Dynamic research on Ti6Al4V powder HIP densification process based on intermittent experiments

Abstract

The standard hot isostatic pressing (HIP) process at 930 °C/120 MPa for three hours was interrupted into four stages to dynamically study the HIP process on Ti6Al4V powders. The surface chemistry composition of Ti6Al4V powders and the thickness of surface contaminants were analyzed by X-ray photoelectron spectrometry (XPS) technology, and the results show that the oxide layer on the surface of the Ti6Al4V powders is less than 9 nm. Powders compaction simulation was adopted to simplify the analysis of the powder HIP process, and the results show that a large amount of plastic deformation accumulated around the particle boundaries. The microstructure and mechanical properties of specimen of the Ti6Al4V alloy at different HIP stages were investigated. It was found that with the movement and deformation of particles, the final microstructure of the sample shows a typically grid-like morphology composed of the equiaxed α phase and the lamellar β phase, and the α phase is transmitted from the α′ phase. Moreover, the tensile strength of samples fabricated in each interrupted experiment shows that with the prolongation of the HIP process, the overall mechanical properties of the HIP parts are gradually improved, and their final performance reaches the level achieved by forging.