Advances in development of titanium alloys for spinal fixation applications titanium alloys with high fatigue strength and low springback for spinal fixation applications

Mitsuo Niinomi, Masaaki Nakai, Junko Hieda, Ken Cho, Kengo Narita

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The fatigue strength of the newly developed ?-type titanium alloy Ti-29Nb-13Ta-4.6Zr (referred to as TNTZ) is important for its applications in spinal fixation rods. Enhancements in the fatigue strength of TNTZ upon solution treatmnet and thermo-mechanical processing (aging after severe cold-caliber rolling or sever cold-swaging) have been investigated. Aging the rods at 723 K for 259.2 ks after cold-swaging is shown to be the optimal thermo-mechanical processing method for the TNTZ rod , yeilding a high 0.2% proof stress of about 1200 MPa, high elongation of 18%, and high fatigue strength of 950 MPa. High springback is undesirable for application of TNTZ spinal-fixation rods. To reduce springback, a High Young's modulus is required; on the other hand, a low Young's modulus is beneficial to reduce bone absorption and obtain good bone remodeling. To achieve a balance between these two factors, TNTZ has been modified by adding Cr to obtain an alloy with a high Young's modulus at the deformed region and a low Young's modulus throughout the undeformed region. TNTZ-8Ti-2Cr and TNTZ-16Ti-4Cr are novel alloys whose β phase is more stable than that of TNTZ. Only the β phase is present in these alloys, which exhibit relatively low Young's moduli of <65 GPa after solution treatment, and higher Young's moduli after cold rolling, owing to a deformation-induced ω-phase transformation. These modified TNTZ alloys show significantly less springback than the original TNTZ, based on tensile and loading-unloading bending tests.

Original languageEnglish
Title of host publicationRecent Highlights in Advanced Materials
PublisherTrans Tech Publications Ltd
Pages446-452
Number of pages7
ISBN (Print)9783037858295
DOIs
Publication statusPublished - 2014 Jan 1
Event2nd International Congress on Advanced Materials, AM 2013 - Zhenjiang, China
Duration: 2013 May 162013 May 19

Publication series

NameKey Engineering Materials
Volume575-576
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795

Other

Other2nd International Congress on Advanced Materials, AM 2013
CountryChina
CityZhenjiang
Period13/5/1613/5/19

Keywords

  • ?-type titanium alloy
  • Mechanical properties
  • Spinal fixation
  • Tntz
  • Young's modulus

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Niinomi, M., Nakai, M., Hieda, J., Cho, K., & Narita, K. (2014). Advances in development of titanium alloys for spinal fixation applications titanium alloys with high fatigue strength and low springback for spinal fixation applications. In Recent Highlights in Advanced Materials (pp. 446-452). (Key Engineering Materials; Vol. 575-576). Trans Tech Publications Ltd. https://doi.org/10.4028/www.scientific.net/KEM.575-576.446