Microstructural Investigation of Ti Coating on Ti6al4v by Laser Cladding

Understanding the effect of processing parameters is vital in controlling the properties of the final product fabricated from the laser cladding process. The objective of the paper is to characterize the influence of laser scanning speed of laser cladding of commercially pure titanium powder on Ti6Al4V at different scanning speeds. The results obtained showed that the clad height, width and porosity generally reduce as the scanning speed increases. The microstructure of the clad zone is of Widmanstatten structure in nature, the heat affected zone is acicular martensitic in nature, indicating a single beta phase, resulting from the temperature at this zone exceeding the critical point of the Ti6Al4V alloy substrate. The formation of titanium alloys was observed in the cladding zone, with a rich Ti phase. The deposited Ti powder reacts with both Al and V from the substrate, resulting from high affinity of Ti for both Al and V and diffusion of these elements from the substrate into the molten powder during laser cladding process. The average hardness was found to increase with an increase in scanning speed for all samples investigated, with the microhardness at the coatings is lower than that of the substrate material.