Effect of the Speed Asymmetry on Technological Plasticity of the Aluminum-Magnesium-Scandium System Alloy During Rolling

Problem Statement (Relevance). Aluminum nonheat-treatable alloys of the aluminum-magnesium-scandium system are characterized by good weldability, high mechanical properties, relatively low density, and the absence of strengthening heat treatment (such as quenching and aging). However, the high cost of these alloys hinders their use in various industries. Therefore, it is necessary to develop processing methods that can increase the yield of the finished product with the expensive Al-2%Sc masteralloy. However, due to the low technological plasticity of 5XXX series aluminum alloys, edge cracking of sheets or strips occurs during hot rolling, which requires increasing the fractional deformation. This, in turn, affects the final cost of the semi-finished hot-rolled product. Accordingly, studying changes in the technological plasticity of 5XXX series aluminum alloys during rolling is relevant. Objectives. The work is aimed at determining the parameters of the asymmetric rolling process, in particular the rolls speed ratio, during processing the 5XXX series aluminum alloy with scandium, ensuring an increase in the technological plasticity of the material while reducing the force during hot rolling maintaining the level of mechanical properties after cold rolling. Methods Applied. Hot and cold rolling were carried out on a unique industrial and laboratory mill DUO 400 of the Zhilyaev Laboratory of Mechanics of Gradient Nanomaterials of the NMSTU. The forces arising during rolling were recorded by the software of the DUO 400 mill. The quality of the obtained semi-finished rolled products was assessed in accordance with GOST R 57510-2017. Surface hardness was determined by the Brinell method in accordance with GOST 9012-59. Mechanical properties were assessed in accordance with the ASTM E8 standard. Results. At the rolls speed ratio V1/V2 in the range of 1.1-1.3, no defects were observed during hot rolling. The rolling force decreased from 1400 kN to 1280 kN. The technological plasticity increased, as evidenced by the decreased probability of edge cracking with an increase in the percent reduction during hot rolling. The values of mechanical properties after cold rolling (sv, s0.2, d) varied within the range of 421-464 MPa for ultimate strength sv, 373-416 MPa for yield strength s0.2, and 2-7% for relative elongation d. Practical Relevance. Asymmetric rolling affects the change in the technological plasticity of 5XXX series aluminum alloy with the expensive Al-2%Sc masteralloy. As a result, the number of passes during finish hot rolling can be reduced (to one). This eliminates additional edge cooling and cracking, and also has a positive effect on the cost of semi-finished hot-rolled products and their production time.