Effect of titanium on the as-cast microstructure of a 16%chromium white iron

This research work studies the effect of systematic titanium additions (up to 2 wt.%) to a 16%Cr, 2.5%C white cast iron. The study was undertaken in six laboratory made alloys with different titanium amounts. Alloys were melted in an open induction furnace by using high purity raw materials. Such additions caused small hard titanium carbide particles to precipitate within the proeutectic austenite therefore promoting a strengthening of matrix; such particles also contributed to increase bulk hardness of the overall alloy. A structure refinement, as measured by the secondary dendrite arm spacing, was also observed as the titanium amount was increased. Titanium carbide precipitation caused a small decrease in the eutectic carbide volume fraction. The fracture toughness remained constant since the strengthening of matrix was compensated with a decrease in the volume of eutectic carbides. According to this study, titanium can be used as an alloying element to increase the hardness and perhaps wear resistance without affecting fracture toughness in high-chromium cast alloys. The results are discussed in terms of the precipitation nature of such small hard titanium particles.