Microstructure and mechanical property of bonding zones between Ta foil and steel plate fabricated by explosive welding
(National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing 210094, China)
Abstract: This work aims to produce a thorough comprehension concerning microstructure related properties of the joint interface between Ta foil and steel plate fabricated by explosive welding. For this, a self-developed explosive welding configuration was employed to join Ta foil and steel plate, and different microscopic methods were adopted to investigate its microstructures and mechanical properties. It was found that the Ta/Fe interface was featured by regular wavy structures with a well-defined amplitude and period. The melted zones were mainly observed within the vortex structures, and occasionally at the Ta/Fe interfaces, which were formed by intense mixing of participating metals. The EBSD analyses revealed a diversity of the grain structures near the Ta/Fe interface, such as formation of the curved and elongated grains in Ta matrix, and fine equiaxed and columnar grains in Fe matrix. Especially, several adiabatic shear bands (ASBs) characterized by small equiaxed grains were found in Fe matrix, which were due to stress wave concentration in the narrow paths, and the materials in these zones underwent a recrystallization process. Finally, the nanoindentation results revealed inhomogenous mechanical behaviors in the bonding zones, which could be well related to the changes of microstructure and chemical composition.
Key words: explosive welding; tantalum coating; adiabatic shear band; nanoindentation