Uranium Addition to Low-Alloy High-Tension Steels
Influence of uranium addition on iron and steel-III
1964 Volume 50 Issue 10 Pages 1440-1449
Details
1964 Volume 50 Issue 10 Pages 1440-1449
In the previous papers, the authors suggested about the behaviour of Fe2U and UC formed in carbon steels that Fe2U was decomposed by the solution treatment over 950°C and UC was very stable even by the solution treatment at 1200°C.
In this paper, the authors reported the results of investigations into the effect of uranium, addition on three low-alloy high-tension steels, Si-Mn series, Mo-B series and Cr-Ni-Cu series, and into uranium application instead of molybdenum in order to obtain a bainitic structure.
For Si-Mn series, the effect of uranium is almost the same as in the previous papers. Impact resistance at low temperature is reduced by addition of uranium and the transition temperature increases remarkably.The merit of uranium addition to this series is the formation of stable carbide and improvement of corrosion resistance against dilute hydrochloric. acid.
For Mo-B series, no effect is recognized in normalizing at 920°C, but at 1150°C, the bainitic structures of the specimen containing uranium become very fine and have an increased in hardness.The same effect is observed in the hardenability test. This finer microstructure has higher tempering resistance than the standard one, and secondary hardening occursat the tempering temperature of 550-600°C. As compared with the effects of other elements, the effect of uranium is as little as niobium but less than V, W and Ti. It indicates that the solubility of uranium to austenite is improved by the coexistence of molybdenum and uranium precipitates in the carbide reaction of tempering. But insoluble carbide is retained at the previous austenite grain boundary in the steel containing excessive uranium. The bainitic structure is gained in 0.48% uranium steel normalized at 1150°C, but this structure has not so high tempering resistance as that of molybdenum-bearing steels.
For Cr-Ni-Cu series, the effect of uranium is similar to that of molybdenum, but of mecha-nical properties the ductility and impact resistance are reduced by the addition of uranium. Slight secondary hardening based on the precipitaion of uranium appears in this series through the high temperature solution treatment. This is different from the Si-Mn series.
