Properties of 713LC Compacts, Hot Isostatically Pressed at Supersolidus Temperatures

Nickel-base superalloy (713LC) powders produced by two techniques have been consolidated by a single-stage, hot isostatic pressing operation to obtain fully dense, coarse-grained (ASTM 1-2) material. After heat treatment the compacts produced by powder from the rotating electrode process gave tensile strengths between 95 and 112% of that of the as-cast alloy, and stress rupture lifetimes at 980°C and 152 N/mm2 of between 30 and 63% of the as-cast alloy. Compacts produced from argon-atomized powder were heat-treated to give better 760°C stress rupture strengths than cast 713LC. The tensile and stress rupture ductilities of these compacts were generally lower than those of equivalent cast material. At low temperature the ductility is limited by grain boundary precipitates of carbides and sulfocarbides, and at high temperature (980°C) interstitial elements and impurity elements in solid solution are thought to give rise to grain boundary embrittlement. The relationships between microstructure, mechanical properties, and fracture behavior are examined, and the limitations of supersolidus treatment of these alloys are discussed.