MECHANICAL PROPERTIES OF A ROD FOR SPINAL DEFORMITY CORRECTION PRODUCED FROM META-STABLE BETA Ti-Cr-Sn-Zr ALLOYS

摘要

Titanium shows excellent biomedical compatibility and some meta-stable beta Ti alloys show shape memory, low Young's modulus, and super-elasticity, which are useful properties for biomedical application. We have investigated rolled sheets of such meta-stable beta Ti-Cr-Sn-Zr alloys with low Young's modulus. However, rod shaped Ti alloy specimens similar in dimensions to a spinal fixation rods have not been so investigated. We experimentally produce a rod similar to those used for spinal deformity correction using a multi-pass groove rolling. The rod shows two-step yielding in a tensile test's stress-strain curves due to stress induced martensitic transformation and flow stress was slightly higher than the sheet specimen. The rod showed low Young's modulus and super-elasticity.