Explosive welding of hollow-channel SUS304/Q235 bimetallic plates using compacted Fe-Sn powder mixture: functionally graded design and mechanism study

Dissimilar metal hollow components are critical for aerospace and energy applications, but conventional explosive welding faces issues: flow channel collapse, weak interfacial bonding, and filler retention. This study proposes a groundbreaking solution using Fe-Sn functionally graded materials as filler, achieving synergistic optimization of localized high-strength support and low-temperature softening via controlled Fe/Sn volume ratios. Focused on explosive welding of SUS304/Q235 hollow flow channels, it investigates dynamic welding responses under varying Fe/Sn volume ratios through coupled ALE and SPH simulations, with experiments using parameters optimized through these simulations. It was found that increasing Fe content in filler improves uniformity of maximum and minimum pressures on the base plate, but the improvement slows down significantly when Fe content reaches a certain level. Considering filler extractability, an Fe-Sn ratio of 3:4 was determined as optimal formulation. The experiments produced samples with hardly any channel deformation and superior welding interface waveforms, confirming technical superiority of our approach. SPH simulations further elucidate the interface wave formation mechanism. It can be described as a result of the interaction of jetting and protrusions. This study pioneered a functionally graded filler design, successfully resolving geometric stability and interfacial integrity challenges in the explosion welding of thin-walled hollow components.