Superior ductility and strength enhancement of ZK60 magnesium sheets processed by a combination of repeated upsetting and forward extrusion

This research work is concerned with creation of ZK60 Mg sheets by various combinations of the repeated upsetting (RU) and forward extrusion (Ex) operations. The RU process was conducted with different passes and at 250°C, whereas the subsequent forward extrusion was performed at 220°C. Complementary tensile tests together with fractography, and microstructural and textural studies were carried out in order to investigate the influence of the process types and conditions on the material properties of the sheet products. It was found that combination of the RU and Ex operations could result in ductile ZK60 sheets with improved strength and strain hardening capacity. The maximum elongation was achieved after 3 passes of RU followed by Ex process. This processing route also resulted in balanced ultimate strengths in both extrusion and transverse directions with almost the highest strain hardening capacity. The effects of RU number of passes and forward extrusion process on the microstructures, textures, mechanical properties and the fracture of the ZK60 sheets were also investigated and, based on the experimental findings obtained; several important conclusions were drawn and explained in this article.