MICROSTRUCTURAL VALIDATION OF PROCESSING MAPS USING THE HOT EXTRUSIONOF P M NIMONIC AP-1 SUPERALLOY/

The microstructural features of hot-extruded Nimonic AP-1 superalloy p owder are presented in this paper. Experiments have been designed to v alidate the processing maps of Nimonic AP-1 microstructurally using a commercial extrusion process, The time average mean strain rate, epsil on(i), has been used as the basis for selection of the extrusion param eter viz., ram speed and extrusion ratio, Extrusion was conducted unde r non-isothermal conditions. The microstructural evaluation of the mat erial extruded in the dynamic recrystallization (DRX) domain of the pr ocessing map exhibited homogeneous deformation and a recrystallized st ructure, free from cracks and shear bands. Adiabatic shear bands and i nter-crystalline cracks seen in the microstructures of other extruded products have been correlated accurately with the instability and crac king regimes of the processing map.