Three-dimensional microstructure and texture evolution of Ti35 alloy applied in nuclear industry during plastic deformation at various temperatures

Abstract

Microstructure and texture evolution of Ti35 alloy, which was mainly applied in spent nuclear fuel reprocessing industry, during plastic deformation at various temperatures, was systematically investigated by means of electron microscopy. During plastic deformation at room temperature, the alpha colonies were severely fragmented or elongated viewed along three directions, while containing strong texture of [0001]α//ND. Interestingly, in the subsequent annealing processes, the grains viewed along normal direction (ND) transformed into brick-like morphology with rectangular grain boundaries, while the intensity of texture decreased obviously. At the same time, the grains were equiaxed viewed both along rolling direction (RD) and transverse direction (TD). By contrast, Ti35 alloy went through hot rolling contained numerous 85°<1‾21‾0> tensile and 64°<11‾00> compressive twinning, especially viewed along ND, indicating that deformation twinning, together with dislocation slipping, was the dominant plastic deformation mechanism of Ti35 alloy during hot rolling. After annealing at 923K, these twinning were completely recrystallized and led to an equiaxed microstructure with {0001}α planes perpendicular with ND. Micro-hardness and room temperature tensile tests revealed that deformation twinning played beneficial roles in mechanical property of Ti35 alloy by improving its yield strength as well as elongation.