Microstructure and mechanical properties of heterogeneous-gradient composite plates with a sphere-array interlayer prepared using explosive welding

Composite structures with high strength and controllable fragments driven by implosions are valuable in weaponry. This study explored a technical approach to preparing heterogeneous-gradient composite plates with a sphere-array interlayer using explosive welding. TA1 and Q235B steel plates with various spherical grooves were employed as the flyer and base plates, respectively. The spherical grooves were filled with Q235 steel balls. Composite plates were formed by a single explosion using the parallel method, and the parameters adopted in the experiment were within a weldable window. The performance of the TA1/Q235 steel balls/Q235B composite plate was studied through microstructural observations and mechanical property testing. The results indicated that the two embedded spherical structure schemes (with steel balls protruding or not protruding from the plane of the base plate) created effective metallurgical bonding interfaces between the two plates and at the top of the spheres. Surface flatness plays a crucial role in forming wavy interfaces. The composite plates embedded with non-protruding spheres exhibited better mechanical properties, higher interface strength, and a more regular, wavy interface than those embedded with protruding spheres. The ultimate tensile strength of the composite plate containing a sphere with a diameter of 2 mm was similar to that of an intact composite plate. The fracture surfaces of the specimens embedded with spheres exhibited ductile and quasi-cleavage fracturing in the tensile and impact-toughness tests. The structure of the composite plates embedded with non-protruding spheres provides a strategy for preparing multifunctional warhead shells.