Influence of Rolling and Annealing Modes on Properties of Sheet Semifinished Products Made of Wrought Aluminum Alloy 1580

Abstract

This article analyzes the processability and properties of sheet products made of a large grade 1580 alloy ingot with a lower scandium content in the range of its specifications. The processability of the ingot upon hot and cold rolling are estimated and the influence of percent reduction and annealing modes on properties of cold-rolled semifinished products from the alloy under consideration are analyzed. The experiments are performed with a commercial large ingot with a cross section of 500 × 2100 mm made of 1580 alloy with scandium content of 0.067 wt %. The experimental procedure is comprised of several steps of rolling and thermal treatment of sheet semifinished products at various stages of the developed mode of metal deformation and tests of mechanical properties of the respective samples using an LFM 400 kN universal testing machine. In order to perform experiments, a template with the sizes of 60 × 500 × 900 mm is cut out of the ingot and then billets for rolling are produced with sizes of 50 × 180 × 300 mm, which are exposed to homogenized two-stage annealing predeveloped for this alloy. As a consequence of the hot rolling of annealed billets at 450°C and the cumulative percent reduction of e∑ = 84–90%, sheet semifinished products are obtained with a thickness of 5–8 mm. Then, after their annealing at t = 320°C for 6 h, by means of cold rolling, thin semifinished sheets with a thickness from 2 to 6 mm are produced. Their mechanical properties in deformed and annealed states are analyzed, demonstrating that, upon cold rolling to e∑ = 38%, the strength properties of 1580 alloy increase to σ0.2 = 380 MPa; then, the growth intensity decelerates and, at e∑ = 60%, this variable is 400 MPa. The influence of annealing at t = 250–350°C on the mechanical properties of sheet semifinished products is also analyzed. It is detected that it decreases the strength properties and increases plasticity; the maximum offset yield stress corresponds to the annealing temperature of 250–275° at sufficiently high plasticity. It is established that, in terms of the strength properties, the sheet semifinished products made of 1580 alloy with lower scandium content are superior to those made of similar AW-5083 (United States) alloy without the addition of scandium by 10–15%, and the plasticity properties are 40–60% higher.