Effect of silicon on microstructure and wear resistance of aluminum bearing gray cast iron

Gray cast iron is among the most common and important engineering material that plays a significant role and has many applications in various industries, including the automotive and machinery manufacturing. It still attracts researchers’ interest to improve its properties and maintain its position among the engineering materials. In this research, the microstructure of plain cast iron as well as those containing 4 wt% aluminum with different amounts of silicon, 1 to 4 wt%, was studied. Pin-on-disc method was used to evaluate the wear resistance of the cast irons. The results showed that the addition of aluminum to gray cast iron brings about the formation of ferrite phase, which accompanies a decrease in hardness value. In addition, the increase in silicon content in aluminum bearing cast iron up to 2wt% intensifies the formation of ferrite phase, while the further increase to 3 wt% results in emerging a Fe-Al-Si intermetallic compound. In gray cast iron with constant 4 wt% aluminum, increasing silicon content to 3 wt% and 4 wt% leads to improve the hardness value due to the increased percentage of intermetallic phase. Confirming microstructure evolution as well as hardness values, the results of wear experiment approved lower wear rate in cast irons containing intermetallic phase. In contrast, the lowest wear resistance was observed in aluminum bearing cast iron containing 2 wt% silicon.