On Textural Heredity of Ni-rich Ti-Ni alloy: Specific Features of Transformation and Tensile Behavior

The comparative studies of Ni50.8Ti49.2 wires and strips (processed using cold drawing and rolling, respectively) were carried out using microstructural and thermal characterization, X-ray studies and tensile tests. The axial texture in drawn wires remains stable during subsequent post-deformation annealing (PDA) in the temperature range of 430-800 degrees C. The texture of the as-deformed strips is characterized by the predominance of the component {001} . After PDA at 800 degrees C, the formation of the {111} recrystallization texture is observed along with the persisting texture component {001} . The texture exhibits a pronounced effect on the sequence of martensitic transformations in the temperature range of PDA at 430-600 degrees C. After PDA at 800 degrees C, the calorimetric curves of wires and strips become similar. Both kinds of samples were tensile tested in the temperature range of - 50 degrees C <= T <= + 50 degrees C. The transformation yield stress in strips is lower if compared to wires, this relation does not depend on the microstructure (or PDA mode). The effect of texture on strength characteristics as well as ductility is ambiguous: their ratio between wires and strips depends on microstructure which is determined by PDA mode. The observed regularities are analyzed using structural and textural analyses.