Analysis of Densification and Consolidation during the Solid-State Recycling of High Purity Titanium Chips (vol 2022, pg, 2022)

In this work, the phenomena of densification and consolidation which took place during the solid-state recycling of titanium chips are investigated and discussed. This transformation into a solid material consisted of (1) a preliminary densification of the chips achieved by upsetting, and (2) final densification and consolidation achieved by direct extrusion combined with the cyclical rotation of the die. The material investigated was high purity, single-phase titanium. Two geometries of chips were investigated, i.e., chips after turning and after milling. In this paper, the results of complex macroscopic and microscopic research are presented. Furthermore, the conditions necessary for plastic consolidation are analyzed. As an effect of the processing applied, a dispersed form (chips) was transformed into a monolithic, solid form (rods with a diameter of Ø8mm and a length of between 400 and 700 mm). Both types of chips were densified and consolidated. Characteristic zones in the material were revealed and were discussed. It was found that the manufactured materials were fully dense (4.48-4.50 g/cm3) and exhibited coherent structures with new inter-atomic bonds. These structures were free of significant internal defects such as pores (average porosity 0.008%). The investigations showed that, during extrusion, a gradual plastic diffusion-less consolidation occurred. The rods obtained exhibited a proper structure typical for commercial titanium in the as-received state. © 2022, ASM International.