Simulation of the powder forging process for titanium components using a porous metal plasticity model

Abstract

Powder forging is a technique that has been used to produce fully dense near-net parts from metal powders. Due to a “low cost titanium” product manufacturing initiative, targeting a reduction in the cost of titanium components, a titanium powder forging technique has gained significant interest. In titanium powder forging, powder consolidation is a key factor that influences successful component manufacture. Consolidation during titanium powder forging is dependent on the densification and deformation mechanisms involved. In this study, a finite element method is used to model the densification and deformation behaviour of titanium powder compacts during powder forging. The research focuses on developing a simulation capability and identifying a suitable constitutive model to simulate the powder forging process that can predict the relative density distribution. The simulation is carried out in Abaqus software and the results are compared with experimental results. A gamma particle radiography technique is used to compare the experimental density results with the simulated results. The Gurson and Gurson-Tvergaard models are used to predict the relative density of porous titanium powder compacts during upset-powder forging and are used to include the effect of hydrostatic stresses and the extent of densification. Three different modes of densification, related to powder forging were studied i.e. upset forging, hot-repressing and closed die forging. The simulation results indicate that both models can be used to determine the relative density during powder forging. By comparing the simulated results with the experimental results, it is found that the density prediction given by the Gurson-Tvergaard model showed closer agreement with the calculated parameters.