Microstructural validation of processing maps using the hot extrusion of P/M Nimonic AP-1 superalloy

Abstract

The microstructural features of hot-extruded Nimonic AP-1 superalloy powder are presented in this paper. Experiments have been designed to validate the processing maps of Nimonic AP-1 microstructurally using a commercial extrusion process. The time average mean strain rate ε_t, has been used as the basis for selection of the extrusion parameter viz., ram speed and extrusion ratio. Extrusion was conducted under non-isothermal conditions. The microstructural evaluation of the material extruded in the dynamic recrystallization (DRX) domain of the processing map exhibited homogeneous deformation and a recrystallized structure, free from cracks and shear bands. Adiabatic shear bands and inter-crystalline cracks seen in the microstructures of other extruded products have been correlated accurately with the instability and cracking regimes of the processing map.