title: Evolution of the microstructure and mechanical properties during fabrication of mini-tubes from a biomedical β-titanium alloy.
abstract: The processing of Ti-25Nb-3Mo-3Zr-2Sn tubes with outside diameters of 5.6-8.0 mm and wall-thicknesses of 0.7-1.0 mm were investigated in order to study the evolution of microstructure and mechanical properties and their impact on the processing of the tubes. The annealed small tubes with single β phase microstructures exhibit double yielding during tensile tests. The onset of martensitic phase transformation was observed to occur after the lowest point of the strain hardening. Cold rolling also activates the formation of the stress induced martensitic α″ phase. Its volume fraction increased with increasing ε. The rate of strain hardening and the modulus of the tubes are related to the stress induced transformation of the β phase to the α″ phase. The stress induced α″ slightly improves the yield strength of the tubes at low levels of strain. However, larger strains result in grain growth during annealing, which diminishes the mechanical properties.
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: y.zhang20@uq.edu.au.
authors.forename: Yaowu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Damon
authors.initials: D
authors.lastname: Kent
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Gui
authors.initials: G
authors.lastname: Wang
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: David
authors.initials: D
authors.lastname: St John
authors.affiliation: Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Dargusch
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D008422:Materials Testing; D055595:Mechanical Phenomena; D044367:Phase Transition; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; C023988:beta titanium; D014025:Titanium
keywords: Annealing; Cold rolling; Double yielding; Martensitic transformation; Metastable β-titanium alloy