[en] The role of grain boundary precipitate structure on the stress corrosion susceptibility of 18Ni(250) maraging steel was examined. Varying solution treatment procedures were used to achieve either a precipitate-free grain boundary or one containing a high density of Ti(C,N) particles. The introduction of these treatments, although drastically affecting the monotonic fracture toughness, did not significantly alter the stress corrosion threshold in 100 percent relative humidity. These results are shown to be consistent with the previous suggestion that, under open circuit conditions, hydrogen-assisted cracking controls the environmental crack growth behavior of 18Ni maraging steels. (U.S.)

[en] The dimensional stability of Ti-6Al-6V-2Sn has been examined. It is shown that in the duplex annealed condition Ti-6Al-6V-2Sn is dimensionally stable at temperatures up to 448⁰K for 512 hrs. Solution treated Ti-6Al-6V-2Sn undergoes large dimensional changes during both initial aging between 673 and 973⁰K and subsequent exposure to low temperatures (< or = to 448⁰K). These results indicate that if close dimensional tolerances must be maintained, duplex annealed Ti-6Al-6V-2Sn should be selected. Selection of treated and aged Ti-6Al-6V-2Sn should only be considered if accompanied by full scale environmental testing

[en] The alloy composition is 10.2 Mo, 5.8 Zr, 4.7 Sn, 0.03 Fe, 0.014 N, 0.02 C, 0.13 O, bal. Ti. The fracture toughness increases with the solution treatment, but this effect lessens with decreasing test temperature. Solution treating above the beta transus resulted in a fracture toughness insensitive to test temperatures above 273⁰K; below, the toughness decreased almost linearly to 77⁰K. Sub-transus treated alloy exhibited a linear toughness decrease over the entire temperature range. SEM observations are reported

[en] The literature has been reviewed to determine the possible influences of strain rate and temperature on the yield and fracture toughness behavior of selected steels suggested for use in an LMFBR Spent Fuel Shipping Cask. Based on this information, recommendations have been made for further work which is intended to alleviate potential problems prior to their having a major impact on the shipping cask program

[en] The influence of notch included angle and root radius on the apparent dynamic fracture toughness of an unaged metastable beta titanium alloy, Ti--3Al--8V--6Cr--4Zr--4Mo, has been examined. The apparent fracture toughness, K/sub Id/(rho), increases with both notch radius, rho and included angle, ω. These results have been compared with the theoretical predictions of Tetelman, et al. and Smith. The comparisons show that neither theory accurately describes the effect of varying notch constraint on the apparent dynamic fracture toughness. Although preliminary considerations indicate that qualitative descriptions of notch acuity effects may be given by recent finite element analysis of the stress and strain distributions below a notch root, there is presently no quantitative basis for determining the true dynamic fracture toughness of materials from the results of blunt notch experiments. (auth)

[en] The physical and mechanical properties of an overaged 17-4 PH stainless steel casting have been examined. The tensile and compressive properties of cast 17-4 PH are only influenced to a slight degree by changing test temperature and strain rate. However, both the Charpy impact energy and dynamic fracture toughness exhibit a tough-to-brittle transition with decreasing temperature - this transition being related to a change in fracture mode from ductile, dimple to cleavage-like. Finally, although the overaged 17-4 PH casting had a relatively low room temperature Charpy impact energy when compared to wrought 17-4 PH, its fracture toughness was at least comparable to that of wrought 17-4 PH. This observation suggests that prior correlations between Charpy impact energies and fracture toughness, as derived from wrought materials, must be approached with caution when applied to cast alloys

[en] A description of a facility devoted to evaluating the environmental compatibility and mechanical response of materials suitable for a breeder reactor spent-fuel shipping cask is given. The facility presently consists of a closed-loop servo-controlled hydraulic, horizontal test system coupled to an environmental chamber, generalized mechanical test equipment and high-rate mechanical behavior apparatus. Future plans include the procurement of real-time computer control equipment which will be used to assess the effects of complex load-time histories on spent-fuel shipping cask materials

No abstract available

[en] A potmortem examination of a large fire-exposed rail-transported spent fuel shipping container has revealed the presence of two macrofissures in the outer cask shell. The first, a part-thru crack located within the seam weld fusion zone of the outer cask shell, was typical of hot cracks that may be found in stainless steel weldments. The second, located within the stainless steel base metal, apparently originated at microcracks formed during the welding of a copper-stainless steel dissimilar metal joint. The latter microcrack then propagated during the fire-test, ultimately penetrating the outer shall of the cask. 18 figures, 2 tables

[en] Slow strain rate testing has shown that the macroscopic tensile properties of mill-annealed TiCode 12 are not affected by exposure to either a synthetic seawater or high chloride brine environment. However, microscopic examination indicates that the fracture mode may be sensitive to environment. This sensitivity appears to be related to hydrogen ingress during prolonged exposure