Preparation and properties of oxide dispersion strengthened ferritic stainless steels

The influence of additions of Ti and TiO₂ to a ferritic matrix (Fe–13Cr–1·5 Mo) has been investigated. The alloys were prepared by beating together the TiO₂ and the powders of the different elements constituting the alloy. The beaten powders were then consolidated by hot compaction and hot extrusion in the form of bars which were further hot and cold worked by swaging. The particle size distribution of the beaten powders was determined by dry sieving. The microhardness and oxygen content were also measured. The mean size has been found to decrease with the amount of oxide. The room-temperature tensile properties of these alloys were determined as a function of O₂ content at fixed free Ti content and as a function of Ti content at a fixed O₂ level. It was found that after addition of more than O·25%O₂ (as TiO₂) the strength properties almost reach saturation while the ductility continues to decrease. Addition of Ti at a fixed O₂ level increases the strength continuously and leaves the ductility almost unchanged. The 700°C tensile strength properties show the same trend as at room temperature. The ductility, however, increases with O₂ content and decreases with Ti content. The 700°C creep strength at a stress level of 90Nm m⁻² has also been determined for the same alloys. It follows the trend of the tensile properties. PM/0182.