Effect of temperature on fatigue of superelastic NiTi wires

•Unrecovered strain is generated in martensitic transformation under external stress.•The unrecovered strain is proposed to quantify accumulation of microstructure damage.•Microstructure changes/damage significantly increases with increasing temperature.•Superelastic fatigue life correlates with acc...

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Bibliographic Details
Published in:International journal of fatigue 2020-05, Vol.134, p.105470-10, Article 105470
Main Authors: Tyc, Ondřej, Heller, Luděk, Vronka, Marek, Šittner, Petr
Format: Article
Language:English
Subjects:
Crystal defects
Damage accumulation
Deformation analysis
Fatigue
Fatigue failure
Fatigue life
Fatigue tests
Intermetallic compounds
Martensitic transformations
Materials fatigue
Nickel base alloys
Nickel titanides
NiTi alloy
Plastic deformation
Shape memory alloys
Superelasticity
Temperature effects
Unrecovered strain
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Summary:•Unrecovered strain is generated in martensitic transformation under external stress.•The unrecovered strain is proposed to quantify accumulation of microstructure damage.•Microstructure changes/damage significantly increases with increasing temperature.•Superelastic fatigue life correlates with accumulation of unrecovered strain. The stress induced martensitic transformation in superelastic NiTi alloy can be accompanied by a plastic deformation. In this work, NiTi wires were subjected to tensile displacement-controlled tests in the temperature range −90 °C to 190 °C and lattice defects created by the deformation were analysed by TEM. The unrecovered strain significantly increased and fatigue life decreased with increasing test temperature. The rate of the accumulation of unrecovered strain in the stabilized stage of tensile cycling was taken as an indicator of the accumulation of material damage. Fatigue life ranged from 900 cycles at 80 °C to 4700 cycles at 15 °C.
ISSN:0142-1123
1879-3452
DOI:10.1016/j.ijfatigue.2020.105470