Influence of Annealing at 1100°C and 475°C on the Mechanical Properties at Room Temperature of an Iron Base ODS Alloy

In the last few years the Fe-base oxide dispersion strengthened (ODS) PM 2000 alloy has been shown to be a biomaterial for its outstanding combination of mechanical properties and corrosion resistance. In this work, we are describing the effect of high temperature annealing at 1100°C (pre-oxidation) and low temperature annealing at 475°C on the main mechanical properties at room temperature, with particular emphasis on tensile and fatigue properties, which are suitable for achieving the required biofunctionality of load bearing implants. It has been shown that annealing at 475°C is responsible for an increase in the YS and UTS with the subsequent decrease in ductility. However, despite of the loss of ductility, the material shows ductile behaviour as is observed in the necked zone of tensile specimens, which contrasts with the so-called "475°C embrittlement" observed for another ferritic alloys. Moreover, aged material at 475°C exhibits a better fatigue limit than that non aged pre-oxidised material.