Solid state processing of titanium chips by an unconventional plastic working

Abstract The aim of this paper is to demonstrate how various titanium chips can be processed into solid bulk materials in the form of rods. In this work, an alternative technology for recycling chips without re-melting is presented. In order to transform chips into a new material, an unconventional plastic working method was applied that involved upsetting, heating and extrusion with a rotating die. Two purities of pure titanium were investigated: Ti Grade4 (the lowest possible purity) and high-purity Ti 99.99 (the highest possible purity). For each of these materials, four geometries of chips were processed, i.e. chips after turning (thin and coarse) and chips after milling (thin and coarse). In this paper, the influence of chip purity and chip geometry on the course and effects of the processing were investigated. In addition, technological aspects such as extrusion force and die wear were analyzed. Independent of the type of chips, the results obtained have proved the efficiency and utility of the applied method. As a result of this processing, solid bulk products in the form of rods O8mm in diameter were successfully obtained. The rods were nearly fully consolidated, and their density was practically the same as the density of commercial titanium. The materials obtained exhibited conventional, grained structures. It was also shown that the materials obtained were free from significant structural defects such as porosity and impurities. Additional confirmation of their proper structure and purity was provided by the correct results of hardness (∼200HV, Ti Gr4, and, ∼100HV, Ti hp).