Modeling of Hydrogen Diffusion Towards a NiTi Arch Wire Under Cyclic Loading

• Published in: Metals and materials international 2021, 27(3), , pp.413-424
• Main Authors: Sarraj, Riheme, Letaief, Wissem Elkhal, Hassine, Tarek, Gamaoun, Fehmi, El Ouni, Mohamed Hechmi
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Arches; Characterization and Evaluation of Materials; Chemistry and Materials Science; Computer simulation; Constitutive models; Corrosion resistance; Cyclic loads; Energy dissipation; Engineering Thermodynamics; Finite element method; Heat and Mass Transfer; Hydrogen; Hydrogen storage; Intermetallic compounds; Machines; Magnetic Materials; Magnetism; Manufacturing; Martensite; Martensitic transformations; Materials Science; Mathematical models; Mechanical properties; Metallic Materials; Nickel base alloys; Nickel titanides; Orthodontics; Processes; Room temperature; Shape memory alloys; Solid Mechanics; Subroutines; Superelasticity; Wire; 재료공학
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-019-00425-w

NiTi shape memory alloys belong to a class of metals with specific properties like corrosion resistance and biochemical compatibilities. These characteristics allow their use in a lot of medical fields, especially as arch wires in orthodontic applications. A significant alteration of the superelasticity of orthodontic arch wires can be notified after a few months of use in the oral cavity. This behavior is due to the presence of hydrogen. The objective of this work is to develop a constitutive model, which describes the effect of the degradations of the mechanical behavior of NiTi shape memory alloys caused by cyclic loading and hydrogen diffusion. To experimentally predict such effects, orthodontic specimens are charged by hydrogen in a 0.9% NaCl aqueous solution at room temperature with a current density of 10 A/m 2 for 2 h, 3 h, 4 h and 6 h and are aged for 7 days in air. The obtained curves display an increase in the critical stress at the beginning and end of the martensite transformation and a decrease in the dissipated energy compared by the curve obtained by a non-charged wire. The developed model is implemented in ABAQUS software through the UMAT and UMATHT subroutines. Finally, the numerical simulation, based on the model proposed in our work, shows a good concordance with the experimental data. Graphic Abstract