Abnormal interfacial bonding mechanisms of multi-material additive-manufactured tungsten–stainless steel sandwich structure

Abstract Tungsten (W) and stainless steel (SS) are well known for the high melting point good corrosion resistance respectively. Bimetallic W–SS structures would offer potential applications in extreme environments. In this study, a SS?W?SS sandwich structure is fabricated via special laser powder bed fusion (LPBF) method based on an ultrasonic-assisted deposition mechanism. Material characterization of SS?W interface W?SS was conducted, including microstructure, element distribution, phase nano-hardness. A coupled modelling method, combining computational fluid dynamics with discrete simulated melt pool solidification at material interfaces. The study shows that bonding (SS printed W) combined effect solid-state diffusion different elemental rates grain boundary diffusion. keyhole mode (W SS) makes pre-printed SS layers repeatedly remelted, causing liquid W to flow into sub-surface through cavities realizing interface. above interfacial behaviours significantly from previously reported mechanism convection during multiple LPBF. abnormal first time.