STUDY OF STEEL TESTS OF STATIC CORROSION EXPERIMENTS IN LIQUID METAL PB-BI
We try to evaluate the possibility of maintaining the corrosion-resistance of a structural material under the operational temperature and flow velocity of the optimized HYPER (HYbrid Power Extraction Reactor)[1] cooling system. It was attempted to consider the control of the oxygen concentration in the range of 350~650°C. Currently, we are performing static corrosion tests with the oxygen contents of a reduced and 10~ 10 wt% atmospheres at the temperature of 600°C. The concentration was controlled by adjusting the H2 and H2O vapor ratio. In this paper, we will show the result of the experiment performed under the reduced atmosphere with an exposure time up to 1500 hours. The corrosion of 316L is irregularly severe under the reduced atmosphere due to the solubility of the nickel at Pb and Pb-Bi. Also small amount of iron and chromium was dissolved near the surface. On the other hand, the T91 and HT9 maintained the corrosion-resistance under the same condition.
Martensitic/ferritic steels as container materials for liquid mercury target of ESS
In the previous report, the suitability of steels as the ESS liquid mercury target container material was discussed on the basis of the existing database on conventional austenitic and martensitic/ferritic steels, especially on their representatives, solution annealed 316 stainless steel (SA 316) and Sandvik HT-9 martensitic steel (HT-9). Compared to solution annealed austenitic stainless steels, martensitic/ferritic steels have superior properties in terms of strength, thermal conductivity, thermal expansion, mercury corrosion resistance, void swelling and irradiation creep resistance. The main limitation for conventional martensitic/ferritic steels (CMFS) is embrittlement after low temperature ({le}380{degrees}C) irradiation. The ductile-brittle transition temperature (DBTT) can increase as much as 250 to 300{degrees}C and the upper-shelf energy (USE), at the same time, reduce more than 50%. This makes the application temperature range of CMFS is likely between 300{degrees}C to 500{degrees}C. For the present target design concept, the temperature at the container will be likely controlled in a temperature range between 180{degrees}C to 330{degrees}C. Hence, CMFS seem to be difficult to apply. However, solution annealed austenitic stainless steels are also difficult to apply as the maximum stress level at the container will be higher than the design stress. The solution to the problem is very likely to use advanced more » low-activation martensitic/ferritic steels (LAMS) developed by the fusion materials community though the present database on the materials is still very limited. « less
Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions
Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.Copyright © 2004 by ASME