Microstructural Variation at Interface during Fiber Laser Joining of NiTi/Ti6Al4V and effect of Mechanical Strength

Publication date: Available online 22 February 2020Source: Journal of Materials Processing TechnologyAuthor(s): Suman Chatterjee, Ankit Kumar Pandey, Siba Sankar Mahapatra, Kanwer Singh Arora, Ajit BeheraAbstractWelding of nitinol (NiTi) shape memory alloy (SMA) and titanium-based alloy (Ti6Al4V) finds potential application in aerospace and medical industries. However, joining of these materials poses challenging issues because material properties of each material interacts to give rise to hybrid system performance. In the present study, copper was used as an intermediate layer to restrict the formation of brittle intermetallics during welding of NiTi with Ti6Al4V using laser welding. The formation of Cu4Ti3 and CuNi2Ti complex phases attempts to minimize the formation of brittle phases like Ti2Ni. It was observed that the maximum welding strength of 353 MPa could be achieved at 800 W laser power and 17 mm/s scan speed. Physical analysis of weldments indicates the presence of pores at nano-levels (< 3.6% weld pool area) suggesting acceptable weld quality. The mechanical analysis of the weldments reveals that minimum tensile strength of the welded joint is more than the ultimate tensile strength of the weakest intermediate material (copper). The study had presents the possibility of using high melting point intermediate layer material during welding of nitinol with other materials to avoid the formation of unwanted phases.Graphical abstract
Source: Journal of Materials Processing Technology - Category: Materials Science Source Type: research