Zonal differences in deformation characteristics of AZ31 Mg alloy constrained by heterogeneous metals

Abstract

Under the temperature range of 200–400 °C and the strain rate of 0.01~1s−1, the microstructure evolution of AZ31B Mg alloy under the new hot constrained compression method compared with single compression test was studied by means of uniaxial compression test and finite element simulation. The effects of strain rate, temperature and constraining material on the equivalent stress and strain, damage distribution, and deformation zone structure of AZ31B Mg alloy are discussed. Results show that, compared with single compression, the stress state and deformation degree of each zone of the specimen is different under the hot constrained compression method. The specimen with constrained compression produces a special deformation zone. Under the condition of constrained compression deformation with the same strain rate and temperature, the degree of structural deformation in each zone has a strong correlation with the ductility of the constrained material. In the macroscopic characteristics of each zone, this correlation is manifested as the increase of equivalent stress and strain, the decrease of the high damage value zone and the disappearance of shear cracking phenomenon. The high damage area at 200 °C has been reduced from 80% to 40%. In the microstructure characteristics of each zone, this correlation is also manifested in the increase of twins and recrystallized grains, and the enhancement of the uniformity of the structure. When the strain increases from 0.2 to 0.7 at 200°C-1s−1, the AZ31B Mg alloy in the HCC-Cu obtains a more uniform grain size distribution and the elongation to fracture increases from 0.22 to 0.56.

Keywords

• AZ31B Mg alloy
• Hot-deformation behavior
• Microstructure
• Damage
• Cracking