Kazuyuki Hokamoto

Improvement of bond strength of Al/Cu transition joints made by a single‐shot explosive welding technique using a Cu intermediate plate

Summary This paper describes efforts to fabricate explosively welded Al/Cu clad through insertion of a Cu intermediate plate between the Al driver and Cu base plates. In explosively welded Al/Cu clad fabricated by the conventional method, generation of an excess reacted interfacial zone causes degradation of bonding properties. Application of a Cu intermediate plate is effective as a means of reducing the energy dissipated by collision. The effect of the kinetic energy lost by collision on the thickness of the reacted interfacial zone and on the bond strength are examined in experiments with stainless steel. Efforts are made to fabricate Al/Cu conductive transition joints of commercial size with a Cu intermediate plate. The bonding properties obtained are better than those obtained by the conventional method.

Single-shot explosive welding of hard-to-weld a5083/sus304 clad using sus304 intermediate plate

A5083/SUS304 is known as a very difficult combination to weld by an explosive welding technique. This combination is tried to be explosively welded using thin SUS304 intermediate plate. The formation of thick interfacial zone at welded interface disturbs the bonding between the interface and the microstructure of this interfacial zone is composed of Al and Fe4Al13. Separation is generated at SUS304/interfacial zone or inside the interfacial zone. The position of the separation fabricated by explosive welding is different with it fabricated by the other method which uses heat treatment. Since the thick interfacial zone is formed by excess energy at the interface, to insert thin SUS304 plate is effective as to decrease the energy dissipated by the collision between plates. Moderate collision velocity is also required for good bonding to generate the metal jet. Welding window is constructed by the parameters of kinetic energy loss by collision (ΔKE) and collision velocity (Vp), and the weldable range of this combination is Vp =350-670m/s and ΔKE=1×105-5.5×105J/m2.

Study of forming of magnesium alloy by explosive energy

Magnesium alloy is an attractive next generation material due to its high specific strength with low weight. However, magnesium alloys has few slip lines with close‐packed hexagonal lattice, and generally poor ductility at room temperature, therefore it is difficult to form this material by cold forging. It is well known that the speed of deformation of metallic materials rapidly changes at the high strain rate. For some metallic materials, it is reported that the ductility also increases at the high strain rate with this speed effect. In this study, a series of high speed impulsive compressive tests were carried. By using explosives for shock wave loading, the velocity in this experiment reached 100 m/s that can’t be easily obtained in normal experiment. In this paper, the possibility of forming the AZ31 extrusion magnesium alloy using explosive‐impulsive pressure is investigated. And improved ductility by the effect of high‐rate deformation is observed with this alloy.