Manufacturing Process for Superalloy Cast Parts. Phase II. Manufacturing.

Using the mechanical property and foundry data established in Phase I, a typical main fin beam support member and an air-cooled turbine rotor disc were designed as castings. Shipping weights were estimated at 120 pounds and 200 pounds respectively. The high shipping weight of the rotor disc was due to the addition of considerable machine stock to the basic design. After encountering several major problems, procedures were eventually established for successfully producing the main fin beam castings in vacuum-melted and cast Inco 713LC. Properties of the castings tested destructively were excellent, reflecting a high degree of soundness and integrity in the cast part. Successful production of the turbine rotor casting was hampered by many problems, all but one of which were eventually overcome. A highly localized surface pinhole defect in a critical area of the casting was unaffected by several corrective procedures. The area involved had no stock for machining and was considered too critical to risk spin testing of the finished disc. The effect is believed to be associated with unusually servere thermal conditions surrounding the affected area during solidification. It is concluded that the cope and drag ceramic mold process is suitable for large superalloy castings providing extraordinary measures are taken to accomodate the vacuum casting process. Author