Manufacturing Process for Superalloy Cast Parts. Phase 1. Fundamentals

The report covers Phase I of a two-phase program designed to establish procedures for the manufacture of large, high-integrity, superalloy castings with shipping weights near 100 pounds. A literature survey covering the field of high-integrity and superalloy castings is presented, and a survey of the current and future needs of the aerospace industry. Based on foundry characteristics and the mechanical properties and microstructure of separately cast specimens and specimens cut from cast components with section thickness up to 5 inches, Inco 713LC alloy was selected from among Inco 713LC, Inco 718, and Rene 41 alloys for subscale spin testing and for the Phase II components. The methods of manufacturing a series of spin-test discs for evaluation of the alloy and process for the turbine rotor application are presented, together with the procedures adopted for overcoming a serious problem of residual stresses in the cast and heat-treated disc. The testing of the spin-test discs has established that the cast rotor can be designed using the same burst criterion as in currently used for forged discs. The mechanical property minimums to which the air-cooled turbine rotor disc was designed in Phase II are presented.