SIMULATION OF HOT ISOSTATIC PRESSING OF A POWDER METAL COMPONENT WITHAN INTERNAL CORE

This paper presents a finite element simulation of the thermomechanica l phenomena occurring during Hot Isostatic Pressing (HIP) of a powder metal component which includes a graphite core. The thermomechanical c oupling is achieved in a staggered step manner. The staggered step app roach considers the coupled thermomechanical response of solids, inclu ding nonlinear effects in both the thermal and mechanical analyses. Th e creep behaviour of the powder material during densification is model led using the constitutive equations of thermal elasto-viscoplastic ty pe with compressibility. The various mechanical material properties ar e assumed to be functions of temperature and relative density. The mec hanical solution also includes large deformation and strains. The ther mal problem includes temperature and relative density dependent specif ic heat and thermal conductivity. The constitutive equations and relat ions for thermal characteristics are implemented into the implicit non linear finite element code, PALM2D. The simulation of the HIP process of a component with internal core is chosen as an application example. The component, injection molding tool, is produced of a hot isostatic ally pressed stainless tool steel with an internal cavity which is ach ieved by inserting a graphite core into the HIP container. To verify t he result of the simulation, the geometry of the capsule and the coate d core are measured both before and after pressing using a computer co ntrolled measurement machine (CMM). The measured geometry is compared with the simulated final shapes of the container and internal core. A computer-aided concurrent engineering system (CAGE) is used for the co mplete manufacturing process from the design of the component and fini te element simulation to the inspection of the final geometry.