A Comparative Study: the Combined Effect of the Cold Working and Age Hardening Processes on Pitting Behaviour of Al/Sic Metal Matrix Composites Under Saline Environment

Abstract

The combined effect of cold working and age hardening treatment (T8) on the corrosion behaviour of Al-Si-Mg based metal matrix composite reinforced with silicon carbide particles has been investigated in 3.5wt% NaCl solution by potentiodynamic polarization technique. Composites containing 10 and 20 vol% silicon carbide particles were produced by compocasting technique and cold-worked at ratios of 4, 6, 10, 25 and 50% prior to ageing heat treatment conducted at 175 degrees C Corroded surfaces of the composites were observed by using scanning electron microscopy. A significant change in the corrosion behaviour of composites was observed when cold work ratio was increased from 4 to 50%. In addition, it has been found that the influence of cold working on corrosion behaviour is relatively higher compared to the effect of reinforcement content and age-hardening treatment.