The role of scanning velocity on laser cladding of NiTi alloy onto stainless steel 316L substrate

In this research, Ni50.8Ti49.2 pre-alloyed powder was used to produce NiTi shape memory alloy coating onto stainless steel 316L substrate. Micro direct metal deposition (μDMD) process was employed to produce coatings with the thickness of 200 μm. To investigate the effect of scanning velocity and the capability of the process, three different coatings were fabricated with three scanning velocities. The effects of scanning velocity variations were investigated by scanning electron microscopy and X-ray diffraction. The results revealed that a good and precise coating can be fabricated when the scanning velocity and the laser power are 200 mm/min and 25 W, respectively, while with the scanning velocity of 120 mm/min, crack formation is inevitable, and with the scanning velocity of 150 mm/min, it would be difficult to achieve a coating with accurate thickness of 200 μm.