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The Growth-Path Method for Prediction of Spurious Grain Nucleation in Single-Crystal Castings

Published

Author(s)

R E. Napolitano, A R. Roosen, Robert J. Schaefer

Abstract

Prediction of spurious grain formation in superalloy castings is critical for the design and development of single-crystal gas-turbine components. Here, we describe the growth-path method for assessing the tendency for spurious grain formation in such castings. In this method, temperature data from previously performed thermal simulation is utilized for tracking the growth of the dendritic front along a specified path through the casting, taking into consideration the dendrite tip kinetics and the crystallographic orientation. This procedure provides the temperature and liquid-fraction vs. Time profile for any point on the specified path. The nucleation probability, corrected for the liquid-fraction, is then integrated along the cooling path to provide a quantitative nucleation potential. The method is demonstrated for a simple mold corner using three different sets of paths, illustrating that the method requires specification of the minimum-time path to any given point. Plots of front shape, undercooling, and nucleation potential are generated. The effect of secondary orientation is also demonstrated.
Conference Dates
July 12-16, 1998
Conference Location
Undefined
Conference Title
Pacific Rim International Conference On Advanced Materials and Processing

Keywords

single-crystal castings, spurious grains, stray grains, superalloys

Citation

Napolitano, R. , Roosen, A. and Schaefer, R. (2008), The Growth-Path Method for Prediction of Spurious Grain Nucleation in Single-Crystal Castings, Pacific Rim International Conference On Advanced Materials and Processing, Undefined (Accessed May 22, 2024)

Issues

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Created October 16, 2008