Microstructure of explosively bonded composites, low carbon-steel to low carbon-steel and austenitic stainless steel to low carbon-steel, has been investigated by transmission electron microscopy. The bond zone whose width is less than several μ consists of a mixture of a clad metal and a base metal, and the small crystal grains in each component metal are several thousand Å in size. Both areas within about 10 μ from the bond zone are composed of either small crystal grains or elongated grains of several thousand Å width. Dislocation density in these areas as well as the bond zone is of the order of 10⁹/cm². Larger crystal grains at distance of 10-600 μ from the bond zone has a dislocation density of 10¹⁰-10¹¹/cm², and the dislocation density at further increased distance is 10⁹-10¹⁰/cm². There exist tangled dislocations with cusps, dislocation loops and undeveloped cell structure. Thin deformation twins in austenitic stainless steel and elongated subgrains resulting from α→ε→α transformation of low carbon-steel are observed profusely. No significant hcp ε-phase is detected in the stainless steel.
The adequacy of the proposed mechanism of the explosive bonding based on the theory of compressible fluid is discussed from the result obtained.