Medical Grade Titanium
Medical grade titanium and its use in the medical industry is one of the primary applications of titanium. Whilst titanium is bio-compatible additional controls are implemented to ensure safety for its usage.
Commercially Pure titanium have been used successfully in human medical implants for well over two decades both in contact with bone and soft tissue. Unalloyed titanium has has a high biological response and makes for an ideal medical Material
The additional control for medical grade titanium build on top of existing standards for the production of bars, tubing, strip and plates. Furthermore the controls differ from Unalloyed Commercially Pure titanium and Alloyed Titanium. The rationale for defining such additional controls is to outline an acceptable chemical composition range which is suitable for medical applications.
Medical Titanium Unalloyed Titanium Grades
First for consideration are the four titanium grades of unalloyed CP titanium used for the manufacture of surgical implants.
During manufacture the titanium is furnished in either the stress relived, annealed, cold-worked, hot-rolled or forged condition. With finishing taking due care to ensure the material is without both internal and external issues. As such the material can be sandblasted, pickled, descaled or a combination. In order to remove any imperfections these are done by spot grinding however obviously not impacting the dimensions or tolerances of the material.
The medical grades are defined as UNS Numbers: UNS R50250, UNS R50400, UNS R50550, UNS R50700 and the composition can be found below.
Standards Specifically covering the use of Unalloyed Titanium Grades include ASTM F67 – Standard Specification for Unalloyed Titanium, for Surgical Implant Applications (UNS R50250, UNS R50400, UNS R50550, UNS R50700)
Medical Titanium Alloyed Titanium Grades
Medical grade titanium in an alloyed form is known as Titanium-6Aluminum-4Vanadium Extra Low
Interstitial (ELI) which is a metal commonly found at use in surgical implants.
The material is manufactured in traditional mills with standard equipment including forging and rolling machines. The titanium alloy is melted in arc furnaces several times typically done with reactive metals. Again as with CP medical titanium the product is furnished with pickling, mechanical descaling, chemically milled, ground, peeled, machined or polished.
The primary difference for medical titanium is the major and minor elemental constituents as given below along with the permissible residual elements.
Standards Specifically covering the use of Unalloyed Titanium Grades include ASTM F136 Wrought Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for Surgical Implant Applications (UNS R56401)