Functional Properties of Spherical Segments Made of Ti-Ni Alloy with Shape Memory Effect

Abstract
The article is devoted to the investigation of changing behavior of force parameters developing in the material of spherical (buckled) segments at heating, depending on the temperature of overheat and presence of strain concentrators. It is shown that overheats of spherical segments relatively to the temperature of reverse martensitic transformations (A_f) up to 50, 100, 150, 200, 250...600°C influence considerably the impact force and reactive forces. Specifically, the spherical segments exposed to overheat at temperatures in a free state always snap back with a stroke against the obstacle and with development of reactive forces at heating. Overheat of the spherical segments in a fixed state decreased the force parameters, and at annealing (200 – 250 °C), 1h the shape memory effect is suppressed completely. Influence of strain concentrators made up deliberately on the edges of the spherical segments depends on their length. It is shown that notches no more than 0,5 mm long do not influence the impact force and reactive force, while notches ≥ 1,0 mm long cause generation and development of nuclear cracks.