Nova abordagem para fabricação de implantes de titânio puro (Cp Ti) de alta resistência através de extrusão gradual

Abstract

Conventional Severe Plastic Deformation (SPD) processes, such as equal channel angular pressing (ECAP) and high pressure torsion (HPT), have been used for mechanical improvement of commercially pure titanium. These techniques usually impose a relative homogeneous deformation range to the whole material volume. In this way, the mechanical properties generated due to the grain refinement from the process are uniformly distributed throughout the work piece. A new technique, known as Gradation Extrusion, has been developed with the objective to produce a deformation gradient on the piece through a process chain that integrates SPD forming and impact extrusion. This method allows to create a fine-grained structure volume near the surface where the grain size decreases on the radial direction of the extruded bar. This feature could be related to the material properties, providing to the material a high mechanical strength due to the volume near the surface and a relative good ductility due to the less refined core. These properties are interesting for dental implants manufacturing application, where ductility is needed for the inner shape forming at the same time that the application requires a general high mechanical strength. This work aims to investigate the material processing making a first characterization of the titanium behavior within the Gradation Extrusion. A numerical simulation was developed to assist the investigation, and the effective plastic strain of the material was evaluated evidencing a large deformation gradient and achieving a high value in the outer volume of the component, thereby revealing the high potential for improving the relationship between strength and ductility.