In this research, the effect of stand-off distance on the interfacial mechanical and metallurgical properties of explosively bonded 321 austenitic stainless steel to 1230 aluminum alloy tubes was investigated. Interfacial microstructure was evaluated by optical microscopy and scanning electron microscope. Also, Microhardness tests were also carried out. The results show that with increasing of stand-off distance from 1 mm to 2.5 mm, thickness of intermetallic compounds at the interface increased from 3.5 µm to 102.3 µm, and also shape of interface was transited from smooth to wavy. The microhardness of the sample with 1 mm stand-off distance was 650 HV that increased to 927 HV in the sample with 2.5 mm stand-off distance which is related to intermetallic amount. The proportional amount of strength were 103.2 MPa and 214.5 MPa in the above samples respectively.

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In the current investigation, corrosion behavior and microstructural variations of explosion-welded joint of bronze-carbon steel dual-layer plates were studied. The resultant curves of potentiodynamic's polarization tests demonstrated that the lowest corrosion rate was related to the sample with maximum explosive load thickness, and the highest corrosion speed was for the sample with minimum standoff distance. EIS test results of welded samples were indicative of creating a passive layer at the beginning of immersion process which showed that the polarization resistance has been reduced by increasing of explosive load thickness. So, the corrosion mechanism included two stages; at the beginning of immersion, for the samples with the lower thickness of explosive load, a passive layer would be created around the component due to higher concentration gradient and then, by removing of this layer, the galvanic couple determines the corrosion rate.

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In this research, the effects of heat treatment are studied on the microstructure and mechanical properties of the explosive bonding of 304 stainless steel plates and CK45 carbon steel with a constant explosive load and various standoff distances. The samples are heat treated in a furnace for 2-h and 4-h at 250℃ and 350℃. The results imply that by increasing the standoff distance from 4 to 5 mm, the impact kinetic energy increases and severe plastic deformation occurs in the bonding interface. The metallography results indicate the wave-vortex nature of the interface with the increase of standoff distance. In addition, heat treatment for 2 h at 350℃ leads to an increase in the thicknesses of intermetallic compounds in the interface. Also, the hardness decreases from 271 to 171 Vickers, and from 279 to 195 Vickers with 2 h of heat treatment at 350℃ in samples with standoff distances of 4 and 5 mm, respectively. Furthermore, the strengths of the samples decrease from 449 to 371 MPa, and from 510 to 433 MPa, respectively. Hardness and strength changes occur due to changes in the thickness of the intermetallic area and an increase in grain sizes.

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