Stainless Steel for Medical Implants

The medical community has been using implants for many years now to help surgical patients with problems connected to cartilage or bone disorders and those who suffer through physical trauma. Implants are also used for breast and butt augmentation. Stainless steel and titanium has been used for implants since the mid 1900s although the initial form was the 302 and 316L.
The 316L was chosen because it has the highest corrosion resistant features when it comes into contact with body fluid. Obviously, you don’t want an implant that rusts or loses its form years after surgery. It will cause a myriad of problems from infection to trauma.
In addition, the 316L has carbon and nickel in its formula which is conducive for stabilizing the austenite in stainless less. The 316L implants have anywhere from 17 to 19% chromium and about 14% nickel content. The implant is also protected with a layer of molybdenum so it can resist corrosion from acid. One ingredient that is never used in stainless steel implants is ferrite because it has a magnetic quality. The downside is a change in form because of heating or a problem with MRI if it is required for the patient.
A recent development with implants is the used of titanium alloys to replace tissue. It is stronger than steel but about 50% lighter. The problem with titanium is that it can get contaminated by different elements such as oxygen, hydrogen, and nitrogen.
This now brings a common question about which to choose for implants: stainless steel or titanium although based on a simple assessment, stainless steel remains to be the most logical choice because it isn’t vulnerable to corrosion from oxygen, nitrogen, and hydrogen.

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