Issues in Processing by the Liquid-Sn Assisted Directional Solidification Technique

Elliott, Andrew; Karney, G.B.; Gigliotti, M. F. X.; Pollock, Tresa M.

doi:10.7449/2004/superalloys_2004_421_430

Cited by 19 publications

(19 citation statements)

References 18 publications

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“…The processes to do this include the use of a cooling media below the casting furnace to increase thermal gradients such as gas cooling [32], fluidized-bed [33], and liquid-metal [34]. What appears to be the major advantage is a reduction in freckle and misaligned grains, which should reduce barriers to bucket geometry and increase casting yields [35,36].…”

Section: Futurementioning

confidence: 99%

Optimizing SC Ren� N4 Alloy for DS Aft-Stage Bucket Applications in Industrial Gas Turbines

Bouse¹,

Schaeffer²,

Henry³

2008

Superalloys 2008 (Eleventh International Symposium)

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Single crystal (SC) René N4 aircraft engine turbine blade superalloy was converted to a directionally solidified (DS) alloy for latter-stage industrial gas turbine (IGT) buckets. The new alloy, called GTD444™, is being used in GE's steam cooled MS7001H (7H) for 3 rd and 4 th stage turbine buckets, and in conventionally cooled MS7001FB (7FB) and MS9001FB (9FB) IGT's for 2 nd & 3rd stage turbine buckets. The alloy was created primarily by the addition of Boron (B) to SC René N4, and the change to a heat treatment that includes a final hold at ~2280°F (1249°C) for full γ' solutioning. The investment casting processing included a major scale-up effort (from GE Aviation SC-size) up to ~36 inch (91 cm) long buckets, with a weight up to ~40 pounds (18 kg) each. The emphasis of the paper is on casting and alloy development, material characterization, and optimization of mechanical properties. The amount of B was optimized for casting yield (including the influence of solutioning temperature, grain boundary cracking and recrystallized grains), and longitudinal and transverse creep strength. As of 1/31/08, GTD444 alloy in the advanced machine fleet leader has passed 8,000 fired hours, which is considered an industry milestone.

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Section: Futurementioning

confidence: 99%

Optimizing SC Ren� N4 Alloy for DS Aft-Stage Bucket Applications in Industrial Gas Turbines

Bouse¹,

Schaeffer²,

Henry³

2008

Superalloys 2008 (Eleventh International Symposium)

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“…A lower or higher rate will cause abnormal columnar grains, which coincides with that of Elliot et al [22]. In the real production in aeronautical industry, it is necessary to adopt a higher withdrawal rate to improve the productivity.…”

Section: Comparison Of Simulation Results With Experimentalmentioning

confidence: 54%

Numerical simulation of microstructure evolution during directional solidification process in directional solidified (DS) turbine blades

Hang

Tang

et al. 2011

Sci. China Technol. Sci.

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Directional solidified (DS) turbine blades are widely used in advanced gas turbine engine. The size and orientation of columnar grains have great influence on the high temperature property and performance of the turbine blade. Numerical simulation of the directional solidification process is an effective way to investigate the grain's growth and morphology, and hence to optimize the process. In this paper, a mathematical model was presented to study the directional solidified microstructures at different withdrawal rates. Ray-tracing method was applied to calculate the temperature variation of the blade. By using a Modified Cellular Automation (MCA) method and a simple linear interpolation method, the mushy zone and the microstructure evolution were studied in detail. Experimental validations were carried out at different withdrawal rates. The calculated cooling curves and microstructure agreed well with those experimental. It is indicated that the withdrawal rate affects the temperature distribution and growth rate of the grain directly, which determines the final size and morphology of the columnar grain. A moderate withdrawal rate can lead to high quality DS turbine blades for industrial application. directional solidified (DS) turbine blade, Cellular Automation (CA), numerical modeling and simulation Citation: Zhang H, Xu Q Y, Tang N, et al. Numerical simulation of microstructure evolution during directional solidification process in directional solidified (DS) turbine blades.

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“…(4) and (5), measured by Elliott et al [5] using molds instrumented with thermocouples for verification of experimental thermal gradient. The data were generated using a set of similar withdrawal rate experiments performed in the University of Michigan's Bridgman furnace with and without liquid-Sn assisted cooling [38]. The largest deviations from Eq.…”

Section: Primary and Secondary Dendritesmentioning

confidence: 99%

Characterization of Three-Dimensional Dendritic Structures in Nickel-Base Single Crystals for Investigation of Defect Formation

Madison¹,

Spowart²,

Rowenhorst³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

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During solidification, solute-induced convective instabilities at the solid -liquid interface can result in the formation of defects such as freckles and misoriented grains in superalloy single crystals. These defects can be particularly detrimental to the properties of single crystal nickel-base superalloys. Unfortunately, detailed understanding of fluid flow at the scale of the dendritic structure has yet to be fully understood, particularly under conditions in which heat extraction is non-axial. The objective of this research is to develop a technique for quantifying the dendritic structure and morphology at the solid -liquid interface for the purpose of providing direct input into computational fluid flow modeling. Using the RoboMET.3D serial sectioning system, threedimensional datasets of dendritic structure at the solidification front have been obtained for René N4 abruptly decanted during solidification. Distribution and arrangement of solid and liquid in the vicinity of dendrite tips is analyzed and the implications for defect formation are discussed.

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Issues in Processing by the Liquid-Sn Assisted Directional Solidification Technique

Cited by 19 publications

References 18 publications

Optimizing SC Ren� N4 Alloy for DS Aft-Stage Bucket Applications in Industrial Gas Turbines

Optimizing SC Ren� N4 Alloy for DS Aft-Stage Bucket Applications in Industrial Gas Turbines

Numerical simulation of microstructure evolution during directional solidification process in directional solidified (DS) turbine blades

Characterization of Three-Dimensional Dendritic Structures in Nickel-Base Single Crystals for Investigation of Defect Formation

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