Study on the formation of anfractuous interlocking interface in laser shock of molten pool

Abstract

A method utilizing dual molten pool and laser shock in hybrid additive manufacturing was employed to form an anfractuous interlocking interface, thereby enhancing the joining performance of dissimilar metals. Leveraging on the substantial difference in melting points between the two metals, the Ti6Al4V wire (melting point ~1668 °C) was partially melted using a continuous wave laser in directed energy deposition technology, while the aluminum alloy substrate (melting point ~635 °C) underwent partial melting via heat conduction. This process resulted in the creation of a dual molten pool area comprising liquid wire, solid wire, and liquid substrate. Additionally, applying a laser shock simultaneously inducing oscillation and promoting heat transfer within molten pool. This process effectively eliminated pore defects and facilitated the formation of an anfractuous interlocking interface. The molten pool and anfractuous interlocking interface were evaluated under varying laser shock energies. At 2 J, the joint strength of the AlTi achieved 422.6 MPa, with a number of pore defects decreasing by approximately 63.23 % and microhardness increasing by 9.20 %. Furthermore, this method has enlightening significance for the joining of dissimilar materials and serves as a valuable reference for dissimilar welding, providing a new technology for laser additive manufacturing.