to 925 u00b0 c and torsionally deformed at this temperature at a constant shear strain rate of 0 173s 1 in the outer layer to above 60 effective strain at the test temperature of 925 u00b0 c this alloy consists of about 74 alpha phase and 26 beta phase after completion of the deformation the torsion specimen was rapidly cooled in air to room temperature fig1 shows the torque vs twist for the above specimen an initial work hardening period can be seen up to a shear strain of about 0 08 in the cylinder 39 s surface layer it is followed by work softening during the remainder of the test the work softening is believed to be a consequence of the break up of the lamellae in the microstructure it manifests itself in regions of localized shear fig1 contains an illustration of axial and radial cross sections from which representative microstructures were obtained referring to fig2 and 3 the shear bands in the radial cross section micrographs indicate heterogeneous distribution of shear strain the bands are approximately parallel to the axial plane which is subjected to the highest shear stress deviations from the axial plane are as much as 15 u00b0 and are most likely due to adjustment of shear bands to crystallographic slip systems in lamella packets after torsion the lamellae are either severely bent or have transformed into equiaxed grains by a combination of shear and recrystallization in the areas of severest deformation the deformed specimen.