Analytical Modeling of the Hot Isostatic Pressing Process.

This report describes the results of a two-year investigation to develop a modeling strategy to predict the final shape of components manufactured by the Hot Isostatic Pressing HIP process. When a powder metal is subjected to the high pressures at high temperatures there is a permanent reduction in the macroscopic volume by approximately 30 percent. The volume reduction, which is not included in classical creep and plasticity theories, necessitates the modification of the classical theories. The major part of this report concerns development of a constitutive model for powder metals. A model for powder metals subjected to an external hydrostatic pressure has been developed and compares well with experimental results. The exact form oof the theory for a multi-axial stress state was determined by a series of mechanical tests. The constitutive model has been incorporated into the MACR nonlinear finite element computer program and analysis of an independent experiment using the modified code has been performed and verified the accuracy of the theory. Once the theory had been verified it was applied to the HIP of a disk and a sensitivity study was performed to determine an efficient modeling strategy. The results of the program are discussed in detail. Author