Several copper- and molybdenum-alloyed gray cost irons were cost as one-inch Y-blocks and step bars in green sand. Tensile bars were cut from the base of the Y-blocks. Metallographic specimens were cut from the step bars. Quantitativemetallographic analysis was used to evaluate the matrix microstructures in each of the alloys for both Y-blocks and the four sections of the step bars. Brinell hardness testing was done on the shoulders of the tensile bars and in each of the step barsections.Acicular ausferritic structures were observed in alloys containing greater than 0.5wt% Mo. The addition of Cu to the Mo-alloyed irons promoted increasing amounts of the ausferrite product. Increasing amounts of the ausferrite product resulted inincreasing tensile strengths. The magnitude of the tensile results is consistent with isothermally austempered gray cast irons.
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