Strength of Products Made of Ultrafine-Grained Titanium for Bone Osteosynthesis

Abstract

This paper evaluates the fatigue strength of ultrafine-grained (UFG) Grade 4 Ti in the low-cycle fatigue region, as well as the strength of medical implants (plates and screws) made of UFG Ti under various types of loading in comparison with the strength of products made of coarse-grained (CG) Ti. To produce a UFG state, titanium billets after annealing were processed by the ECAP-Conform technique. The fatigue of the prismatic specimens with a thickness of 10 mm from CG and UFG Ti was tested by the three-point bending method using an Instron 8802 facility. The modeling and evaluation of the stress-strain state in the ANSYS software package for finite-element analysis revealed, in particular, the localization of equivalent stresses in the area of hole edges and at fillets during the tension of the plates. The performed research has demonstrated that medical implants (plates and screws) from UFG Grade 4 Ti have a higher strength under different types of loading (tension, fatigue strength, torsion) in comparison with products from CG Ti. This opens up a possibility for the miniaturization of medical products from UFG Ti while preserving their main performance properties at an acceptable level.

The Effects of Submerged Laser Peening, Cavitation Peening, and Shot Peening on the Improvement of the Torsional Fatigue Strength of Powder Bed Fused Ti6al4v Produced Through Laser Sintering

“…In other words, it is difficult to evaluate the geometric effects of the corners or roundness of the specimen. In practical applications for implants, torsional fatigue properties are particularly important for the shaft and the threaded portion of dental implant [26,70,71], stents [72], vascular implants [73,74] and bone substitutes [75,76]. However, most reports in the literature are devoted to reversed tensile fatigue testing.…”

In Vivo Studies of Medical Implants for Maxillofacial Surgery Produced from Nanostructured Titanium

“…Commercially pure (CP) Ti has especially attractive functional properties but a low strength. Therefore, in recent years, great interest has been shown in the studies and developments related to nanostructured Ti where an ultrafine-grained (UFG) structure is formed through the use of severe plastic deformation (SPD). − The formation of a UFG structure with a grain size at the nano- or submicrometer scale drastically raises the strength properties of Ti. For instance, in grade 4 CP Ti, the formation of a structure with a grain size of about 100 nm increases strength and fatigue life more than 2-fold. , These mechanical parameters are noticeably higher than those of the majority of alloyed commercial alloys.…”