Microstructural characterization and mechanical behavior of Mg-AZ31B/Al 6063 bimetallic sheets produced by combining continuous shear deformation with direct extrusion

Abstract

To enhance the bonding effect and mechanical properties of hot-extruded Mg/Al bimetallic sheets, a novel bimetallic hot extrusion process called direct extrusion and continuous shear deformation (DECS) was proposed based on the shear deformation process. An extrusion die was designed and manufactured, and the influence of extrusion temperature on the microstructure and mechanical properties of the Mg/Al bimetallic sheet was investigated. Results showed that at an extrusion temperature of 330 ℃, defects and cracks appeared at the bonding interface, while favorable metallurgical bonding between Mg/Al bimetallic sheet was achieved at 370 ℃ and 410 ℃. The Mg layer exhibited a nearly complete dynamically recrystallized (DRXed) structure, with the average grain size increasing with higher extrusion temperature. A strong {0001} basal texture was observed in the Mg layer at 330 ℃ and 410 ℃. At 370 ℃, the combined action of shear strain between the bonding interfaces triggered the activation of multiple slip systems in the Mg layer, reducing the basal texture strength. The Al layer exhibited preferred orientations at various extrusion temperatures, particularly the multi-grain < 001 > and < 101 > orientations. The maximum shear strength of the formed sheet was determined to be 18.1 ± 3.7 MPa, with a maximum elongation of 38.4 %.