Micro-structure and mechanical properties of explosively welded steel/Cu pipes and Al/Cu pipe/rod via the Russian-dolls-like experimental arrangement

The steel-Q235/copper-T2 pipes and aluminum-1060/copper-T2 composite pipe/rod are fabricated by an unique manufacturing process which we call it “the Russian-dolls-like experimental arrangement”. After the experiment, samples’ welding quality along the detonation direction is firstly evaluated by an optical microscope and a scanning electron microscope equipped with a backscattered electrons detector. Mechanical properties of welded samples are checked via longitudinal compression tests. Results show that due to the jet produced by part no. 6, there is a ϕ 3.0 mm spherical groove on top of the Al/Cu explosively-welded rod. Because of this, the section 8.5 mm from the top (Al/Cu couple) is not welded, while the Steel/Cu couple is not affected. Bonding interfaces of Steel/Cu and Steel/Cu couples both change from unstable ones to regular/wavy ones along the detonation direction. Atomic ratios of steel and copper around the Steel/Cu interface varies from 44∶56 to 72∶28, and AlCu and Al₂Cu are identified around the Al/Cu interface via EDS analysis. Samples’ yield strength/strain in longitudinal compression for steel/Cu and Al/Cu couples are 598 MPa/5.8% and 340 MPa/4.8%, respectively.