Weldability of beta titanium arch wires.

Beta titanium arch wire segments were joined in a variety of configurations by means of four different commercial welders available to the orthodontist. Test specimens were prepared using the point-to-point and flat-to-flat electrode configurations and a range of settings on each welding apparatus. Tension-shear and tension-twist tests were conducted to determine force values to rupture the welded joints; 90 degrees cold-bend tests provided a measure of relative ductility near the joints compared to the as-received wires. Results indicated that the flat-to-flat electrode configuration is preferred for obtaining strong welded joints with low levels of distortion. Optimum settings have been determined for each of the four welders. Microstructural observations of the beta titanium and joint structure are presented; these are correlated with the energy level settings for the welding process.