Densification and Deformation Behaviors for Near-Net-Shaped Metal Powder Compacts under Hot Isostatic Pressing

Abstract

This thesis reports the effect of the stacking fault energy on densification and deformation behaviors of metal powder at high temperature during hot isostatic pressing process. Experimental data for densification behavior, relative density distribution, and final deformed shape of powder compacts of 316L stainless steel and nickel-based superalloy were obtained under hot isostatic pressing. The constitutive model of Abouaf et al. was modified by considering the stacking fault energy as a material parameter. The relative density functions were obtained for 316L stainless steel and nickel-based superalloy after considering the stacking fault energy as a material parameter. The developed model with stacking fault energy-dependent parameter was implemented into a finite element program (Abaqus – FEA). The finite element calculations were compared with experimental data for densification and deformation behaviors of 316L stainless steel and nickel-based superalloy powders during hot isostatic pressing. The proposed constitutive model was also examined to predict densification and deformation behaviors of 316L stainless steel powders in the literature. The finite element calculations from the new model accurately predicted various experimental data, and by employing the stacking fault energy in the constitutive equations of metal powders, better theoretical results were obtained compared to the original model. This thesis also reports the effect of glass container encapsulation on deformation and densification behaviors of 316L stainless steel and nickel-based superalloy powders during hot isostatic pressing. Finite element calculations from Abaqus – finite element analysis (FEA) were compared with measured deformed shapes of powder compacts. Finally, samples deformed in glass containers were compared with other samples deformed in metal containers to study the capabilities of glass containers to form near-net-shape parts. Glass container showed more homogeneous densification and isotropic deformation of compacts than conventional metal containers.