Abstract：Ti-Ni superelastic wires are often faced with the problem of hydrogen embrittlement when applied to dental orthodontic arch wires.In this paper, samples with B2 and R phases at room temperature were obtained by heat treatment, and the hydrogen embrittlement behaviors of the two samples were compared. The results show that under the same hydrogen charging process, the samples with R phase at room temperature have higher elongation and tensile strength.In addition, the critical stress value of the stress-induced B2→B19' phase transition increases significantly with the hydrogen charging time, indicating that hydrogen will significantly hinder the B2→B19' martensitic phase transition, while hydrogen has little effect on the critical stress level of the stress-induced R→B19' phase transition.Fracture analysis shows that with the extension of hydrogen charging time, the area shrinkage rate of the two samples with B2 and R phases at room temperature decreased significantly, and the fracture mode changed from ductile fracture to brittle fracture.The ductile fracture to brittle fracture transition of samples with R-phase microstructure at room temperature is less affected by hydrogen charging.The above studies show that the hydrogen embrittlement susceptibility of Ti-Ni superelastic wires can be reduced by introducing R phase.
2022, Vol. 29 