| Popis: |
A physical model of a semi-continuous casting unit (SCCU) has been manufactured and tested, designed to develop a technology for casting flat and cylindrical ingots from experimental aluminum alloys for subsequent metal forming. The SCCU includes two induction melting furnaces with a tilting mechanism, a rotary mixer, a metal path system, a vertical casting machine, a jib crane, water supply, power supply, monitoring and control systems. SCCU testing was carried out on six heats of alloy 1580 of the Al-Mg system with the addition of scandium. In the first three ingots the scandium content was 0.05% (wt.). In the second series of three heats ingots with 0.075% (wt.) scandium were cast. The ingots had a high surface quality, did not have casting defects, and there were no inclusions of primary intermetallic compounds Al3(Sc, Zr) in the structure of the ingots. The bottom and runner parts of the ingots were cut off, all faces were milled and subjected to homogenization annealing in a two-stage mode: the first heating at 350 °C, 3 h, the second heating for 1 h to 425 °C, 4 h. Then the billets were hot rolled from 40 to 5 mm, annealed at 380 °C, 1 h, rolled at room temperature to a thickness of 1 mm and annealed at 350 °C, 3 h. After that, tensile mechanical properties were tested. The results of modeling ingot casting were tested in industrial conditions when casting a large ingot with a cross section of 2100×500 mm. A template was cut from the ingot with the dimensions of a billet for rolling, as that obtained from an experimental ingot cast at the SCCU. The billet was subjected to hot and cold rolling according to the conditions used for rolling the experimental ingot. At the same time the modes of heat treatment of sheet semi-finished products were also repeated. The mechanical properties of sheets of alloy 1580 rolled from experimental and industrial ingots practically did not differ. This proves the reliability of casting modes for ingots obtained at the SCCU and tested for casting industrial ingots. |
