Container influence on shrinkage under hot isostatic pressing—II. Shape distortion of cylindrical specimens

Finite element modeling of the cylindrical specimenʹs shape distortion due to the con tainer influence under HIPing is carried out. It is assumed that the mechanical behavior of the powder and the container obeys power law creep equations, and an extremum principle of minimum energy dissipation is taken as the basis of the finite element approach. The specific features of the proposed numerical methods are the utilization of special axisymmetrical shell elements for the container and the iterative approach of the viscous approximations for the solution of the nonlinear flow equations. It is noted, that the container influence on the shape change of the specimen depends on the magnitude of the power law creep exponent and distortions are more intensive in the case of low temperature creep. The method for the estimation of the container ribsʹ influence on the shape deviation is proposed. In many cases, it is possible to produce a precise final shape of the part by the determination of the initial shape of the porous specimen. The iterative method for the prediction of the necessary initial shape is put forward. The method is based on the use of reverse calculations from the final to the initial shape. © 1998 Elsevier Science Ltd. All rights reserved