International Journal of Lightweight Materials and Manufacture (Mar 2023)
Study the influence of scandium content and annealing regimes on the properties of alloys 1580 and 1581
Abstract
The effect of scandium content and annealing regimes on the properties of cold-rolled sheets from 1580 to 1581 alloys has been studied. The relevance of research is caused by the need to reduce the cost of alloys of the Al–Mg system with the addition of Sc by reducing the concentration of this element in them without a significant decrease in strength. The initial workpieces for research were ingots of three compositions of alloy 1580 with scandium content from 0.05 to 0.1% (wt.), an ingot of alloy 1581 with 0.03% (wt.) scandium, as well as an ingot of alloy 5083, which is an analogue of alloys 1580 and 1581, but without scandium. Ingots with a cross section of 60 × 200 mm were obtained on a physical model of a semi-continuous casting unit (SCCU) in the laboratory of the Siberian Federal University. Then, according to the regime obtained at the semi-continuous casting unit, a large-sized ingot with a cross section of 560 mm × 1310 mm was cast under industrial conditions. Ingots of the same size 40 mm × 120 mm × 170 mm were cut from laboratory and industrial ingots, and annealed according to a two-stage regime: the first heating at 350 °C, 3 h, the second heating at 425 °C, 4 h, and subjected to hot rolling with heating up to 450 °C to thickness 5 mm. Then the strips were annealed at 380 °C for 1 h, rolled at room temperature to a thickness of 3 mm, and annealed at temperatures of 250, 275, 300, and 350 °C. Tensile tests of samples made from sheets of 1580 and 1581 alloys after annealing in the temperature range of 250–300 °C showed that they surpass alloy 5083 in strength properties by no less than 10%. Studies of the cast and deformed structure of alloys 1580 and 1581, carried out by the methods of light, scanning and transmission electron microscopy revealed that during annealing dispersed particles of the Al3(Sc, Zr) phase precipitate from the solid solution of ingots, which, during deformation of the alloys and subsequent technological heating associated with hot rolling and annealing, contribute to the formation and preservation of a subgrain structure in sheet semi-finished products. This factor prevents the occurrence of recrystallization and ensures the strengthening of deformed semi-finished products.
