A study on the corrosion fatigue behaviour of laser-welded shape memory NiTi wires in a simulated body fluid

Corrosion fatigue is a fracture process as a consequence of synergistic interactions between the material microstructure, corrosive environment and cyclic loads/strains. It can cause unexpected failure of medical and dental implants in the human body. This study reveals a comparison of corrosion fatigue behaviour between shape memory NiTi wire and its laser weldment using bending rotation fatigue (BRF) test integrated with a specifically-designed corrosion cell. The testing medium was Hanks' salt solution kept at 37.5 °C. Electrochemical impedance spectroscopic (EIS) measurement was carried out to monitor the change of corrosion resistance of the samples during the BRF tests at different periods of immersion time in Hanks' solution. Scanning electron microscopy (SEM) was used to analyse the fracture surfaces. This study provides important information on the susceptibility of NiTi alloy and its weldment to corrosion fatigue in Hanks' solution.