Effect of Rare Earth Additions on Grain Refinement of Plain Carbon Steels

Abstract

This paper describes a set of experiments with misch metal and rare earth silicide additions in 1010 and 1030 steel to determine whether grain refinement occurs. Target rare earth (RE) contents of 0.1 and 0.2% were employed. After melting, the desired RE addition was added during tapping and then poured into green sand molds. The resulting test plates were then sectioned for tensile and metallographic testing. Yield strength increased for several of the 1010 and 1030 samples. The increase in yield strength correlated with a reduction in grain size. A dramatic increase in percent elongation was also observed in the 1010 sample with the smallest grain size. Electron microscopy found complex RE oxides. These oxides appear to act as heterogeneous nuclei. When they were coated with another slag, the grain size and mechanical properties were similar to the baseline material in both the 1010 and 1030.