Hot Deformation of Biomedical Titanium Alloys: a Review of Deformation Mechanisms, Constitutive Modeling and Processing Maps Analysis

Biomedical titanium alloys provide a unique mix of favorable biomechanical and biocorrosion characteristics and are lightweight, non-toxic, and highly biocompatible. These qualities make them highly desirable for the fabrication of medical implants. Hot working methods are crucial in producing titanium components as they break down the lamellar microstructure into a finer structure. This phase is essential in shaping the final microstructure and determining the qualities of the components. This review delved into the hot deformability, phase and microstructural evolution, and related constitutive equations used in biomedical titanium flow stress modelling. It describes the counteractive effect of the dynamic recrystallisation (DRX) and dynamic recovery (DRV) deformation mechanisms on the working hardening behaviour of the biomedical titanium alloys after hot deformation processing. It also discusses the effect of forming necklace structures and lamellar kinking structures. Notably, in biomedical titanium alloys, the hot deformation behaviour and dynamic softening effect are significantly influenced by the alloy composition and microstructural characteristics like dislocation movement and grain boundary diffusion. The use of processing maps to identify the instability regime—which includes cracks, flaws and flow instabilities that may arise as the biomedical titanium alloys are undergoing hot processing and to ascertain the best processing conditions is covered in the article. Finally, the article's conclusion includes suggestions for possible future research directions.