An inclusive comparative study on the influences of the ring rolling process at elevated temperatures on the mechanical properties and microstructures of two centrifugally cast light alloys

High-performance seamless rings made from different alloys have widely been used in various applications. This study compares the effects of the radial–axial ring rolling (RARR) process at elevated temperatures on the mechanical properties of centrifugally cast Al6063 aluminum and AM60 magnesium rings. The cast rings of these two alloys were ring rolled at three temperatures of 200, 250, and 300 °C and three roll rotational speeds of 40, 60, and 80 rpm. The yield stress, ultimate strength and fracture strain of the cast and rolled Al and Mg rings were measured for different directions, namely, rolling direction (RD), transverse direction (TD), and normal direction (ND), as determined by their hardness and the average grain size (AGS). The grain sizes of both the materials after the RARR process were smaller than the cent-cast ones. Moreover, the higher the temperature and/or the main roll rotational speed, the greater the AGS and the lower the yield stress, ultimate strength and hardness of the finally rolled ring. Nevertheless, the AGS of the AM60 samples was much larger than the related Al6063 rings in all the experiments. The ultimate strength, fracture strain and toughness of the Al rolled rings were also larger than the similarly deformed Mg samples, although the specific strength of the latter was much superior to the former. The deformed Mg rings characterized a more isotropic behavior compared to the Al specimens. The effects of the process temperature on the strain-hardening behaviors of these two alloys were also dissimilar. The numerical simulations of the RARR process also illustrated that the maximum, moderate, and minimum equivalent strains in the radial direction were created at the outer, inner, and middle regions, respectively, of the deformed ring, which is in agreement with the experimental findings for the AGSes at these areas.