Structural Analysis of Plastic Deformation around the Crack Initiated in Austenitic Stainless Steel

Metallic implants should have the following basic characteristics as excellent biocompatibility, high corrosion resistance, suitable mechanical properties (strength, fracture toughness...) and high wear resistance in order to serve safely and adequately for a long-time period without rejection. Austenitic stainless steels are popular for implant applications because of their availability, lower cost, excellent fabrication properties, accepted biocompatibility and toughness. The mechanical working conditions within human body are tough, because surgical implants are subjected to static and dynamic mechanical loading and exposed to surrounding aggressive environment such as human body. As the material is subjected to cyclic loading, micro-plastic deformation occurs around the crack [1,2]. The aim of this paper is to observe the area around the originated crack on the testing bar. The microstructural analysis of initial state and after three-point bending was performed by optical and scanning electron microscopy. Hardness measurement was performed under the crack originated after cyclic loading.