Fusion welding studies using laser on Ti–SS dissimilar combination

Laser welding investigations were carried out on dissimilar Ti–SS combination. The study is aimed to improve the weld strength and ductility by minimizing harmful intermetallics and taking advantage of high cooling rates in laser welding. Results of continuous wave 3.5 kW CO2 laser welding of totally dissimilar combination of Titanium and stainless steel (304) have been discussed. Bead on plate welding experiments were conducted to identify the laser welding parameters using depth of penetration as criteria. The welding of dissimilar combination has been attempted both autogenously and with interlayers such as Vanadium (V) and Tantalum (Ta) in the form of laser cladding as well as strip. Autogenous welds were carried out by varying the laser power, welding speed and position of the laser beam with respect to the joint centre. The resultant welds are characterized by macrostructure analysis, SEM/EDAX and XRD and as welded tensile test in UTM. The autogenous welds have exhibited extensive cracking even when welded at high speeds or by manipulating the beam position with respect to the joint. Similarly Vandaium as interlayer could not achieve crack free joint. A joint with 40 MPa strength could be made with Ta as interlayer. Results and analysis of these variants of laser welded joints are reported and discussed.

► Laser fusion welding studies have been carried out on Ti–SS dissimilar material combination both autogenously and with the addition of suitable interlayers.
► The idea is to reduce or control the growth of intermetallics with the use of enhanced cooling rates.
► In that context autogenous laser welding was attempted with the maximum welding speeds possible.
► The interlayers attempted are Vanadium, Tantalum in the form of both powder and strip.
► The resultant welds were characterized to study the phases and the joint strength.