Deformation behavior during hot processing of the alloy of the Al-Mg system economically doped with scandium

摘要

Hot deformation behavior of the new alloy 1580 sparingly doped with scandium (Al-5Mg-0.6Mn-0.10Sc-0.11Zr) was studied under the deformation temperature ranging from 350 to 450 degrees C and strain rate ranging from 0.01 to 10 s(-1). Hot deformation by uniaxial compression and torsion was carried out on a Gleeble 3800 thermomechanical simulator. Hot deformation of the alloy 1580 is accompanied by dynamic softening with the establishment of a balance between the rates of nucleation and annihilation of dislocations. Alloy flow stresses increase with increasing strain rate and decreasing temperature. The experimental results for the new alloy are in full agreement with the known concepts that the combined effect of temperature and strain rate on the deformation behavior of metallic materials is described by the Zener-Hollomon parameter. The deformation activation energy of the alloy obtained by the regression analysis of steady-state flow stresses is 175.7 kJ/mol. When using the steady-state flow stresses normalized to the shear modulus, the deformation activation energy is 148.8 kJ/mol and is close to the activation energy of self-diffusion of aluminum. Analytical expressions are obtained for steady-state flow stresses as a function of the Zener-Hollomon parameter, which make it possible to predict the deformation resistance of the alloy 1580 in a wide range of temperatures and strain rates. This result is important for FEM modeling and for the choice of temperature and stain rate of hot deformation of the alloy under study. Comparison with the literature data showed that in the region of high temperatures and low strain rates, the flow stresses are weakly dependent on the scandium content in the alloy. However, with a decrease in the temperature and an increase in the strain rate, an increase in the scandium content in the alloys leads to a noticeable increase in the flow stresses. In torsion tests, a sharp increase in the ductility of the alloy is observed at a temperature of about 400 degrees C. One of its probable causes may be dissolution of particles Al-3(Sc,Zr) during hot deformation in this high-temperature region.