Effect of aluminum content on the microstructural and mechanical properties of a low alloyed steel

Abstract

The alloying elements that are added to steel during the steelmaking process have a crucial impact on its microstructural properties even when their presence is limited to only a few traces. In this project, the effects of aluminum traces were investigated. The studied samples have been elaborated in the AQS comlex in the Steel Melt Shop and Rolling Machines units. The CDRI pellets were put into the electric arc furnace to be melted, additions were added in the ladle refining furnace and the billet was formed in the continuous casting machines. Three heats of steel with different aluminum contents were submitted for testing. The study was carried out on samples taken from the steel billet and the wire rod. The steel billet samples were submitted to chemical characterization by XRF, and then received annealing treatments at different heating temperatures and holding times. Optical microscopy for microstructural analysis and hardness test were applied on each of them, while the wire rod samples received th OM, hardness, and tensile testing, Resultas showed that aluminum forms non-metallic inclusions in the form of alumina that precipitate on grain boundaries, which will cause a decrease in the grain size; however, the microstructure was completely cleaned at 1100°C, 6h annealing. Mechanical testing showed that this variation of the grain size could affect directly the mechanical properties of the samples.