The effect of forging pressure on liquid segregation during direct rheoforging process of wrought aluminium alloys fabricated by electromagnetic stirring

摘要

This study demonstrated rheoforging of wrought aluminium alloys fabricated by means of electromagnetic stirring (EMS) and characterization of the rheoforged products. When EMS was applied under a stirring current of 60 A, infusion of surface oxides into the bulk material and porosities within the bulk material were both prevented and dendrites were crushed. Material rheoforged at a densification pressure of 150 MPa exhibited good mechanical strength and surface quality. The temperature of the rheological material during forging influences the formability of the material. When the solid fraction is below 70 per cent, the rheological material completely fills the die cavity and the pressure applied by the punch is transferred to the material at the bottom of the die cavity. Investigating the microstructural features and mechanical properties of the material, it is shown that the rheoforged material following EMS yields a fine and globular microstructure.