Read/Search this Article
The authors carried out a fatigue test for SUS 316 stainless steel in a living animal body and observed a remarkable deterioration in the fatigue durability of the metal. The test indicated that the degree to which the corrosion resistance of the metal was reduced in the living body was insufficient to form a passivation film on a metal surface because of the low concentration of dissolved oxygen gas in the body fluid (the partial pressure PO_2; 28-78mmHg), and the base metal (iron) was released into the environmental fluid as a metal ion. In order to confirm this corrosion fatigue mechanism, with the concentration of dissolved oxygen gas in a physiological normal saline solution being set equivalent to that of living body fluid, fatigue tests on SUS 316 were made and demonstrated the stress corrosion behavior of the metal in the living body. As a result, remarkable deterioration of the fatigue strength was observed in the low PO_2 normal saline solution, which was the same as that in the living body.