Microstructural evolution, flow stress and constitutive modeling of Al-1.88Mg-0.18Sc-0.084Er alloy during hot compression
(1. School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China;
2. Key Laboratory of Lightweight Structural Materials of Liaoning Province, Northeastern University, Shenyang 110819, China;
3. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China;
4. Wuhu Cowin Automobile Co., Ltd., Wuhu 241000, China;
5. Institute of Materials Processing and Forming Technology, Guangdong General Research Institute of Industrial Technology, Guangzhou 510650, China)
2. Key Laboratory of Lightweight Structural Materials of Liaoning Province, Northeastern University, Shenyang 110819, China;
3. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China;
4. Wuhu Cowin Automobile Co., Ltd., Wuhu 241000, China;
5. Institute of Materials Processing and Forming Technology, Guangdong General Research Institute of Industrial Technology, Guangzhou 510650, China)
Abstract: To explore the hot compression behavior and microstructural evolution, fine-grained Al-1.88Mg-0.18Sc- 0.084Er (wt.%) aluminum alloy wires were fabricated with Castex (continuous casting-extrusion) and ECAP-Conform, and their hot compression behavior was investigated at temperatures of 673-793 K and strain rates of 0.001-10 s-1; the microstructures were characterized by optical microscope, X-ray diffractometer, transmission electron microscope, and electron backscattered diffractometer, and the flow stresses were obtained by thermal compression simulator. Microstructural evolution and flow curves reveal that dynamic recovery is the dominant softening mechanism. Continuous dynamic recrystallization followed by dynamic grain growth takes place at a temperature of 773 K and a strain rate of 0.001 s-1; the yielding drop phenomenon was discovered. Hyperbolic sine constitutive equation incorporating dislocation variables was presented, and a power law constitutive equation was established. The stress exponent is 3.262, and the activation energy for deformation is 154.465 kJ/mol, indicating that dislocation viscous glide is the dominant deformation mechanism.
Key words: Al-Mg alloy; ECAP-Conform; hot compression; microstructure; flow stress; constitutive equation