SUPERALLOYS MADE BY CONVENTIONAL VACUUM MELTING AND A NOVEL SPRAY FORMING PROCESS

Wrought Ni-base superalloys used in modern gas turbine engines are typ ically produced by vacuum induction melting (VIM) plus consumable reme lting (ESR and/or VAR). For the more advanced alloys, these processes have certain limitations; namely, the ability to produce sound ingots of a reasonable size, free of harmful segregation related defects, whi ch can readily be converted into wrought product. Powder metallurgy pr ocesses have been developed to overcome these problems but substitute another problem: high cost. To address these concerns, a clean, cerami cless spray forming process has been developed which uniquely combines electroslag remelting (ESR), bottom pouring through a cold induction guide (CIG) and spray forming (Osprey Metals Ltd). This paper discusse s some of the issues encountered in current superalloy manufacturing p rocesses and describes the clean metal spray forming (CMSF) plant whic h has been constructed to address them. Copyright (C) 1996 Elsevier Sc ience Ltd.