Next Article in Journal
An Investigation into Creep Cavity Development in 316H Stainless Steel
Next Article in Special Issue
The Role of Hydrogen in Hydrogen Embrittlement of Metals: The Case of Stainless Steel
Previous Article in Journal
Review of Aluminum-To-Steel Welding Technologies for Car-Body Applications
Previous Article in Special Issue
Ab Initio Study of the Combined Effects of Alloying Elements and H on Grain Boundary Cohesion in Ferritic Steels
Open AccessArticle

Hydrogen Effect on the Cyclic Behavior of a Superelastic NiTi Archwire

Laboratory of Mechanics of Sousse, National Engineering School of Sousse, University of Sousse, Sousse 4054, Tunisia
Department of Mechanical Engineering, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia
Laboratory of Electromechanical Systems (LASEM), National Engineering School of Sfax, University of Sfax, Route de Soukra km 4, Sfax 3038, Tunisia
Research Center for Advanced Materials Science (RCAMS), King Khalid University, PO Box 9004, Abha 61413, Asir, Saudi Arabia
Author to whom correspondence should be addressed.
Metals 2019, 9(3), 316;
Received: 13 February 2019 / Revised: 4 March 2019 / Accepted: 7 March 2019 / Published: 11 March 2019
In this work, we are interested in examining the strain rate effect on the mechanical behavior of Ni–Ti superelastic wires after hydrogen charging and ageing for 24 h. Specimens underwent 50 cycles of loading-unloading, reaching an imposed deformation of 7.6%. During loading, strain rates from 10−4 s−1 to 10−2 s−1 were achieved. With a strain rate of 10−2 s−1, the specimens were charged by hydrogen for 6 h and aged for one day showed a superelastic behavior marked by an increase in the residual deformation as a function of the number of cycles. In contrast, after a few number of cycles with a strain rate of 10−4 s−1, the Ni-Ti alloy archwire specimens fractured in a brittle manner during the martensite transformation stage. The thermal desorption analysis showed that, for immersed specimens, the desorption peak of hydrogen appeared at 320 °C. However, after annealing the charged specimens by hydrogen at 400 °C for 1 h, an embrittlement took place at the last cycles for the lower strain rates of 10−4 s−1. The present study suggests that the embrittlement can be due to the development of an internal stress in the subsurface of the parent phase during hydrogen charging and due to the creation of cracks and local zones of plasticity after desorption. View Full-Text
Keywords: hydrogen; NiTi alloys; superelastic; martensite; cyclic effect hydrogen; NiTi alloys; superelastic; martensite; cyclic effect
Show Figures

Figure 1

MDPI and ACS Style

Sarraj, R.; Kessentini, A.; Hassine, T.; Algahtani, A.; Gamaoun, F. Hydrogen Effect on the Cyclic Behavior of a Superelastic NiTi Archwire. Metals 2019, 9, 316.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop