Microstructure and mechanical properties of sandwich copper/steel composites produced by explosive welding

The explosive welding process is widely used for fabrication of layered composites. However, many problems connected with microstructure formation near the interface during explosive loading and the dependence of composites final properties from fabrication technique and subsequent treatment are unclear. In the present work, we researched feature of interface structure, microstructure and mechanical properties of sandwich composites on base of copper and low carbon steel joined by the explosive welding. Three-layered copper/steel/copper composites have wavy interfaces which were caused by the effect of plates impact collision. Cold rolling was used as additional hardening process of a welded sandwich composites. It was found that wavy interface after cold rolling acquires a waveless profile. According to EBSD analysis, explosive welding and cold rolling with a total reduction of 50% resulted in grain refinement in copper and steel layers due to the development of dynamic polygonization and recrystallization processes. From the results of tensile tests, it was determined that the sandwich composites have higher strength properties as compared to initial copper in 1.8–3.5 times. The high values of impact strength of sandwich composites are attributed to the influence on ductile copper layers and fracture energy dissipation at the expense of crack deviation while crossing the interfaces.