SECONDARY RECRYSTALLIZATION OF 2 OXIDE DISPERSION-STRENGTHENED FERRITIC SUPERALLOYS - MA-956 AND MA-957

The response to isothermal recrystallisation and zone recrystallisation of rods of MA 956 and MA 957 has been compared. Isothermal recrystallisation produced equiaxed millimetre sized grains in MA 957, whereas MA 956 had grains of high aspect ratio. This is attributed to an anisotropic distribution of oxide particles in MA 956. In both alloys the initial strong [110] fibre texture is transformed into textures lying on the [001]-[111] zone axis. A discrete zone recrystallisation interface could not be formed in MA 956 under the range of conditions investigated. This may be ''counted for by an anisotropic boundary pinning force. This results in small transverse velocities and also a different zone recrystallisation texture in MA 956 from that in MA 957.