Texture evolution and mechanical anisotropy of cold-rolled Zr-4 alloy tube after recrystallization annealing

This work systematically investigated the texture evolution and mechanical properties of Pilger cold-rolled Zr-4 alloy tubes after annealing. Firstly, the deformed samples were annealed at 723 K, 773 K, 873 K and 1073 K to accomplish different levels of recrystallization. The electron backscatter diffraction (EBSD) results showed that although the microstructure gradually transformed into typical equiaxed grains with the elevation of temperature, the texture did not change remarkably except for a slight variation in the polar density. <1120 > and < 1010 > of grains approximately in the same proportion inclined to the axial direction (AD) of the tubes while the c-axis of the majority grains preferred parallel to the tangential direction (TD). Subsequently, tensile tests were conducted on the equiaxed Zr-4 tubes to the strain of 2%, 9% and 15% along the AD and TD. Massive 85 degrees <1120 > tensile twins were generated during the tangential stretching, which jointly with the pyramidal <a > slip contributed to the higher yield strength and ultimate tensile strength compared with axial tension.