Study the Effects of Squeeze Casting Parameters on the Corrosion Behavior of Al-Si-4Cu Alloy

Abstract

This study investigated the effects of squeeze parameters on the properties of squeeze castings and the optimum parameters for producing squeeze castings from Al-Si alloy. It also compared the properties of the squeeze castings with those of gravity castings. Squeeze castings were made from Al-Si-4Cu alloy using pressures of 10,15,20,25 and 30 MPa with the alloy poured at 750, 800 and 850oC into a die preheated to 300oC. Squeeze time was 30s. The corrosion experiments were performed over a range of elevated pressure, pouring temperature and were carried out in sea water (3.5% NaCl solution). We have focused to determination of the rate of corrosion and other corrosion characteristics. Both as-gravity cast and squeeze specimens were tested, for comparison. Corrosion behavior of the materials was assessed by the corrosion potential by potentiostate (polarization) curves. It was found that for a specific pouring temperature,microstructure of squeeze castings became finer;mechanical properties were increased with increase in pressure to their maximum values. Compared with gravity casting process, squeeze casting enhanced the mechanical properties; it increased the hardness from Hv 18.083 Kg for gravity castings to a maximum of Hv 35.413 for squeeze castings which constitutes about 50.063% increase over those of gravity castings. Although squeeze casting parameter has decreased the corrosion current density (of about 2 μAcm2) when compared to the results of the as-cast samples