Effects of testing and storage environments on mechanical properties of Ni-plated and bare U-3/4 wt% Ti

It was found that storage environments with an adequate supply of oxygen can effectively minimize moisture corrosion of bare U-3/4 Ti. In particular, 0.75 cm/sup 3/ of dry air is calculated to protect 1 cm/sup 2/ of U-3/4 Ti for 20 years storage at room temperature. Consideration of the geometric details of U-3/4 Ti alloy specimens and the free volumes of air (and hence O/sub 2/) available can satisfactorily explain discrepancies in corrosion behavior between recent tests and previously reported data. The storage environment at 70/sup 0/C produces a minor strength increase in bare samples with increasing time. Decreases in ductility are observed for testing conditions of low temperature, low strain rate, and/or high humidity. Surface cracks occur under the same conditions conducive to corrosion, i.e., moderate temperatures, low strain rates, and high humidity. Significant increases in strength result under low-temperature and high-strain-rate conditions of tensile testing. Residual chloride contamination may be responsible for the occasional and otherwise unexplained large scatter in ductility for nominally similar specimens and test conditions. Nickel plating is observed to cause a statistically significant decrease in tensile strength, but no effect on the yield strength or ductility was observed and the presence of high explosivemore » during the aging of tensile bars was observed to have no effect on mechanical properties.« less