Methodology of quantitative evaluation of porosity, dendrite arm spacing and grain size in directionally solidified blades made of CMSX-6 nickel alloy

Roskosz, S.; Adamiec, Janusz

doi:10.1016/j.matchar.2009.01.024

Cited by 23 publications

(10 citation statements)

References 9 publications

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“…However, secondary dendrite arm depend on both the multiplication of both withdrawal rate and thermal gradient which results in cooling rate. Therefore, calculation of SDAS could would be useful in measurement of cooling rate and subsequently, determination of casting defects .…”

Section: Resultsmentioning

confidence: 99%

Effect of withdrawal rate transition on microstructural features of a single crystal Ni‐based superalloy

Sadeghi

Kermanpur

Heydari

et al. 2017

Crystal Research and Technology

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The effect of withdrawal rate transition during Bridgman directional solidification on microstructural aspects of a single crystal Ni-based superalloy was investigated under both constant and changing withdrawal regimes. Variations of primary and secondary dendrite arm spacing (PDAS and SDAS, respectively) and crystal orientation were investigated using optical microscopy and electron backscattered diffraction (EBSD) techniques. The results showed a gradual decreasing trend in PDAS and SDAS by sudden increasing of withdrawal rate. Changes on PDAS was quantified as history-dependent such that for a given secondary withdrawal rate, a higher PDAS was found for a lower initial withdrawal rate. The withdrawal rate transition showed a direct influence on crystal orientation.

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Section: Resultsmentioning

confidence: 99%

Effect of withdrawal rate transition on microstructural features of a single crystal Ni‐based superalloy

Sadeghi

Kermanpur

Heydari

et al. 2017

Crystal Research and Technology

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“…For microstructural characterization, the samples were sectioned from the mid-airfoil areas, perpendicular to the blade axis. The samples were prepared according to procedure described earlier [9][10][11]. After ultrasonic cleaning, electrochemical etching in 10% oxalic acid solution (voltage: 6V, time: 5s) was applied.…”

Section: Methodsmentioning

confidence: 99%

“…For EBSD analysis, samples were additionally polished using an alumina suspension (grit size: 0.05 µm) for 5 h with vibration. The determination of internal porosity was carried out on polished samples by image analysis based on optical micrographs (using an Olympus GX-70 light microscope) in accordance with procedures described in literature [9][10][11].…”

Section: Methodsmentioning

confidence: 99%

Characterizing the Effects of Hot Isostatic Pressing on IN713C Superalloy Blade Microstructure by Electron Backscatter Diffraction

2016

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The integrity of turbine blades is essential for the safe operation of jet engines. Thus, the mechanical properties, especially creep resistance and fatigue strength at high temperatures, must be thoroughly optimized. In particular, it has previously been observed that the mechanical properties of blades depend on the microstructure and porosity resulting from the casting process. To decrease the internal porosity generated by investment casting, hot isostatic pressing can be applied. This paper aims to evaluate the effects of hot isostatic pressing on the microstructure of IN713C alloy blades. Two variants of hot isostatic pressing treatment, differing in pressure, were carried out, and each resulted in lowered porosity. Microstructural investigations, performed using scanning electron microscopy and electron backscatter diffraction revealed significant changes of γ particles and high strain intensity in the surface layer of the blades after hot isostatic pressing treatment.

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“…Samples 1 and 4 were also cut in two other sections, S2 and S3, as shown in Fig. 1c for metallographic observations using BUEHLER expert system procedures described in Roskosz and Adamiec (2009). OM (optical microscopy) and SEM (scanning electron microscopy) microcopies were used to characterize the as-cast microstructures.…”

Section: Methodsmentioning

confidence: 99%

Hot tearing in polycrystalline Ni-based IN738LC superalloy: Influence of Zr content

Heydari

Fard

Bakhshi

et al. 2014

Journal of Materials Processing Technology

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a b s t r a c tZirconium is always present in Ni base superalloys as it enhances their creep properties. In the present study, the influence of very small Zr additions, 100-400 ppm, i.e. 0.01-0.04 wt.%, on hot tearing of IN738LC superalloy is experimentally investigated using dedicated turbine blade castings. Although the Zr content remains very small, it has a strong effect on hot tearing tendency. Microstructure of hot tear in as-cast samples reveal that grain size and secondary dendrite arm spacing have no significant effect on hot tearing. On the other hand eutectic phase volume fraction and its dispersion or spreading along grain boundaries drastically affect the hot tearing propensity and strongly increase with increasing amounts of Zr. Hence grain coalescence becomes impossible at grain boundaries covered with eutectic phase films. With increasing Zr content, gain coalescence between two distinct grains with no interdendritic phase requires more undercooling. Coalescence is retarded and occurs deeper in the mush zone, i.e. at lower temperatures resulting in a higher sensitivity to hot tearing. Finally, it is shown that a reduction of Zr content to 0.02 wt.% is required to fully suppress hot tearing in polycrystalline IN738LC blades.

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Methodology of quantitative evaluation of porosity, dendrite arm spacing and grain size in directionally solidified blades made of CMSX-6 nickel alloy

Cited by 23 publications

References 9 publications

Effect of withdrawal rate transition on microstructural features of a single crystal Ni‐based superalloy

Effect of withdrawal rate transition on microstructural features of a single crystal Ni‐based superalloy

Characterizing the Effects of Hot Isostatic Pressing on IN713C Superalloy Blade Microstructure by Electron Backscatter Diffraction

Hot tearing in polycrystalline Ni-based IN738LC superalloy: Influence of Zr content

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