Effect of gate shape and forging temperature on the mechanical properties in the injection forging process of semi-solid aluminum material

Abstract

Semi-solid materials (SSM) were fabricated under two fabrication conditions by mechanical stirring. Re-heating conditions of SSM with the two fabrication methods (mechanical and electro-magnetic stirring) were studied with two holding times and three re-heating temperatures. SSM forging was conducted with three different die temperatures ( T die=250, 300 and 350°C) and two gate types (straight gate and orifice gate). The mechanical properties of semi-solid forging components can be predicted indirectly, from the microstructure of SSM fabricated at a cooling rate of 0.0094°C s −1 and a stirring speed of 1000 rpm. The initial microstructure of the SSM affects the microstructure of the SSM in the process of re-heating, a smaller initial microstructure providing a more globular microstructure after re-heating. The microstructure of SSM held for 15 min is superior to that of SSM held for 20 min in terms of globulization and size. The effect of die temperature is not serious to fill a die cavity in straight gate die. The mechanical properties of forging components fabricated at the orifice gate die are superior to those of components fabricated at the straight gate, e.g. an ultimate strength of U=320 MPa for the orifice gate compared to an ultimate strength of U=250 MPa for the straight gate.