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Effects of irradiation temperature on Charpy and tensile properties of high-copper, low upper-shelf, submerged-arc welds

Description: This paper presents analyses of the Charpy impact and tensile test data, including adjustments for irradiation temperature and fluence normalization which make possible comparison of the irradiation sensitivity of the different welds. Analyses revealed dependence of yield and ultimate strength on irradiation temperature {minus}0.8 MPA/{degrees}C, respectively. Similarly, the Charpy impact energy changes due to irradiation temperature were {minus}0.5{degrees}C/{degrees}C for transition shift and {minus}0.05 J/{degrees}C for upper-shelf energy decrease. After adjustment to an irradiation temperature of 288{degrees}C and normalization to a fluence of 8 {times} 10{sup 18} neutrons/cm{sup 2} percentage increases in yield strength due to irradiation ranged from about 21 to 35% while those for ultimate strength ranged from about 13 to 20%. The Charpy transition temperature shifts ranged from 59 to 123{degrees}C while the postirradiation upper-shelf energies ranged from 58 to 79 J.
Date: December 31, 1992
Creator: Nanstad, R. K. & Berggren, R. G.
Partner: UNT Libraries Government Documents Department

The effect of aging at 343{degree}C on the mechanical properties and microstructure of type 308 stainless steel weldments

Description: The effect of long-term aging at intermediate temperatures on the mechanical properties of stainless steel welds has been studied. Three type 308 multipass shielded metal-arc welds with ferrite levels of 4, 8, and 12% were aged up to 20,000 h at 343C. Tensile tests showed little effect of aging on either the yield or ultimate tensile strengths, but the impact toughness was significantly degraded. The extent of the degradation increased with increasing ferrite content and increasing aging time. Examination of the microstructure with transmission electron microscopy and atom probe field-ion microscopy revealed that the ferrite phase had undergone spinodal decomposition as a result of aging. In addition, G-phase particles were observed at dislocations, and finer G-phase particles were homogeneously distributed throughout the ferrite phase. The changes in the mechanical properties and the fractography are discussed in light of the observed changes in the microstructure.
Date: December 31, 1992
Creator: Alexander, D. J.; Alexander, K. B.; Miller, M. K. & Nanstad, R. K.
Partner: UNT Libraries Government Documents Department

Effects of nonstandard heat treatment temperatures on tensile and Charpy impact properties of carbon-steel casting repair welds

Description: This report discusses carbon steel castings which are used for a number of different components in nuclear power plants, including valve bodies and bonnets. Components are often repaired by welding processes, and both welded components and the repair welds are subjected to a variety of postweld heat treatments (PWHT) with temperatures as high as 899{degrees}C (1650{degrees}F), well above the normal 593 to 677{degrees}C (1100 to 1250{degrees}F) temperature range. The temperatures noted are above the A1 transformation temperature for the materials used for these components. A test program was conducted to investigate the potential effects of such ``nonstandard`` PWHTs on mechanical properties of carbon steel casting welds. Four weldments were fabricated, two each with the shielded-metal-arc (SMA) and flux-cored-arc (FCA) processes,with a high-carbon and low-carbon filler metal in each case. All four welds were sectioned and given simulated PWHTs at temperatures from 621 to 899{degrees}C (1150 to 1650{degrees}F) in increments of 56{degrees}C (100{degrees}F) and for times of 5, 10, 20, and 40 h at each temperature. Hardness, tensile, and Charpy V-notch (CVN) impact tests were conducted for the as-welded and heat-treated conditions.
Date: April 1, 1993
Creator: Nanstad, R. K.; Goodwin, G. M. & Swindeman, M. J.
Partner: UNT Libraries Government Documents Department

Crack-arrest tests on two irradiated high-copper welds. Phase 2: Results of duplex-type experiments

Description: The objective of the Heavy-Section Steel Irradiation Program Sixth Irradiation Series is to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest toughness data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288{degrees}C to an average fluence of 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). This is the second report giving the results of the tests on irradiated duplex-type crack-arrest specimens. A previous report gave results of tests on irradiated weld-embrittled-type specimens. Charpy V-notch (CVN) specimens irradiated in the same capsules as the crack-arrest specimens were also tested, and a 41-J transition temperature shift was determined from these specimens. {open_quotes}Mean{close_quote} curves of the same form as the American Society of Mechanical Engineers (ASME) K{sub la} curve were fit to the data with only the {open_quotes}reference temperature{close_quotes} as a parameter. The shift between the mean curves agrees well with the 41-J transition temperature shift obtained from the CVN specimen tests. Moreover, the four data points resulting from tests on the duplex crack-arrest specimens of the present study did not make a significant change to mean curve fits to either the previously obtained data or all the data combined.
Date: March 1, 1994
Creator: Iskander, S. K.; Corwin, W. R. & Nanstad, R. K.
Partner: UNT Libraries Government Documents Department

Irradiation effects on fracture toughness of two high-copper submerged-arc welds, HSSI series 5. Volume 2, Appendices E and F

Description: The Fifth Irradiation Series in the Heavy-Section Steel irradiation (HSSI) Program was aimed at obtaining a statistically significant fracture toughness data base on two weldments with high-copper contents to determine the shift and shape of the K{sub lc} curve as a consequence of irradiation. The program included irradiated Charpy V-notch impact, tensile, and drop-weight specimens in addition to compact fracture toughness specimens. Compact specimens with thicknesses of 25.4, 50.8, and 101.6 mm [1T C(T), 2T C(T), and 4T C(T), respectively] were irradiated. Additionally, unirradiated 6T C(T) and 8T C(T) specimens with the same K{sub lc} measuring capacity as the irradiated specimens were tested. The materials for this irradiation series were two weldments fabricated from special heats of weld wire with copper added to the melt. One lot of Linde 0124 flux was used for all the welds. Copper levels for the two welds are 0.23 and 0.31 wt %, while the nickel contents for both welds are 0.60 wt %. Twelve capsules of specimens were irradiated in the pool-side facility of the Oak Ridge Research Reactor at a nominal temperature of 288{degree}C and an average fluence of about 1.5 {times} 10{sup 19} neutrons/cm{sup 2} (> 1 MeV). This volume, Appendices E and F, contains the load-displacement curves and photographs of the fracture toughness specimens from the 72W weld (0.23 wt % Cu) and the 73 W weld (0.31 wt % Cu), respectively.
Date: October 1, 1992
Creator: Nanstad, R. K.; Haggag, F. M.; McCabe, D. E.; Iskander, S. K.; Bowman, K. O. & Menke, B. H.
Partner: UNT Libraries Government Documents Department

Effects of irradiation on initiation and crack-arrest toughness of two high-copper welds and on stainless steel cladding

Description: The objective of the study on the high-copper welds is to determine the effect of neutron irradiation on the shift and shape of the ASME K{sub Ic} and K{sub Ia} toughness curves. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Compact specimens fabricated from these welds were irradiated at a nominal temperature of 288{degree}C to fluences from 1.5 to 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). The fracture toughness test results show that the irradiation-induced shifts at 100 MPa/m were greater than the Charpy 41-J shifts by about 11 and 18{degree}C. Mean curve fits indicate mixed results regarding curve shape changes, but curves constructed as lower boundaries to the data do indicate curves of lower slopes. A preliminary evaluation of the crack-arrest results shows that the neutron-irradiation induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower bound curves (for the range of test temperatures covered), compared to those of the ASME K{sub Ia} curve did not appear to have been altered by the irradiation. Three-wire stainless steel weld overlay cladding was irradiated at 288{degree}C to fluences of 2 and 5 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). Charpy 41-J temperature shifts of 13 and 28{degree}C were observed, respectively. For the lower fluence only, 12.7-mm thick compact specimens showed decreases in both J{sub Ic} and the tearing modulus. Comparison of the fracture toughness results with typical plate and a low upper-shelf weld reveals that the irradiated stainless steel cladding possesses low ductile initiation fracture toughness comparable to the low upper-shelf weld. 8 refs., 12 figs., 2 tabs.
Date: January 1, 1990
Creator: Nanstad, R.K.; Iskander, S.K. & Haggag, F.M.
Partner: UNT Libraries Government Documents Department

Direct comparison of unloading compliance and potential drop techniques in J-integral testing

Description: Single-specimen J-integral testing is performed commonly with the unloading compliance technique. Use of modern instrumentation techniques and powerful desktop computers have made this technique a standard. However, this testing technique is slow and tedious, with the loading rate fixed at a slow quasi-static rate. For these reasons the dc potential drop technique was investigated for crack length measurement during a J-integral test. For direct comparison, both unloading compliance and potential drop were used simultaneously during a J-integral test. The results showed good agreement between the techniques. However, the potential drop technique showed an offset in crack length due to plastic blunting processes. Taking this offset into account, J/sub Ic/ values calculated by both techniques compared well.
Date: January 1, 1984
Creator: McGowan, J.J. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR plants

Description: Recent data from the HFIR vessel surveillance program indicate a substantial radiation embrittlement rate effect at low irradiation temperatures (/approximately/120/degree/F) for A212-B, A350-LF3, A105-II, and corresponding welds. PWR vessel supports are fabricated of similar materials and are subjected to the same low temperatures and fast neutron fluxes (10/sup 8/ to 10/sup 9/ neutrons/cm/sup 2//center dot/s, E > 1.0 MeV) as those in the HFIR vessel. Thus, the embrittlement rate of these structures may be greater than previously anticipated. A study sponsored by the NRC is under way at ORNL to determine the impact of the rate effect on PWR vessel-support life expectancy. The scope includes the interpretation and application of the HFIR data, a survey of all light-water-reactor vessel support designs, and a structural and fracture-mechanics analysis of the supports for two specific PWR plants of particular interest with regard to a potential for support failure as a result of propagation of flaws. Calculations performed thus far indicate best-estimate critical flaw sizes, corresponding to 32 EFPY, of /approximately/0.2 in. for one plant and /approximately/0.4 in. for the other. These flaw sizes are small enough to be of concern. However, it appears that low-cycle fatigue is not a viable mechanism for creation of flaws of this size, and thus, presumably, such flaws would have to exist at the time of fabrication. 59 refs., 128 figs., 49 tabs.
Date: January 1, 1989
Creator: Cheverton, R.D.; Pennell, W.E.; Robinson, G.C. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Impact of radiation embrittlement on integrity of pressure vessel supports for two PWR (pressurized-water-reactor) plants

Description: Recent pressure-vessel surveillance data from the High Flux Isotope Reactor (HFIR) indicate an embrittlement fluence-rate effect that is applicable to the evaluation of the integrity of light-water reactor (LWR) pressure vessel supports. A preliminary evaluation using the HFIR data indicated increases in the nil ductility transition temperature at 32 effective full-power years (EFPY) of 100 to 130/degree/C for pressurized-water-reactor (PWR) vessel supports located in the cavity at midheight of the core. This result indicated a potential problem with regard to life expectancy. However, an accurate assessment required a detailed, specific-plant, fracture-mechanics analysis. After a survey and cursory evaluation of all LWR plants, two PWR plants that appeared to have a potential problem were selected. Results of the analyses indicate minimum critical flaw sizes small enough to be of concern before 32 EFPY. 24 refs., 16 figs., 7 tabs.
Date: January 1, 1988
Creator: Cheverton, R.D.; Pennell, W.E.; Robinson, G.C. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Observations on the behavior of surface flaws in the presence of cladding

Description: A small crack near the inner surface of clad nuclear reactor pressure vessels (RPV) is an important consideration in the safety assessment of the structural integrity of the vessel. Four-point bend tests on large plate specimens, six clad and two unclad, were performed to determine the effect, if any, of stainless steel cladding upon the propagation of small surface cracks subjected to stress states similar to those produced by pressurized thermal shock conditions. Results of tests at temperature 10 and 60/degree/C below the nil-ductility-transition temperature (NDT) have shown that (1) a tough surface layer composed of cladding and/or heat-affected zone has arrested running flaws in clad plates under conditions where unclad plates have ruptured, and (2) the residual load-bearing capacity of clad plates with large subclad flaws significantly exceeded that of an unclad plate. 6 refs., 7 figs., 2 tabs.
Date: January 1, 1988
Creator: Iskander, S.K. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Irradiation effects in low-alloy reactor pressure vessel steels (Heavy-Section Steel Technology Program Series 4 and 5)

Description: Multiple testing is done at two laboratories of typical nuclear pressure vessel materials (both irradiated and unirradiated) and statistical analyses of the test results. Multiple tests are conducted at each of several test temperatures for each material, standard deviations are determined, and results from the two laboratories are compared. The Fourth Heavy-Section Steel Technology (HSST) Irradiation Series, almost completed, was aimed at elastic-plastic and fully plastic fracture toughness of low-copper weldments (current practice welds). A typical nuclear pressure vessel plate steel was included for statistical purposes. The Fifth HSST Irradiation Series, now in progress, is aimed at determining the shape of the K/sub IR/ curve after significant radiation-induced shift of the transition temperatures. This series includes irradiated test specimens of thicknesses up to 100 mm and weldment compositions typical of early nuclear power reactor pressure vessel welds.
Date: January 1, 1984
Creator: Berggren, R.G.; McGowan, J.J.; Menke, B.H.; Nanstad, R.K. & Thoms, K.R.
Partner: UNT Libraries Government Documents Department

Charpy toughness and tensile properties of a neutron irradiated stainless steel submerged-arc weld cladding overlay

Description: The possibility of stainless steel cladding increasing the resistance of an operating nuclear reactor pressure vessel to extension of surface flaws is highly dependent upon the irradiated properties of the cladding. Therefore, weld overlay cladding irradiated at temperatures and fluences relevant to power reactor operation was examined. The cladding was applied to a pressure vessel steel plate by the submerged-arc, single-wire, oscillating electrode method. Three layers of cladding were applied to provide a cladding thickness adequate for fabrication of test specimens. The first layer was type 309, and the upper two layers were type 308 stainless steel. There was considerable dilution of the type 309 in the first layer of cladding as a result of excessive melting of the base plate. Specimens for the irradiation study were taken from near the base plate/cladding interface and also from the upper layers of cladding. Charpy V-notch and tensile specimens were irradiated at 288/sup 0/C to neutron fluences of 2 x 10/sup 23/ n/m/sup 2/ (E > 1 MeV). When irradiated, both types 308 and 309 cladding showed a 5 to 40% increase in yield strength accompanied by a slight increase in ductility in the temperature range from 25 to 288/sup 0/C. All cladding exhibited ductile-to-brittle transition behavior during impact testing.
Date: January 1, 1984
Creator: Corwin, W.R.; Berggren, R.G. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Characterization of four prestressed concrete reactor vessel liner steels

Description: A program of fracture toughness testing and analysis is being performed with PCRV steels for HTGRs. This report focuses on background information for the base materials and results of characterization testing, such as tensile and impact properties, chemical composition, and microstructural examination. The steels tested were an SA-508 class 1 forging, two plates of SA-537 class 1, and one plate of SA-537 class 2. Tensile requirements in effect at the time of procurement are met by all four steels. However, the SA-537 class 2 plate would not meet the minimum requirement for yield strength. Drop-weight and Charpy impact tests verified that the RT/sub NDT/ is equal to the NDT for each steel. Charpy impact energies at the NDT range from 40 J (30 ft-lb) for one heat of SA-537 class 1 to 100 J (74 ft-lb) for the SA-537 class 2 plate; upper-shelf energies range from 170 to 310 J (125 to 228 ft-lb) for the same two steels, respectively. The onset of upper-shelf energy occurred at temperatures ranging from 0 to 50/sup 0/C.
Date: December 1, 1980
Creator: Nanstad, R. K.
Partner: UNT Libraries Government Documents Department

The effect of aging at 343 degrees C on type 308 stainless steel weldments

Description: The effect of long-term aging at intermediate temperatures on the mechanical properties of stainless steel welds has been studied. Three type 308 multipass shielded metal-arc welds with ferrite levels of 4, 8, and 12% were aged up to 343{degrees}C. Tensile tests showed little effect of aging on either the yield or ultimate tensile strengths, but the impact toughness was significantly degraded. The extent of the degradation increased with increasing ferrite content and increasing aging time. Examination of the microstructure with transmission electron microcscopy and atom probe field-ion microscopy revealed that the ferrite phase had undergone spinodal decomposition as a result of aging. In addition, G-phase particles were observed at dislocations, and finer G-phase particles were homogeneously distributed throughout the ferrite phase. The changes in the mechanical properties and the fractography are discussed in light of the observed changes in the microstructure. 19 refs., 7 figs., 2 tabs.
Date: January 1, 1990
Creator: Alexander, D.J.; Alexander, K.B.; Miller, M.K. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Evaluation of fracture models through pressurized-thermal-shock testing

Description: Two multiple-transient pressurized-thermal-shock experiments (PTSEs) have been conducted under the NRC-sponsored Heavy-Section Steel Technology (HSST) program. The first test (PTSE-1) employed an SA-508 class 2 steel with high Charpy upper-shelf energy level and a relatively high brittle-to-ductile transition temperature. The second test (PTSE-2) used a 2 1/4 Cr-1 Mo steel (SA-387 grade 22) that had been given a special heat treatment to yield a low Charpy upper-shelf energy level and attendant low tearing resistance. Each experiment included two combined thermal and pressure transients that give rise to propagation and arrest of an initial long flaw that extended about 10% through the thick wall of the test cylinder. Both materials exhibited the ability to inhibit crack propagation by warm prestressing, high initiation toughness values and high crack-arrest toughness values. Cleavage initiation and arrest are modeled well by available fracture theories. However, calculations of ductile tearing based on resistance curves did not consistently predict the observed tearing.
Date: January 1, 1988
Creator: Pugh, C.E.; Bryan, R.H.; Bass, B.R. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Chemical composition and RT[sub NDT] determinations for Midland weld WF-70

Description: The Heavy-Section Steal Irradiation Program Tenth Irradiation Series has the objective to investigate the affects of radiation on the fracture toughness of the low-upper-shelf submerged-arc welds (B W designation WF-70) in the reactor pressure vessel of the canceled Midland Unit 1 nuclear plant. This report discusses determination of variations in chemical composition And reference temperature (RT[sub NDT]) throughout the welds. Specimens were machined from different sections and through thickness locations in both the beltline and nozzle course welds. The nil-ductility transition temperatures ranged from [minus]40 to [minus]60[degrees]C ([minus]40 and [minus]76[degrees]F) while the RT[sub NDT]S, controlled by the Charpy behavior, varied from [minus]20 to 37[degrees]C ([minus]4 to 99[degrees]F). The upper-shelf energies varied from 77 to 108 J (57 to 80 ft-lb). The combined data revealed a mean 41-J (30-ft-lb) temperature of [minus]8[degrees]C (17[degrees]F) with a mean upper-shelf energy of 88 J (65 ft-lb). The copper contents range from 0.21 to 0.34 wt % in the beltline weld and from 0.37 to 0.46 wt % in the nozzle course weld. Atom probe field ion microscope analyses indicated substantial depletion of copper in the matrix but no evidence of copper clustering. Statistical analyses of the Charpy and chemical composition results as well as interpretation of the ASME procedures for RT[sub NDT] determination are discussed.
Date: December 1, 1992
Creator: Nanstad, R.K.; McCabe, D.E.; Swain, R.L. & Miller, M.K. (Oak Ridge National Lab., TN (United States))
Partner: UNT Libraries Government Documents Department

Irradiation effects in low-alloy reactor pressure vessel steels (Heavy-Section Steel Technology program series 4 and 5)

Description: This report presents studies on the irradiation effects in low-alloy reactor pressure vessel steels. The Fourth Heavy-Section Steel Technology (HSST) Irradiation Series, almost completed, was aimed at elastic-plastic and fully plastic fracture toughness of low-copper weldments (''current practice welds''). A typical nuclear pressure vessel plate steel was included for statistical purposes. The Fifth HSST Irradiation Series, now in progress, is aimed at determining the shape of the K/sub IR/ curve after significant radiation-induced shift of the transition temperatures. This series includes irradiated test specimens of thicknesses up to 100 mm and weldment compositions typical of early nuclear power reactor pressure vessel welds. 27 refs., 22 figs. (JDB)
Date: January 1, 1985
Creator: McGowan, J.J.; Nanstad, R.K.; Thoms, K.R. & Menke, B.H.
Partner: UNT Libraries Government Documents Department

The use of field indentation microprobe in measuring mechanical properties of welds

Description: A field indentation microprobe (FIM) was conceived for evaluating the structural integrity of metallic components (including base metal, welds, and heat-affected zones) in situ in a nondestructive manner. The FIM consists of an automated ball indentation (ABI) unit for determining the mechanical properties (yield strength, flow properties, estimates of fracture toughness, etc.) and a nondestructive evaluation (NDE) unit (consisting of ultrasonic transducers and a video camera) for determining the physical properties such as crack size, material pileup around indentation, and residual stress presence and orientation. The laboratory version used in this work performs only ABI testing. ABI tests were performed on stainless steel base metal (type 316L), heat-affected zone, and welds (type 308). Excellent agreement was obtained between yield strength and flow properties (true-stress/true-plastic-strain curve) measured by the ABI tests and those from uniaxial tensile tests conducted on 308 stainless steel welds, thermally aged at 343/degree/C for different times, and on the base material. 4 refs., 17 figs.
Date: January 1, 1989
Creator: Haggag, F.M.; Wong, H.; Alexander, D.J. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

An experimental study of the effect of stainless steel cladding on the structural integrity of flawed steel plates in bending

Description: A small crack near the inner surface of clad nuclear reactor pressure vessels is an important consideration in the safety assessment of the structural integrity of the vessel. Experimental results from tests on large clad and unclad plate specimens with surface flaws have shown that (1) a tough surface layer composed of cladding and/or heat-affected zone has arrested running flaws in clad plates under conditions where unclad plates have ruptured, and (2) the residual load-bearing capacity of clad plates with large subclad flaws significantly exceeded that of an unclad plate. The fracture surfaces of unclad plates suggest that the flaw evolves through alternately tunneling then breaking to the surface. In the case of clad plates, it is hypothesized that the tough, strong surface layer inhibits the tunneled flaw from propagating to the surface.
Date: January 1, 1989
Creator: Iskander, S.K.; Nanstad, R.K.; Robinson, G.C. & Oland, C.B.
Partner: UNT Libraries Government Documents Department

The effect of aging at 343/degree/C on type 308 stainless steel welds

Description: Three nominally 25-mm (1-in) thick shielded metal-arc welds were prepared from 304L base plate with 308 filler material, to obtain three different ferrite levels (4, 8, and 12 %). Portions of these welds were then aged at 343/degree/C for 3000, 10000, and 20000 hours. Charpy V-notch and tensile specimens were taken from the welds. The tensile results were similar for all the specimens and showed little effect of aging on either the yield or ultimate tensile strengths. The Charpy impact properties of the higher ferrite content materials were significantly degraded by these agings, with larger decreases in the impact energy with increased aging time. The microstructures of the welds were examined by metallography and transmission electron microscopy, and the fracture surfaces were examined by scanning electron microscopy. The changes in the mechanical properties and the fractography are discussed in light of the observed changes in the microstructure. 3 refs., 3 figs., 2 tabs.
Date: January 1, 1989
Creator: Alexander, D.J.; Alexander, K.B. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department

Effects of irradiation on K/sub Ic/ curves for high-copper welds

Description: The Fifth Irradiation Series in the Heavy-Section Steel Technology (HSST) Program is aimed at obtaining a statistically significant fracture toughness data base on two weldments with high-copper contents to determine the shift and shape of the K/sub Ic/ curve as a consequence of irradiation. The program includes irradiated Charpy V-notch impact, tensile, and drop-weight specimens in addition to compact fracture toughness specimens. Compact specimens (CS) with thicknesses of 25.4, 50.8, and 101.6 mm (1TCS, 2TCS, and 4TCS, respectively) have been irradiated. Additionally, unirradiated 6TCS and 8TCS have been tested to attain the same K/sub Ic/ measuring capacity as the irradiated specimens. The materials for this irradiation series are two weldments fabricated from special heats of weld wire with copper added to the melt. One lot of Linde 0124 flux was used for all the welds. Copper levels for the two welds are 0.23 and 0.31 wt %, while the nickel contents are 0.60 wt %. 17 refs., 16 figs., 9 tabs.
Date: January 1, 1988
Creator: Nanstad, R.K.; McCabe, D.E.; Menke, B.H.; Iskander, S.K. & Haggag, F.M.
Partner: UNT Libraries Government Documents Department

Effects of 50/degree/C surveillance and test reactor irradiations on ferritic pressure vessel steel embrittlement

Description: The results of surveillance tests on the High-Flux Isotope Reactor (HFIR) pressure vessel at the Oak Ridge National Laboratory revealed that a greater than expected embrittlement had taken place after about 17.5 effective full-power years of operation and an operational assessment program was undertaken to fully evaluate the vessel condition and recommend conditions under which operation could be resumed. A research program was undertaken that included irradiating specimens in the Oak Ridge Research Reactor. Specimens of the A212 grade B vessel shell material were included, along with specimens from a nozzle qualification weld and a submerged-arc weld fabricated at ORNL to reproduce the vessel seam weld. The results of the surveillance program and the materials research program performed in support of the evaluation of the HFIR pressure vessel are presented and show the welds to be more radiation resistant than the A212B. Results of irradiated tensile and annealing experiments are described as well as a discussion of mechanisms which may be responsible for enhanced hardening at low damage rates. 20 refs., 22 figs., 5 tabs.
Date: January 1, 1988
Creator: Nanstad, R.K.; Iskander, S.K.; Rowcliffe, A.F.; Corwin, W.R. & Odette, G.R.
Partner: UNT Libraries Government Documents Department

Effects of irradiation on crack-arrest toughness of two high-copper welds

Description: The objective of this study is to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288{degree}C to an average fluence of 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). A preliminary evaluation of the results shows that the neutron-irradiation induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves, (for the range of test temperatures covered), compared to those of the ASME K{sub Ia}-curve did not seem to have been altered by irradiation. 10 refs., 9 figs., 7 tabs.
Date: January 1, 1990
Creator: Iskander, S.K.; Corwin, W.R. & Nanstad, R.K.
Partner: UNT Libraries Government Documents Department