Study the Microstructural and Mechanical Behaviours
of Large Surface area Cladding of NiTi on Ti-Alloy by
TIG Surface Modification Technique

Abstract

Smooth large surface area cladding was done of NiTi on Ti-6Al-4V by using tungsten inert gas cladding method. This was possible with multilayer passing of TIG arc over the specimen. That is clad layer formed over previous clad layer by maintaining different overlapping ratio. This overlapping ratio was maintained by shifting the workpiece towards the nozzle. The melted track gave a smooth rippled surface topography and the clad surfaces were free from cracks. The surface roughness values of the samples were increased with decreased in overlapping ratio. The variations of overlapping ratio have a significant effect on the microstructure and mechanical properties of the coating. Wear resistance of the coating area increases with increase in overlapping ratio. But at higher overlapping ratio, porosity was formed. Therefore wear resistance further decreased. The hardness value of the overlapped zone of cladding was much more than substrate material and there was very less variation in hardness value between the center of clad track and at the overlapping area. For small are a cladding 52% overlapped cladding was prefered but for large surface area 36% overlapped cladding was acceptable because uniformity of clad was seen at 36% overlapped sample.