The effects of process variables, like scan speed and laser power, on the quality of bead-on-plate welding of NiTinol sheets were investigated. The measured quality aspects for the weld-bead profile were bead geometry, changes in microstructure, variation of microhardness value along the weld-bead, extent of oxide contamination during welding, Ti/Ni ratio after welding, changes in tensile strength of the welded samples and corrosion behavior of the welded and parent materials. The laser weld-bead profile changed from the shape of a stemless wineglass to that with a prominent leg. Dimensional aspects of weld-bead geometry showed a decreasing trend with increasing scan speed. However, an increasing trend of the same was observed with power. The Ti/Ni ratio on the top surface after welding was found to decrease with scan speed at a particular power. Oxide contamination during welding followed the same pattern of variation as that of the Ti/Ni ratio. Microhardness values gradually increased from the weld centerline to the base metal. Formation of brittle intermetallic compounds reduced the tensile strength of the material after welding. A dual failure mode for the welded sample was observed, whereas a single mode of failure was detected for the parent material. The corrosion properties of the welded samples were better than that of the parent material.

Titanium and its alloys are widely popular for manufacturing of orthopaedic implants. Surface modification of those implants is carried out to improve the biocompatibility. Laser can be used for surface modification to enhance surface biocompatibilty through different routes, surface cladding and alloying being the most common. Laser surface remelting process, being a simpler process with less number of process parameters involved, has potential advantages in industrial environments. This paper discusses the process fundamental of laser surface remelting, and explores the effects of different process parameters on microstructural, topographical, tribological and bio-interfacial aspects of biocompatibility of Ti alloys, as found from existing literature. The limitations associated with laser surface remelting processes are also identified.