Sub-Solidus HIP Process for P/M Superalloy Conventional Billet Conversion

Abstract

Recent studies have identified thermo-mechanical conditions for powder UDIMET@alloy 72Oi which resulted in significantly higher ductility of HIP compacts [l]. In this process, the compact is produced by hot isostatic pressing (HIP) at temperatures just below the solidus of the alloy (slightly sub-solidus HIP or SS-HIP). The workability of the resulting as-HIPed material is high enough to allow billet conversion using conventional forging. This new process has the potential of reducing the cost of powdered metal (P/M) billet manufacturing. The results of the present study provide some insight on the mechanisms leading to the enhanced forgeability of the SS-HIP processed UDIMET alloy 720. In addition, a full-scale trial has shown that this new processing route has potential application for future production of high performance turbine disks, with equivalent microstructural and mechanical properties as parts manufactured with the conventional compact plus extrude plus isothermal forging route.