Dissimilar material welding of tantalum foil and Q235 steel plate using improved explosive welding technique

Achieving high quality tantalum coatings on common metals is still a challenging task, due to potential technical problems such as high differences in melting points and formation of intermetallic compounds. In this work, an improved explosive welding technique was successfully employed to prepare tantalum coatings on a steel substrate, where a special charging structure and a double-layer buffer structure were used to obtain an ideal welding condition. The microstructure analyses of the achieved joints were conducted using electron backscatter diffraction (EBSD), and scanning electron microscope (SEM) cooperated with energy dispersive X-ray spectroscopy (EDS) system. Tensile, three-point bending, and nanoindentation tests were carried out to investigate the mechanical properties. It was concluded that the improved explosive welding technique was a suitable method to produce Ta coatings on steel substrate. In both microstructure observation and mechanical tests, an excellent bonding quality between Ta foil and Q235 plate was confirmed. In addition, a novel vortex structure, good for preventing crack propagation from the brittle melted area, was observed at the Ta/Fe interface. Finally, the corrosion test indicated that the corrosion resistance of Q235 plate was remarkably improved after being coated by Ta foils using explosive welding.