Investigation of surface modification of Al alloy by laser-TIG hybrid melt injection WC powder

In order to overcome the difficulties of laser melt injection (LMI) on aluminium alloys, including high reflection of laser, oxide film and high heat conductivity, laser-tungsten inert gas (TIG) hybrid melt injection was exploited. The influence of process parameters, including the mode of hybrid laser-TIG, feeding powder type, the carrier gas flow, the shield gas flow of TIG, laser power and TIG current, were investigated. The results show that, in order to achieve appropriate surface enhancement effect, the powder should be fed from back side of laser beam. With the increase of TIG current, the depth of LMI layer increases monotonously. With the increase of laser power, the depth of LMI layer increases firstly and then decreases. The carrier gas flow and gas flow of TIG are the key factors which influence the LMI process, and should be matched and selected. Through optimization of process parameters, WCp/Al layer was prepared successfully on the surface of aluminium and the LMI layer with different thickness ranging from 0.5 to 4.3 mm can be achieved.