THE COOLING TRANSFORMATIONS IN CERTAIN URANIUM-BEARING STEELS.
NAVAL RESEARCH LAB WASHINGTON D C
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The continuous cooling transformation of three laboratory heats, containing 0, 0.06, and 1.1 percent natural uranium U, and of a uranium-free commercial heat, following austenitizing at 1650 and 1750 F, have been investigated. The melts were prepared to the nominal composition for ASTM A212-B steel. Hardness measurements, as well as metallographic examinations, of the transformed structures were included in this study. The two uranium-free steels yielded very similar cooling-transformation diagrams and exhibited essentially equivalent hardenability however, the hardenability of the uranium-free commercial heat was limited by ferrite and upper bainite formation, while that of the laboratory heat was restricted by pearlite formation. Uranium additions of 0.06 and 1.1 percent were not found to have any significant effect upon hardenability although, unlike the uranium-free laboratory heat, the hardenability of these steels was limited by upper bainite formation. Suppression of the proeutectoid ferrite reaction at intermediate cooling rates was observed to increase with uranium content. Metallographic examinations of the 1.1-percent U steel revealed a stringer dispersion of a micro-constituent, possibly Fe2U, in all structures produced over the range of cooling conditions employed. The volume of this phase was small, however, and thus is not believed to have a serious effect on austenite decomposition when quenching. Author