Microstructure evolution in adiabatic shear band in α-titanium

The microstructure and microtexture of adiabatic shear bands (ASBs) on the titanium side of a titanium/mild steel explosive cladding interface are investigated by means of optical microscopy (OM), scanning electron microscopy/electron back-scattered diffraction (SEM/EBSD) and transmission electron microscopy (TEM). Highly elongated subgrains and fine equiaxed grains with low dislocation density are observed in the ASBs. Recrystallization microtextures (28°, 54°, 0°), (60°, 90°, 0°) and (28°, 34°, 30°) are formed within ASBs. The grain boundaries within ASBs are geometrical necessary boundaries (GNBs) with high-angles. Based on the relations between temperature and the engineering shear strain, the temperature in the ASBs is estimated to be about 776–1142 K (0.4–0.6 Tm). The rotation dynamic recrystallization (RDR) mechanism is employed to describe the kinetics of the nano-grains’ formation and the recrystallized process within ASBs. The small grains within ASBs are formed during the deformation and do not undergo significant growth by grain boundary migration after deformation.