Optimisation of performance characteristics in laser welding of Nitinol wires using Taguchi and grey relation analysis.

NiTi Shape Memory Alloy (SMA) finds wide applications in high-performance engineering industries such as medical devices, micro-electrical and electronic components, aerospace, aircraft structure, and so on, to name a few. This is owing to its superior properties like shape memory effect (SME), superelasticity, and biocompatibility. However, getting a proper joining of NiTi alloys is hard considering its unique characteristics. Therefore, joining this alloy has been a domain of great attention for scientists. The current research work investigates the weldability of NiTi wires using Laser spot welding. The microhardness and the tensile strength of the weld joint are acquired according to Taguchi's design of experiment. The significance of the control factors (laser power, scan speed, and focal length) is identified through ANOVA, and an ideal factor setting for optimum individual responses is established. Moreover, simultaneous optimisation of multi-performance characteristics is also attempted through Grey Relational Analysis (GRA) method. From the GRA, 300 W laser power, 1 mm/sec scan speed, and 0.5 mm focal position are found to be giving optimum results for both the responses. The result from the confirmation runs showed that the predicted optimal welding parameters improve the individual as well as the multiple performance characteristics. [ABSTRACT FROM AUTHOR]