Development of exothermically cast single-crystal Mar-M 247 and derivative alloysA low-cost, exothermic directional-solidification (DS) process was developed to produce single-crystal (SC) Mar-M 247 high-pressure turbine blades. Stress-rupture data indicated that SC Mar-M 247 provides only marginal improvements in longitudinal strength relative to the columnar grained DS material. Removal of grain boundary strengthening elements (B, C, Zr, Hf) from the Mar-M 247 composition (which are also melting point depressants) permitted the alloy to be solutioned at significantly higher temperatures. An order of magnitude improvement in rupture life relative to SC Mar-M 247 was observed for several derivative alloys at 103.5 MPa (15 KSI) and 1093 C. Rupture lives of the modified SC alloys were significantly affected by both alloy purity and heat treatment. Critical aspects of vacuum induction refining, exothermic casting technology, alloy development and heat treatment, which contributed to this new class of turbine blades, are reviewed
Document ID
19800061655
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Strangman, T. E. (AiResearch Mfg. Co. Phoenix, AZ, United States)
Hoppin, G. S., III (AiResearch Manufacturing Company of Arizona Phoenix, Ariz., United States)
Phipps, C. M. (Jetshapes, Inc. Rockleigh, N.J., United States)
Harris, K. (AiResearch Mfg. Co. Phoenix, AZ, United States)
Schwer, R. E. (Cannon-Muskegon Corp. Muskegon, Mich., United States)