 K, where climb‐controlled micro‐creep processes need to be considered. Nevertheless, the three types of tests provide different types of information. CSR testing at imposed strain rates of 3.3·10‐4 s‐1 shows a yield stress anomaly (YSA) with a YSA stress peak at a temperature of 1073 K. This increase of strength with increasing temperature is not observed during constant load creep testing at much lower deformation rates around 10‐7 s‐1. Creep rates show a usual behavior and increase with increasing temperatures. During OP‐TMF loading, the temperature continuously increases/decreases in the compression/tension part of the mechanical strain‐controlled cycle (±0.5%). At the temperature, where the YSA peak stress temperature is observed, no peculiarities are observed. It is shown that OP‐TMF life is sensitive to surface quality, which is not the case in creep. A smaller number of cycles to failure is observed when reducing the heating rate in the compression/heating part of the mechanical strain‐controlled OP‐TMF cycle. The results are discussed on a microstructural basis, using results from scanning and transmission electron microscopy, and in light of previous work published in the literature.This article is protected by copyright. All rights reserved.

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A quantitative metallographic assessment of the evolution of porosity during processing and creep in single crystal Ni-base super alloys

Cited by 32 publications

References 23 publications

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

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

Variation of Homogenization Pores during Homogenization for Nickel‐Based Single‐Crystal Superalloys

The High Temperature Strength of Single Crystal Ni‐base Superalloys – Re‐visiting Constant Strain Rate, Creep, and Thermomechanical Fatigue Testing

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