The mechanics of wave formation in explosive welding

Abstract

Strong bonds can be produced by the explosive welding process and usually the weld interface has a characteristic wavy form. In this paper the mechanism of explosive welding is discussed, the present theories of wave formation are critically examined and a new mechanism of wave formation is proposed. According to this mechanism the materials of the impacting plates in the region of collision behave in a similar manner to liquids of low viscosity. As a result the impacting or flyer plate divides into a re-entrant jet and a salient jet. Very high pressure is produced at the stagnation point of the divided jet. The parent plate deforms under the stagnation point and consequently a hump is formed in the parent plate ahead of the point of collision. The hump builds up and eventually traps the re-entrant jet. The stagnation point then transfers to the top of the hump and then descends it and starts forming a new hump, and in this manner successive waves are formed. The proposed mechanism of wave formation seems to explain the experimentally observed behaviour reasonably well. Furthermore, experiments are reported in which one of the surfaces to be bonded was copper plated and the second surface was nickel plated and by this means the movements of the surfaces being bonded were traced. These experiments gave strong support to the proposed theory of wave formation.

Numerical simulation of explosive welding using Smoothed Particle Hydrodynamics method

“…After collision, an interfacial wave is generated at the bonding interface. Compared with the mechanisms of wave formation [18][19][20][21], our results are in accordance with the mechanism proposed by Bahrani et al [18].…”

Analysis of Explosively Welded Aluminum–AZ31 Magnesium Alloy Joints

“…This theorem predicts the formation of eddies for the Reynolds numbers beyond R T . The formation of the observed vortices in the present experiments could be well interpreted based on the re-entrant jet indentation mechanism, a qualitative postulate due to Bahrani et al, 13) in which, the blocking of the re-entrant jet under the trunk of the hump, formed in the base plate, leads to development of a vortex. Figure 3 demonstrates that the trapped jet comprises thin surface layers, around 40 and 20 mm thick, of flyer plate A1100 and base plate AZ31 respectively, have been swept and swirled behind the adjacent wave in the background of A1100.…”

Interfacial Morphology of Magnetic Pulse Welded Aluminum/Aluminum and Copper/Copper Lap Joints

“…Similar interfacial morphology was reported for the explosive welded joint, in which a flat flyer plate and a semicylindrical parent plate were welded. [20][21][22] Bahrani examined the influence of the collision angle on the explosive welded interface morphology using this so-called ''semi-cylinder method''. 20) It was demonstrated that no welding occurred where the collision angle was in the range from 0 to 6 , but welding with wavy morphology was achieved at angles in the range from 6 to 33 .…”