Tensile instability and limit strain behavior of explosion-welded steel/Al plate considering interface defect characteristics

Explosion-welded steel/Al composite plate has advantages of excellent conductivity, heat conductivity, light weight, and corrosion resistance. While the elongation of explosion-welded steel/Al composite plate can not been predicted by the traditional damage fracture theory. Establishing a new prediction model to analyze the deformation behavior of steel/Al composite plate are necessary. First, the deformation behavior and interface microscopic characteristics of explosion-welded steel/Al composite plate were analyzed using uniaxial tensile tests and SEM experiments, the result showed that wave structure, brittle phase, and microcrack existed at the interface layer of composite plate, the uniform elongation and elongation of steel/Al composite plates basically deviate linearly from the mixing law. Second, simulation models were established to analyze the effect of interface wave structure, brittle phase, and interface microcracks on the instability and fracture behavior of explosion-welded steel/Al composite plate. The interface wave structure could enhance the elongation of the composite plate, while the uniform elongation of the composite plate decreased with the increasing of brittle phase and microcrack. When f0=0.985, the predicted tensile strength through simulation is 258.94 MPa, which only has a difference of 1.9 MPa from the experimental value, when the length of the crack increases from 0.03 mm to 0.2 mm, the uniform elongation of the composite plate decreases by 92.52%. Finally, M-K theory considering the characteristics of interface defects was established to predict the tensile instability behavior of steel/Al composite plates. The instability behavior of the composite plate considering interface defects could be accurately described using the modified M-K theory when the height of the interface groove of the composite plate was Δta/Δts=ha/hs and Δta+Δts=0.5mm.