Effect of radial shear rolling on grain refinement and mechanical properties of the Al-Mg-Sc alloy

A method of obtaining bars from the Al-Mg-Sc alloy by radial-shear rolling (RSR) and its effect on the microstructure and mechanical properties were discussed. After RSR at different temperatures (400, 300, 250 degrees C), a gradient microstructure forms over the cross-section of the bars. From the surface to the half of radius, initial microstructure transform to an ultrafine-grained dynamically recrystallized structure with equiaxed grains (0.5 to 2 mu m) and a well-developed high angle grain boundaries net. Near the center of the bars, a deformed fiber structure of grains with well-developed low angle grain boundaries and an average subgrain size of 5 mu m was obtained. The alloy structure has a deep hierarchical arrangement characterized by the existence of submicron size particles and 10-20 nm sized Al3(Zr,Sc) nanoparticles. The mechanical properties (ultimate tensile strength 436 MPa, yield strength 350 MPa) are superior to those of almost all studied deformation methods for this alloy.