Secondary recrystallisation of MA 957 oxide dispersion strengthened ferritic superalloy

Abstract

Secondary recrystallisation has been studied in MA 957 oxide dispersion strengthened ferritic superalloy following heat treatment at a temperature of ∼1320°C. Selected area channelling patterns in the scanning electron microscope were used to characterise the crystallographic texture of grains of large aspect ratio produced by zone annealing and microbeam electron diffraction was used to determine the orientations of submicrometre, equiaxed grains behind the (secondary) recrystallisation front. MA 957 exhibits a dominant 〈110〉 texture in the as extruded condition, but this texture is notably absent after recrystallisation. At high zoning speeds the material displays a 〈113〉 texture, but an increasing proportion of 〈111〉 texture component is evident as the zoning speed is reduced. The texture development can be tentatively rationalised in terms of the influence of solute segregation processes and grain orientation on interfacial mobility.

MST/1555