Al,Zr–FeSi preconditioning of grey cast irons

Abstract

Laboratory research has been conducted to investigate the effect of strong deoxidising elements such as Al, Zr or Ti in preconditioning of uninoculated and inoculated grey irons. Experimental heats were performed in an acid lined crucible induction furnace at 3˙7–3˙9% carbon equivalent, 5˙5–6˙5 Mn/S ratio and, <0˙005%Al and Ti. The content of 0˙027–0˙028%Al, 0˙011–0˙017%Ti or 0˙011–0˙013%Zr was obtained in preconditioned irons. Not only inoculation but also the preconditioning of the base iron has a strong effect on the solidification pattern. Preconditioning led to an improved level measuring the most significant temperatures of cooling curves and resulted in a positive trend of eutectic and of the end of solidification representative parameters, in both uninoculated and inoculated irons. A foundry case study is represented to illustrate the efficiency of Al and Zr bearing FeSi preconditioning of electrically melted, inoculated grey iron: decreasing the eutectic undercooling and recalescence, improved graphite characteristics, avoiding carbides, increased tensile strength, while heat treatment was eliminated, for 5 mm sections castings.