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Swelling and mechanical property changes in neutron-irradiated cold-rolled type 316 stainless steel

Description: Samples of cold-rolled Type 316 stainless steel were irradiated in EBR- II to a fluence of about 8 x 10$sup 26$ n/m$sup 2$ (E greater than 0.1 MeV) at 500 and 600$sup 0$C. Three sample configurations were used--small sheet tensile samples, small right-circular cylinders for immersion density, and thin foils for transmission-electron microscopy (TEM). TEM revealed voids in the foils irradiated at both temperatures. Immersion density results, however, indicated swelling only in the sample irradiated at 600$sup 0$C. Considerable recovery and precipitation were observed in foils irradiated at both temperatures. Results of tensile tests on irradiated samples showed a decrease in yield strength and an increase in ductility compared to unirradiated controls. (auth)
Date: January 1, 1975
Creator: Garr, K.R. & Pard, A.G.
Partner: UNT Libraries Government Documents Department

Study of ferrite formation in neutron irradiated austenitic stainless steels. Progress report, June 1, 1973--February 28, 1974

Description: A vibrating reed magnetometer was constructed for measurements on small irradiated samples. It can be operated at 4 to 500 deg K and can detect a magnetic moment of 4 x 10/sup -5/ erg/O/sub e/, with a signal-to-noise ratio of 20. A simple calibration procedure was devised. The magnetometer was used to measure magnetization curves of an irradiated type 316 austenitic stainless steel specimen at two different temperatures. Results confirm that the specimen contains numerous small magnetic particles which are presumed to be ferrite. Transmission electron microscopy of the irradiated specimen was not conclusive for the presence or absence of ferrite. (5 figures) (DLC)
Date: January 1, 1974
Creator: Stanley, J.T. & Hendrickson, L.E.
Partner: UNT Libraries Government Documents Department

Study of ferrite formation in neutron irradiated austenitic stainless steels. Progress report, March 1, 1975--February 29, 1976

Description: Magnetization measurements were carried out on a number of neutron- irradiated austenitic stainless steel specimens. Variation of magnetization with field indicates that the magnetic phase particles are very small so that the particles show superparamagnetic behavior. The temperature dependence of the magnetization indicates that more than one ferromagnetic phase may be present in some of the specimens. Postirradiation annealing at 500$sup 0$C increased the quantity of magnetic phase in specimens that had been irradiated at 425$sup 0$C and annealing in a magnetic field of 33 kOe has the effect of increasing the total quantity of magnetic phase but reducing the average size of the magnetic particles. (auth)
Date: January 1, 1976
Creator: Stanley, J.T. & Hendrickson, L.E.
Partner: UNT Libraries Government Documents Department

Segregation and second phase formation at free surfaces during irradiation

Description: From surface effects in controlled thermonuclear fusion devices and reactors meeting; Argonne, Illinois, USA (10 Jan 1974). Transmission electron microscopy examinations of a number of fcc and bcc metals and alloys irradiated either by heavy-ions or high energy electrons have shown that dynamic interactions of displacement damage with impurities and alloying elements lead to segregation and/or to the formation of second phases at internal surfaces such as voids. The phenomenon has been observed in an experimental 18 Cr-8 Ni-1 Si stainless steel, in commercial 316L stainless steel, in vanadium, and in nickel. Results of analysis of the segregation-induced strain field around the voids indicate that irradiation produces an enrichment of elements with negative size factors and/or depletion of elements with positive size factors. Results of Auger spectroscopic analysis indicates a similar segregation phenomenon occurs at the external irradiated surface in 18 Cr--8Ni-1 Si stainless steel. A comparison of the Auger spectra from surfaces of unirradiated and irradiated samples show that irradiation produces an increase in the nickel and silicon concentration but a decrease in the chromium concentration. Nickel and silicon have negative size factors while for chromium, it is positive. These results suggest that undersized substitutionai elements may tend to preferentially interchange positions with oversized solutes in interstitial sites, and that transport by interstitials may dominate segretation to defect sinks. (auth)
Date: January 1, 1974
Creator: Okamoto, P.R.; Wiedersich, H. & Das, S.K.
Partner: UNT Libraries Government Documents Department

Radiation damage considerations

Description: The designs of nuclear fission and fusion power plants do not, in general, appear to make unusual demands on materials in terms of mechanical- property requirements. Radiation environments produce unique effects on the composition, microstructure, and defect population of these alloys, resulting in time-dependent and time-independent changes in mechanical properties. To illustrate these problems, the materials needs of the core of a Liquid-Metal Fast- Breeder Reactor (LMFBR) and of the first wall of a fusion reactor are discussed. In the case of the LMFBR core, the phenomenon of void swelling causes serious design problems, and a search is being made for a low-swelling alloy that has adequate mechanical properties. The fusion reactor poses different problems because the neutron energy is high (14 MeV) and is accompanied by a high flux of charged particles. The long-term choices for a wall material have been narrowed to vanadium and niobium alloys. In the search for low-swelling alloys, it has become clear that minor elements play an important role in determining the nature of the radiation effects. The segregation of minor elements to void surfaces and the dispersion and reformation of second-phase precipitates are two important radiation-induced phenomena that require additional study in view of their influence on void swelling and high-temperature properties. (auth)
Date: August 1, 1975
Creator: Frost, B.R.T.
Partner: UNT Libraries Government Documents Department