Investigation of the controlled atmosphere of semisolid metal processing of A356 aluminium alloy

The cooling slope (CS) method is one of the semi-solid methods in which the molten alloy with a suitable amount of superheat is poured on a cooling slope to achieve a fine and non-dendritic structure. After pouring, the melt, which becomes semisolid at the end of the plate, is subsequently poured into a cylindrical steel mold with different mold temperatures. Also, the process has been done in different cooling slopes and different cooling lengths. This work, at first discusses the effect of these parameters on the final microstructure of A356 aluminum alloy and then the effect of the controlled atmosphere is discussed. Also, in this research, the advantages of using the controlled atmosphere system are discussed by tests such as XRD, SEM and ultrasonic test. Results indicate that the pouring temperature, mold temperature, cooling slope and cooling length have significant effects on the size and morphology of α-Al phase. Also, the controlled atmosphere could optimize the process as well and increase the mechanical properties of alloy.