Weld speed effects on quality of Ti/Al dissimilar metal joints using laser beam welding

Abstract

Laser beam welding produces good quality welds with minimum shrinkage for sheet metal joints. The quality of welded joint depends upon surface morphology, hardness, mixing of liquid phases and metallurgical non-homogeneity induced by gradients of temperatures and cooling rate at the weld interface. In the present investigation, Titanium Grade5 (Ti) and AA2024 (Al) alloy dissimilar sheet metals are joined using Nd:YAG pulsed laser beam and the effect of welding speed on crack tendencies, the strength of weldment based on hardness and composition changes are studied. Test results reveal that higher welding speed eliminates cracks in weldment and improves surface morphology. From hardness test, it is observed that the strength of fusion zone is considerably improved at higher weld speed and the findings are supported by SEM and EDS studies.Keywords: laser beam welding; LBW; morphology; hardness; microstructure; composition.Reference to this paper should be made as follows: Kalaiselvan, K., Elango, A. and Nagarajan, N.M. (2017) N.M. Nagarajan is a retired Professor from National Institute of Technology, Calicut, Kerala, India. His current research deals with powder metallurgy, metal joining, foundry and control of welding processes. He has authored and co-authored more than 100 technical papers.

Pulsed Nd: YAG Laser Dissimilar Welding of Ti/Al3105 Alloys

“…Experimental results show that a welding speed of 4 mm.s -1 (76% overlapping) results in a deeper penetration(342 µm) than the higher welding speed of 6.67 mm.s -1 (60% overlapping) (184 µm). This is due to the input of a stronger focal energy at the lower speed which is in agreement with the mechanism described by the previous authors [18,33]. In last pulse region (end spot of the ring welding path), there are three pulses which collide to the same place before the laser power-supply turns off and the moving head wholly stops.…”