Open AccessImpact of thermocycling type on nature of changing reversible deformations in titanium nickelide
Author(s) -
S. V. Kryuchkov,
Н. П. Богданов,
V. G. Malinin,
V. L. Savich,
М. Н. Коновалов
Publication year - 2019
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/656/1/012029
Subject(s) - materials science , diffusionless transformation , austenite , shape memory alloy , martensite , plasticity , metallurgy , titanium , nickel titanium , composite material , torsion (gastropod) , deformation (meteorology) , austenitic stainless steel , microstructure , medicine , surgery , corrosion
For cyclic functioning of mechanisms for various functional purposes based on materials with a shape memory effect (SME), it is necessary to possess skills of forming the characteristics of a cyclic shape memory, i.e. the shape memory effect implemented upon heating and plasticity of direct transformation observed upon cooling of the material under load. For this purpose, a systematic experimental research of the impact of a type (mode) of thermocycling of samples of titanium nickelide under torsion on the nature of changing reversible deformations in the process of thermocycling was performed. To assess quantitatively the effectiveness of a thermocycle, the value of a thermocycle completeness coefficient was introduced which is determined as the ratio of the value of the deformation restored for a cycle to the value of the deformation accumulated for a thermocycle. Three modes of loading were studied. 1. The material was loaded in a martensitic state to a certain level, then it was heated through the interval of a reverse martensitic transformation, in the austenitic state it was unloaded and cooled to its original state. 2. The material was loaded in a martensitic state, then heated through the interval of a reverse martensitic transformation to an austenitic state and cooled to its original state. 3. The material loaded in a martensitic state was unloaded. Then it was heated through the interval of a reverse martensitic deformation to an austenitic state in a free state, where it was loaded and the loaded material was cooled to a martensitic state. For all thermomechanical modes of loading upon heating, the value of the deformation restored and accumulated upon cooling was defined experimentally. It has been experimentally found that the highest value of the restored deformation is implemented in the third loading mode, and the lowest one – in the first one. The intermediate deformation is implemented in the second mode. The highest value of the deformation determined by the effect of the direct transformation plasticity takes place in the third mode.