Corrosion resistance of a laser spot‐welded joint of NiTi wire in simulated human body fluids

Abstract The purpose of this study was to investigate corrosion resistance of a laser spot‐welded joint of NiTi alloy wires using potentiodynamic tests in Hank's solution at different PH values and the PH 7.4 NaCl solution for different Cl⁻ concentrations. Scanning electron microscope observations were carried out before and after potentiodynamic tests. The composition of a laser spot‐welded joint and base metal were characterized by using an electron probe microanalyzer. The results of potentiodynamic tests showed that corrosion resistance of a laser spot‐welded joint of NiTi alloy wire was better than that of base metal, which exhibited a little higher breakdown potential and passive range, and a little lower passive current density. Corrosion resistances of a laser spot‐welded joint and base metal decreased with increasing of the Cl⁻ concentration and PH value. The improvement of corrosion resistance of the laser spot‐welded joint was due to the decrease of the surface defects and the increase of the Ti/Ni ratio. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006