Laser welding techniques for titanium alloy sheet

In order to achieve reliable welds with minimal distortion for the fabrication of components for the aerospace industry, several techniques were explored on Ti6Al4V (Ti64) and Ti6Al2Sn4Zr2Mo (Ti6242) sheets of 1.6 mm and 2 mm thickness using the CO2 and the Nd:YAG pulsed laser. In the tests it was established that: (i) a satisfactory weld can be obtained using the CO2 CW laser with a filler wire: (ii) shaping the edges with a special relief defined as 'built-in filler' before welding enables avoiding using the classical filler wire; (iii) a cosmetic butt weld without filler, obtained by defocussing the CO2 CW laser beam, enables the elimination of the undercut and results in a smooth surface, and (iv) employing a high-power pulsed Nd:YAG laser equipped with fiber optics and a 120 mm focus lens produces autogenous butt welds with full penetration and regular bead profiles, in which undercut and slump can be controlled by proper selection of the pulse energy, pulse duration, frequency, waveform and overlapping rate. (C) 1997 Elsevier Science S.A.