Effects of Equal Channel Angular Pressing on the Microstructure and Mechanical Properties of Explosion-Welded Al-Cu Bimetallic Plates

Explosive welding technology is crucial for the production of large-area plates composed of materials with varying plastic and physical properties. Severe plastic deformation processes increase the mechanical strength of the plates by refining grains and increasing dislocation density. The aim of the research presented in this paper was to analyze the effect of Equal Channel Angular Pressing (ECAP) on the mechanical properties and microstructure of an Al/Cu (EN AW-1050/Cu-ETP) bimetallic plate produced by the explosive welding technology. The ECAP process was carried out at room temperature. The ECAP experiments consisted of 1-3 passes using a die with a channel angle of 90°. The ram speed was 40 mm/min. The study also considered various sample cutting orientations (longitudinal, transverse) and various positions of the bimetallic sample in the die entry channel. Rotating the sample by an angle of 180° between consecutive passes was also considered. To achieve the research objective, static tensile tests, Vickers hardness tests at a load of 4.9 N, and microstructural analysis of the samples using scanning electron microscopy and energy dispersive spectroscopy were carried out. It was found that each subsequent pass in the ECAP process led to a gradual, severe change in the morphology of the Al/Cu interfacial transition layer. The orientation of the cutting plane of the samples was shown to have no effect on the hardness of the bimetallic material. Vickers hardness tests preceded by the ECAP process revealed a more uniform hardness distribution compared to the base material. The orientation of the Al/Cu plate layers in the ECAP die channel clearly influenced the character of the hardness distribution.