J. M. Vitek, S. A. David, Oak Ridge National Laboratory, Oak Ridge, TN; S. S. Babu, Ohio State University, Columbus, OH

Summary: Work was carried out to investigate the mechanism of stray grain formation in nickel-based single crystal superalloys. Once the mechanism for stray grain formation was identified as constitutional supercooling, extensive modeling was undertaken to identify the optimum welding conditions in order to avoid their formation. The modeling study integrated three different models: a thermal model, a geometric dendrite growth model and a constitutional supercooling model. Calculations were carried out for several different weld conditions and weld orientations. It was found that high weld velocity and low weld power are desirable.