Influence of Thermomechanical Treatment on the Functional Properties of Shape Memory Alloys

Abstract—One of the main factors in improving the reliability of individual components and assemblies of machines is the use of new materials with specific properties, which include superelasticity and shape memory effect. For shape memory metals and alloys, heat treatment is used to ensure the required behavior of materials depending on operating conditions. The research purpose of this study is searching for the regularities of changes in the physicomechanical properties of titanium nickelide-based shape memory alloys depending on the thermomechanical effect. The materials used to carry out the planned studies are divided in accordance with their working conditions: the properties of short-term memory is used for the operation of equipment and components under technical working conditions; the nature of the memory effect manifests itself for a long time or is repeated periodically at the operating temperatures of the equipment, that is, under working conditions. The groups of heat treatment of these materials are identified according to the above-mentioned alloy characteristics. Special technological techniques are used to obtain the shape memory necessary for parts that do not correspond to the semifinished product. The necessity of using heat treatment for shape memory has been revealed. It is found that shape memory heat treatment is not performed if plastic deformation during the production of semifinished products is applied at a temperature of at least 400°C and the shape of a workpiece coincides with the configuration of a semifinished product. It has been proved that, in order to stabilize the size of semifinished products during heat treatment, annealing should be carried out at a temperature of 400–450°C. For shape memory alloys, heat treatment influences the provision of the required physicomechanical and thermophysical properties of materials to be used to achieve specific memory effects in certain parts. For the purpose of the efficient operation of shape memory alloys, heat treatment of the given material has been proposed in accordance with the required characteristics and configuration of a part.