Effects of Ultrasonic and Electromagnetic Field on Structure and Properties of Roll-Casting 1050 Aluminium Alloy Strips

A compound nozzle which was used to be asymmetric and sunken was developed for roll-casting aluminum alloy billet. When the new nozzle was adopted, the best casting speed which was increased by 30% than that of the symmetric nozzle ranged from 1.2m/min to 1.4m/min. The effects of compound energy-field (ultrasonic and electromagnetic field) on structure and properties of roll-casting 1050 aluminum alloy strip were investigated as well. The macro-metallographic observation showed that the compound energy-field can effectively refine the grain (to Grade 1), weaken the central layer segregation. The results of the metallographic observation of combining energy-field and general roll-casting aluminum strip showed that the grains of general roll-casting aluminum strips were big, most of which were charactered as columnar crystals. The cellular dendrite was coarse and the grain structure was heterogeneous, and the average grain diameter was 90μm~100μm. However, the microstructure of roll-casting aluminum sheet was fine equiaxed grains with combining energy-field treatment and the grain structure became more homogenize, while the grain was refined and the average grain diameter was 35μm~40μm. Besides, the results of the mechanical properties indicated that the tensile strength, yield strength and elongation of combining energy-field roll-casting aluminum strip were improved by 23.80%, 23.77% and 38.70% respectively than that of general roll-casting aluminum strip.