Hot deformation behavior, microstructure evolution and slip system of Mg-2Zn-0.5Mn-0.2Ca alloy

Abstract

The hot deformation behavior of as-cast Mg-2Zn-0.5Mn-0.2Ca alloys was investigated by hot compression tests conducted at 250–400 °C with strain rates of 0.001–1 s−1. The true stress–strain curves showed that flow stress increased with the increase of strain rates and decrease of temperatures. The constitutive equation was obtained, and the calculated average activation energy is 196.79 kJ mol−1. The processing map is developed. Combined with the analyses of microstructural and processing map, the optimal processing parameter is determined at 350 °C and 0.001–0.1 s−1. Based on EBSD analysis, the microstructures of the instability areas and the stable areas are quite different, yet both have a //CD texture. The slip system in deformed grains was determined by the in-grain misorientation axis (IGMA) analysis. Typical discontinuous dynamic recrystallization (DDRX) mechanism is the main dynamic recrystallization (DRX) mechanism. As the decrease of the strain rates and the increase of the deformation temperatures, the DRX fraction gradually increased, meanwhile, the behavior of DRX has an obvious weakening effect on texture strength.

Keywords

• Hot deformation behavior
• Constitutive equation
• Processing map
• Microstructure evolution
• Dynamic recrystallization
• Slip system