Dissimilar pulsed Nd:YAG laser welding of pure niobium to Ti–6Al–4V

Dissimilar butt welding of pure niobium plate to the titanium alloy Ti–6Al–4V sheet using a pulsed Nd:YAG laser is performed. Effects of laser pulse energy, duration and repetition rates on the melt profile on both sides of the weld line were investigated. Considering the thermo-physical properties of the two base metals, variation of the weld profiles on different sides of the weld line is discussed. Through optimization of the process parameters a sound weld with full penetration along the dissimilar interface was obtained. However, islands of Ti rich and Nb rich phases were identified in the weld metal. Tensile strength of the welded joints matched that of the weaker base metal i.e. niobium and the specimens broke outside the fusion line.