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Stress Corrosion Cracking

Over the last several decades there has been a great deal of conjecture and some studies reported in the literature concerning the possibility for in vivo stress corrosion cracking of alloys used for biomedical applications. Many of the reported incidences identifying stress corrosion cracking as the mechanism of failure of retrieved implants occurred before the 1970’s. Most of these reports implicated 316L stainless steel while only a few ascribed this failure mechanism to certain grades of CP titanium. Most of the fundamental research studies were performed in saline solution at 37ºC and some were also performed using more aggressive media at elevated temperature. Because of a lack of definitive correlation between these early reports, and because the composition of implant quality 316L stainless steel has been redefined, we embarked upon a program to assess the stress corrosion cracking behavior of these materials under the same conditions. We have begun by evaluating both the entire process to failure of the three most commonly used stainless steels, CP titanium, two a/ß titanium alloys, and a ß titanium alloy. All of this research to date is in the literature or shortly will be. We are continuing with this specific work to include all of the alloys used for biomedical applications, as well as expanding this area of research to include studies on the crack propagation phase.