Download or read book Microstructural Evolution of Austenitic Stainless Steels Irradiated to 17 Dpa in Spectrally Tailored Experiment of the ORR and HFIR at 400 degrees C written by and published by . This book was released on 1997 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstructural evolution of austenitic JPCA aged and solution annealed JPCA, 316R, C, K, and HP steels irradiated at 400°C in spectrally tailored experiments of the ORR and HFIR has been investigated. The helium generation rates were about 12-16 appm He/dpa on the average up to 17.3 dpa. The number densities and average diameters of dislocation loops in the steels have ranges of 3.3 x 1021 m−3 and 15.2-26.3 nm, respectively, except for HP steel for which they are 1.1 x 1023 m−3 and 8.0 nm. Precipitates are formed in all steels except for HP steel, and the number densities and average diameters have ranges of 5.2 x 102° - 7.7 x 1021 m−3 and 3.4- 19.3 nm, respectively. In the 216R, C, and K steels, the precipitates are also formed at grain boundaries, and the mean sizes of these are about 110, 50, and 50 nm, respectively. The number densities of cavities are about 1 x 1022 m−3 in all the steels. The swelling is low in the steels which form the precipitates.

Download or read book Effect of Ti and C on the Microstructural Evolution of Rapidly Solidified Austenitic Stainless Steels Under Dual Ion Irradiation written by Chiang-Hsiung Tong and published by . This book was released on 1983 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Official Communiqu of the 4821st closed Meeting of the Security Council Held in Private at Headquarters New York on Tuesday 9 September 2003 written by and published by . This book was released on 2003 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Observation and Interpretation of Microstructural Evolution and Swelling in Austenitic Steels Under Irradiation written by N. Sekimura and published by . This book was released on 1994 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation behavior of model austenitic steels is investigated to establish mechanistic modeling of swelling and other property changes under irradiation. Neutron irradiation experiments were performed using Material Open Test Assembly (MOTA) at 693, 793 and 873 K to 35 to 40 dpa in the Fast Flux Test Facility (FFTF) cycles 10 and 11. Cavity formation and dislocation development were quantitatively estimated to evaluate the effect of temperature history on the microstructural evolution under irradiation in fission reactors. Fine dislocation loops observed in the matrix of the alloys irradiated in cycle 10 were considered to come from the low-temperature irradiation during the reactor shut-down at the end of the cycle. Very few small loops were detected in identical specimens irradiated in FFTF cycle 11 where the reactor power and temperature were simultaneously decreased a short time during the shut-down.

Download or read book Effect of Heavy Ion Irradiation on Microstructural Evolution in CF8 Cast Austenitic Stainless Steel written by and published by . This book was released on 2015 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstructural evolution in ferrite and austenitic in cast austenitic stainless steel (CASS) CF8, as received or thermally aged at 400 °C for 10,000 h, was followed under TEM with in situ irradiation of 1 MeV Kr ions at 300 and 350 °C to a fluence of 1.9 × 1015 ions/cm2 (~3 dpa) at the IVEM-Tandem Facility. For the unaged CF8, the irradiation-induced dislocation loops appeared at a much lower dose in the austenite than in the ferrite. At the end dose, the austenite formed a well-developed dislocation network microstructure, while the ferrite exhibited an extended dislocation structure as line segments. Compared to the unaged CF8, the aged specimen appeared to have lower rate of damage accumulation. The rate of microstructural evolution under irradiation in the ferrite was significantly lower in the aged specimen than in the unaged. Finally, we attributed this difference to the different initial microstructures in the unaged and aged specimens, which implies that thermal aging and irradiation are not independent but interconnected damage processes.

Download or read book Irradiation Creep in Austenitic Stainless Steels at 60 to 400 C with a Fusion Reactor Helium to Dpa Ratio written by M. P. Tanaka and published by . This book was released on 1990 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation creep was investigated in the alloys--prime candidate alloy (PCA), Japanese Fusion Energy Program (JPCA), and American Iron and Steel Institute (AISI) 316 (UNS S31600) stainless steel. Tubes pressurized to stress levels of 50 to 400 MPa were irradiated in the Oak Ridge Research Reactor (ORR) with the neutron spectrum tailored to achieve the fusion reactor helium:dpa value of 12 appm/dpa in AISI 316 stainless steel. Irradiation temperatures of 60, 330, and 400°C were investigated, and the irradiation produced 8 dpa and a maximum of about 100 appm helium. Irradiation creep rates of 2.2 to 14x10-4MPa-1dpa-1 were observed at 60°C. At 330 and 400°C irradiation creep rates of 1.3 to 3.5x10-4 were observed, similar to those found previously in similar experiments in the ORR. The low temperature irradiation creep was interpreted in terms of a new model for irradiation creep based on transient climb-enabled glide. The results are important in the design of experimental fusion reactors where temperatures below 100°C are being considered for the operation of high flux components.

Download or read book Microstructural Evolution of HFIR irradiated Low Activation F82H and F82H sup 10 B Steels written by and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microstructures of reduced-activation F82H (8Cr-2W-0.2V-0.04Ta) and the F82H steels doped with 1°B, irradiated at 250 and 300 C to 3 and 57 dpa in the High Flux Isotope Reactor (HFIR), were examined by TEM. In the F82H irradiated at 250 C to 3 dpa, dislocation loops, small unidentified defect clusters with a high number density, and a few MC precipitates were observed in the matrix. The defect microstructure after 300 C irradiation to 57 dpa is dominated by the loops, and the number density of loops was lower than that of the F82H-1°B steel. Cavities were observed in the F82H-1°B steels, but the swelling value is insignificant. Small particles of M6C formed on the M23C6 carbides that were present in both steels before the irradiation at 300 C to 57 dpa. A low number density of MC precipitate particles formed in the matrix during irradiation at 300 C to 57 dpa.

Download or read book Void Swelling and Microstructure of Austenitic Stainless Steels Irradiated in the BOR 60 Reactor written by and published by . This book was released on 2012 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: As nuclear power plants age and neutron fluence increases, detrimental effects resulting from radiation damage have become an increasingly important issue for the operational safety and structural integrity of core internal components. In this study, irradiated specimens of reactor core internal components were characterized by transmission electron microscopy. The specimens had been irradiated to 5.5-45 dpa in the BOR-60 reactor at a dose rate close to 10-6 dpa/s and temperature of about 320°C. No voids were observed in the austenitic stainless steels and nickel alloys at all doses. Despite the possibility that fine voids below the TEM resolution limit may be present, it was clear that void swelling was insignificant in all examined alloys up to 45 dpa. Irradiated microstructures of the studied alloys were dominated by a high density of Frank loops. The mean size and density of the Frank loops varied from one material to another, but saturated with increasing dose above ~10 dpa. While no irradiation-induced precipitations were present below 24.5 dpa, fine precipitates were evident in several alloys at 45 dpa.

Download or read book Swelling Microstructural Development and Helium Effects in Type 316 Stainless Steel Irradiated in HFIR and EBR II written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work examines the swelling and microstructural development of a single heat of 20%-cold-worked type 316 stainless steel irradiated to produce displacement damage and a high, continuous helium generation rate, in the High Flux Isotope Reactor (HFIR). Similar irradiation of the same heat of steel in the Experimental Breeder Reactor (EBR)-II is used as a base line for comparing displacement damage accompanying a very low continuous helium generation rate. At temperatures above and below the void swelling regime (approx. 350 to 625°C) swelling is greater in HFIR than in EBR-II. In the temprature range of 350 to 625°C, cavity formation, precipitation and dislocation recovery are both enhanced and accelerated in HFIR, often causing swelling at lower dose than in EBR-II. In HFIR, however, cavities appear to be bubbles rather than voids. They are about 10 times smaller and 20 to 50 times more numerous than voids in EBR-II. Thus, the swelling becomes greater in EBR-II than in HFIR for 20%-CW 316 in the void swelling temperature ranges as fluence increases. Such differences in swelling and microstructural behavior must be understood in order to anticipate the behavior of materials during fusion irradiation.

Download or read book Some Implications of Radiation induced Property Changes in Austenitic Stainless Steels on ITER International Thermonuclear Experimental Reactor First wall Design and Performance written by and published by . This book was released on 1990 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: New data on radiation-induced hardening, low-temperature creep and potential susceptibility (sensitization) to aqueous corrosion have been obtained on various heats of austenitic stainless steel (including type 316) irradiated at 60--400°C to 7--13 dpa. The data were obtained from spectral-tailoring reactor experiments, whose radiation-damage parameters are similar to those in the proposed International Thermonuclear Experimental Reactor (ITER) first-wall (FW) and blanket design. Austenitic stainless steels were found to increase significantly in strength at 60--330°C, to have higher irradiation-creep rates at 60°C than at 200--400°C, and to show radiation-induced changes in electrochemical properties at 200--400°C. These data on several radiation-induced property changes suggest that type 316 steel may be an adequate material for the FW of ITER. However, there is definitely a need for new data on fracture-toughness and on fatigue behavior below 400°C, as well as more data on irradiation-creep and effects of irradiation on corrosion properties to better define temperature and dose dependencies for more detailed design analyses. Cold-working should remain an optional as-fabricated condition for the FW of ITER. Many properties of SA and CW 316 become similar after irradiation at 60--400°C. The higher initial yield-strength of CW 316 will allow higher design stress and elastic strain limits. 31 refs., 10 figs.

Download or read book Comparison of the Effects of Long term Thermal Aging and HFIR Irradiation on the Microstructural Evolution of 9Cr 1MoVNb Steel written by and published by . This book was released on 1990 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both thermal aging at 482--704°C for up to 25,000h and HFIR irradiation at 300--600°C for up to 39 dpa produce substantial changes in the as-tempered microstructure of 9Cr-1MoVNb martensitic/ferritic steel. However, the changes in the dislocation/subgrain boundary and the precipitate structures caused by thermal aging or neutron irradiation are quite different in nature. During thermal aging, the as-tempered lath/subgrain boundary and carbide precipitate structures remain stable below 650°C, but coarsen and recover somewhat at 650--704°C. The formation of abundant intergranular Laves phase, intra-lath dislocation networks, and fine dispersions of VC needles are thermal aging effects that are superimposed upon the as-tempered microstructure at 482--593°C. HFIR irradiation produces dense dispersions of very small black-dot'' dislocations loops at 300°C and produces helium bubbles and voids at 400°C At 300--500°C, there is considerable recovery of the as-tempered lath/subgrain boundary structure and microstructural/microcompositional instability of the as-tempered carbide precipitates during irradiation. By contrast, the as-tempered microstructure remains essentially unchanged during irradiation at 600°C. Comparison of thermally aged with irradiation material suggests that the instabilities of the as-tempered lath/subgrain boundary and precipitate structures at lower irradiation temperatures are radiation-induced effects, whereas the absence of both Laves phase and fine VC needles during irradiation is a radiation-retarded thermal effect.

Download or read book Radiation induced Changes in Microstructure written by F. A. Garner and published by ASTM International. This book was released on 1987 with total page 919 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Minor Alloying Elements and Stress on Microstructural Evolution and Void Swelling of Austenitic Steels Under Neutron Irradiation written by R. Hübner and published by . This book was released on 2000 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: A pressurized tube experiment was carried out in the British Prototype Fast Reactor (PFR) at Dounreay, U.K. in order to determine swelling and stress-induced swelling of four heats of the commercial German austenitic steel DIN 1.4970, with different contents of the minor alloying elements Si, Ti and Ti/C ratio. The maximum doses achieved are 106 dpaNRT at 420°C, 81 dpaNRT at 500°C and 61 dpaNRT at 600°C. The hoop stresses of the pressurized tubes were 0, 60 and 120 MPa at all irradiation temperatures. TEM-examinations have been carried out to determine the influence of the minor alloying elements and the stress on the void swelling and the microstructural evolution. All alloys exhibited the highest swelling values at 420°C and no swelling at 600°C. The measurements show the large effect of the minor alloying elements upon swelling and in-pile creep. The maximum swelling suppression is achieved by a high Si-content and an understoichiometric Ti/C ratio (understabilization). The analysis of the microstructural evolution shows that the swelling resistance is correlated to the formation and stability of very fine ?'-precipitates. For the alloy with the highest swelling resistance these precipitates can be found up to 106 dpaNRT at 420°C, whereas they dissolve in the course of irradiation for the alloys with lower swelling resistance.

Download or read book Microstructural Evolution of Martensitic Steels During Fast Neutron Iradiation written by and published by . This book was released on 1989 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation of martensitic/ferritic steels with fast neutrons (E> 0.1 MeV) to displacement damage levels of 30--50 dpa at temperatures of 300--500°C produces significant changes in the as-tempered microstructure. Dislocation loops and networks can be produced, irradiation-induced precipitates can form, the lath/subgrain boundary structure and the thermal precipitates produced during tempering can become unstable, and if helium is present, bubbles and voids can form. These microstructural changes caused by irradiation can have important effects on the properties of this class of steels for both fast breeder reactor (FBR) and magnetic fusion reactor (MFR) applications. The purpose of this paper is to compare reactor-irradiated and long-term thermally aged 9Cr--1MoVNb specimens, in order to distinguish effects due to displacement damage from those caused by elevated-temperature exposure alone. 7 refs., 1 fig.

Download or read book Void precipitate Association During Neutron Irradiation of Austenitic Stainless Steel written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microstructural data has recently become available on a single heat of 316 stainless steel irradiated in EBR-II and HFIR, over a wide range of irradiation temperature (55 to 750°C), dose (7 to 75 dpa), and helium generation rate (0.5 to 55 at. ppM He/dpa). Extensive information on precipitate compositions and characteristics are included. The data reveal several important relationships between the development of voids and precipitation. Precipitate associated voids dominate the swelling of (DO heat) 316 at 500 to 650 C from 8.4 to 36 dpa in EBR-II. Cold work (CW) or helium preinjection delay void formation in EBR-II. Higher helium generation in HFIR also delays void formation at 500 to 640°C in SA 316 and CW DO heat 316. The delay persists in CW 316 at least to 61 dpa in HFIR, but abundant matrix and precipitate-associated voids form in SA after 47 dpa. In another heat of CW 316 (N-lot) irradiated in HFIR matrix and precipitate voids form readily after 22 to 44 dpa at 500 to 600°C.

Download or read book Microstructure Evolution During Irradiation Volume 439 written by Ian M. Robertson and published by . This book was released on 1997-06-25 with total page 770 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book from MRS discusses the evolution of a material's microstructure as a result of its interaction with energetic particles such as ions, neutrons or electrons. The book is inter-disciplinary and emphasizes all classes of materials including metals, intermetallic compounds, ceramics, polymers, superconductors, semiconductors and insulators. A strong focus is placed on experimental techniques for measuring and quantifying damage and microstructure changes, and on computer simulation techniques for predicting and understanding this phenomena. Topics include: ion-implantation damage in semiconductors; radiation damage in metals; radiation damage in ceramics; radiation effects in polymers and beam-induced effects.

Download or read book Fission fusion Correlations for Swelling and Microstructure in Stainless Steels written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The initial irradiated structural materials data base for fusion applications will be developed in fission reactors. Hence, this data may need to be adjusted using physically-based procedures to represent behavior in fusion environments, viz. - fission-fusion correlations. Such correlation should reflect a sound mechanistic understanding, and be verified in facilities which most closely simulate fusion conditions. In this paper we review the effects of only one of a number of potentially significant damage variables, the helium to displacement per atom ratio, on microstructural evolution in austenitic stainless steels. Dual-ion and helium preinjection data are analyzed to provide mechanistic guidance; these results appear to be qualitatively consistent with a more detailed comparison made between fast (EBR-II) and mixed (HFIR) spectrum neutron data for a single heat of 20% cold-worked 316 stainless steel. These two fission environments bound fusion (He/dpa ratios. A model calibrated to the fission reactor data is used to extrapolate to fusion conditions. Both the theory and broad empirical observation suggest that helium to dpa ratios have both a qualitative and quantitative influence on microstructural evolution; and that the very high and low ratios found in HFIR and EBR-II may not result in behavior which brackets intermediate fusion conditions.