In vivo behavior of a high performance duplex stainless steel

An in vivo investigation of a new high molybdenum and nitrogen duplex stainless steel (25Cr--7Ni--4Mo--0.3N) has been performed. Cylindrical pins and specially developed devices, to test in static conditions the in vivo localized corrosion resistance, made of this new duplex steel and of a common austenitic stainless steel were implanted in rabbit's femurs for 6 and 12 months. After sacrifice, SEM observations and EDS microanalyses to detect metallic ion release were carried out on the femur sections surrounding the pins. Morphologic observations with stereoscope and SEM were performed on the metallic surfaces of the special devices in order to detect the presence of localized corrosion. Both ion release and localized corrosion were observed for the specimens made of austenitic stainless steel, but not for those made of 25Cr--7Ni--4Mo--0.3N duplex stainless steel.