Effect of Oscillating Field on Microstructure of Twin-roll Cast 7075 Aluminum Alloy

The morphology and the hardness of 7075 Al alloy during oscillating twin-roll casting (TRC) process at 670 °C were investigated. It was observed that compared with that by traditional process, the dendritic grains of the strips by oscillation field TRC process were severely broken, refined and equiaxed. Segregation bands at the surface and the center of 7075 strips were dramatically reduced in electromagnetic oscillatory field conditions, even completely disappeared in alternating oscillatory condition. The transverse and the rolling direction HV hardness of 7075 strips manufactured by traditional process were 1104 and 1356 MPa, respectively. Upon applying the electromagnetic field, the maximum hardness of 1615 MPa was obtained in alternating oscillating TRC process. Besides, the properties of strips will be further improved with increasing of magnetic field. No matter in what conditions, the refinement of electromagnetic field to strips will increase at elevated temperature.