Laser welding of NiTi shape memory sheets using a diode laser

Abstract NiTi shape memory alloy (SMA) are widely applied in many industrial domains, such as biomedical, aerospace, automotive and power plants, due to its outstanding functionality including superelasticity (SE) and shape memory effect (SME). The machining process of this material is challenging with a lot of barriers. Accordingly, joining techniques can be an alternative approach to design the shape memory components with more flexibility. Among all methods, laser welding process is a reliable and economical technique for joining of NiTi alloys. However, thermal process influences strongly on the strength and functionality of the NiTi welded joints in the Heat Affected Zone (HAZ) and the Fusion Zone (FZ). Indeed, the transformation temperature of NiTi alloy can be altered due to varying in the material composition. Therefore, controlling of the operational parameters, including laser power, scan speed or focal distance lead to an effective improvement in the mechanical and the functional behavior of NiTi joints. It consequently enhances the weldability of this material. This current study investigates the laser welding of NiTi thin sheets with a High-Power Diode Laser (HPDL) and reports microstructural, functionality, and mechanical effects of the process in following.