Influence of Precipitation and Grain Size on the Hot Ductility of Alloy C-276 ESR Ingots

The influence of precipitation and grain size on the hot ductility of alloy C-276 ESR ingots has been determined.Tensile tests were performed in the temperature range of 950 to 1200°C at a strain rate of 6.1 /sec.The precipitation of the Ρ phase in this alloy revealed a detrimental influence on the hot ductility, because these precipitates tend to fracture prior to grain boundary sliding and dynamic recrystallization during deformation, and hence favor a low ductility cleavage fracture.Isolating the influence of precipitation from that of solution treatment for 2 hours showed that a considerable dissolution of the precipitates induced a significant improvement in the hot ductility, giving the mechanism for grain boundary sliding and dynamic recrystallization during deformation.Hot ductility drops at 1050 and 1200°C are attributed to the precipitation reprecipitated especially at grain boundary before deformation and grain boundary weakening at high temperatures, respectively.However, the worst hot ductility occurred when the solution of precipitates and grain growth were generated and the precipitates were reformed again in a fine form especially at the grain boundaries before deformation at intermediate temperatures.