Dynamic Recrystallization in the Shear Bands of Tungsten Heavy Alloy Processed by Hot-Hydrostatic Extrusion and Hot Torsion

Hot-hydrostatic extrusion and hot torsion (HE+HT) were applied to the processing of the as-sintered tungsten heavy alloy (WHA). The dynamic mechanical properties of the WHA processed by HE+HT and the microstructural evolution within adiabatic shear band (ASB) were systematically investigated. The results show that the WHA susceptibility to ASB is much improved, and localized shear bands can be formed in specimens. TEM analysis of ASB shows that the multiplication and rearrangement of dislocation play dominate roles in the dynamic recrystallization (DRX) process within ASB of WHA, and the nano-scaled equiaxed-recrystallized grains within ASB can be formed via repeating the processes including dislocation multiplication, dislocation rearrangement and dislocation annihilation. The investigation result of observed DRX of the WHA firmly supports the rotational dynamic recrystallization (RDR) mechanism in metals.