MECHANICAL PROPERTIES OF UNALLOYED TITANIUM VT1-0 PROCESSED USING SELECTIVE LASER MELTING AND SEVERE PLASTIC DEFORMATION

Abstract

Unalloyed titanium VT10 with a record value of the ultimate tensile strength of 1350 MPa obtained using technologies of selective laser melting and rotary swaging. This value exceeds by 3 times the tensile strength of commercially pure titanium produced using conventional technologies and also exceeds the strength values of Ti6Al4V (grade 5) high strength titanium alloy. The reasons of the increase in the strength characteristics of titanium VT10 are the finedispersed marten site obtained due to high crystallization rates in the process of selective laser melting, and its additional refinement during the rotary swaging process. To study the thermal stability of the mechanical properties of titanium VT10 processed using various technologies, research of the effect of annealing temperature in the range of 100–800 °C on the ultimate tensile strength and elongation to failure were carried out. Results have shown that the dependence of the ultimate tensile strength on the annealing temperature for VT10 titanium samples after selective laser melting and rotary swaging has a threestage behavior. The ultimate tensile strength decrease by 25–35% after heat treatment at 800 °C. The values of elongation to failure for VT10 titanium samples processed by selective laser melting and rotary swaging monotonically increase from 8–12 to 18–23% when the annealing temperature grows up to 800 °C. The possibilities of methods of selective laser melting, rotary swaging and heat treatment to control the mechanical characteristics of titanium VT10, which is a promising material for the manufacture of osteointegrable medical implants, are demonstrated. The combined application of the abovementioned methods makes it possible to produce VT10 titanium with a given combination of strength and plastic characteristics in a wide range of values.