Explosive welding

Abstract

Explosive welding, which is a solid-phase welding process, was probably discovered by chance by Philipchuk, who states that he first observed the effect when explosively forming an aluminium U-channel on a steel die. It was found that the U-channel could not be removed from the die because a circular-shaped area had become welded to the die. From more recent work it would appear that an excessive explosive charge must have been used in this forming exercise to have achieved the impact velocity required for welding. Allen, Mapes, and Wilson carried out experiments concerned with the impact of right cylindrical bullets fired at thin targets and they noted a rippling of the surface of the bullet. Abrahamson, who was concerned with the rippling or wave action, continued the work of Allen et al. and observed, when firing a steel bullet against an oblique copper target, that adhesion occurred between the steel and the copper; he shows a photomicrograph of the wavy interface typical of explosive welding. This, of course, leads to the conclusion that explosive welding is associated with the oblique impact between the two surfaces to be welded. Crossland and Bahrani also noted that it was well known during the First World War that a bullet or shrapnel could stick to metal surfaces which they impacted, though it was not appreciated that this could be the basis of a welding process.