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Preliminary cleaning tests on candidate materials for APS beamline and front end UHV components

Description: Comparative cleaning tests have been done on four candidate materials for use in APS beamline and front-end vacuum components. These materials are 304 SS, 304L SS, OFHC copper, and Glidcop* (Cu-Al{sub 2}O{sub 3})- Samples of each material were prepared and cleaned using two different methods. After cleaning, the sample surfaces were analyzed using ESCA (Electron Spectography for Chemical Analysis). Uncleaned samples were used as a reference. The cleaning methods and surface analysis results are further discussed.
Date: May 12, 1992
Creator: Nielsen, R. & Kuzay, T.M.
Partner: UNT Libraries Government Documents Department

Feasibility of eddy current measurement of ferrite content in stainless steel welds

Description: A phase-sensitive eddy current system was used to measure the presence of ferrite in an austenitic stainless steel matrix. Measurements were made on pressed powder specimens and on a weld in Type 304L stainless steel. The data obtained showed that small amounts of ferrite, on the order of 1 to 3%, could easily be detected. Variation in ferrite with position within the weld was also detected with good reproducibility. Absolute values for the ferrite content were not obtained as accurate standards for calibration were not available. (auth)
Date: December 17, 1973
Creator: Lassahn, G. D. & Moment, R. L.
Partner: UNT Libraries Government Documents Department

Determination of residual stresses by local annealing to laser speckle pattern interferometry

Description: One of the most common methods of experimentally determining residual stresses is Blind Hole Drilling (BHD). A new method which is a thermo-optical analog to BHD is being developed. This method uses local heating to anneal a tiny spot and uses laser speckle interferometry to measure the strain that results. This strain is used to determine the state of stress prior to heating. The peak temperatures are on the order of 200 Celsius so that for most metals, there will be no changes in phase or other material properties except for a slight reduction in yield stress. Preliminary experiments with type 304 stainless steel were performed using resistance heating. The experimental results were in excellent agreement with finite element model predictions of the process. Subsequently, the resistance heating was replaced with laser heating. The heat input (22.5 Watt peak) from a small sealed radio frequency excited Carbon Dioxide laser was used. In order to both control the heating temperature and efficiently couple the infrared photons from the laser into the test specimen, a substance known as Liquid Temperature Indicating Paint was used. Without this substance the laser power would be so large as to make this approach impractical. Furthermore the measurement and control for the heat input would be very complicated. Using this laser heating approach was successful in obtaining similar results to those obtained in other work. Since this laser based technique is a thermo-optical analog to blind hole drilling a simple stress model is required to interpret the measured results. This simple stress model is presented. As in BHD, the simple model must be modified by empirical coefficients to be useful. These empirical coefficients are determined by experimentation and/or numerical analysis
Date: May 1, 1997
Creator: Pechersky, M. & Vikram, C.S.
Partner: UNT Libraries Government Documents Department

The effects of 800 MeV proton irradiation on the corrosion of tungsten, tantalum, stainless steel, and gold

Description: Real time electrochemical data were acquired for tungsten, tantalum, stainless steel 304L, and gold targets during proton irradiation at the LANSCE Weapons Neutron Research Facility. The goal of this research was to establish a better understanding of the corrosion properties of materials as a function of proton irradiation and gain insight into the mechanism of the observed phenomena. The following electrochemical observations were made during proton irradiation of W, Ta, SS304, and Au: (1) the open circuit potential of all materials increased with increasing proton fluence; (2) the corrosion rate (at the OCP) of W and SS304 increased with increasing proton fluence; (3) the passive dissolution rate for SS304 and Ta decreased with increasing proton fluence; (4) the anodic dissolution rate for W increased with increasing proton fluence; (5) the pitting potential for SS304 increased with proton fluence, which is an indication that the material is less susceptible to pitting attack during irradiation.
Date: December 1, 1997
Creator: Lillard, R.S.; Butt, D.P.; Kanner, G. & Daemen, L.
Partner: UNT Libraries Government Documents Department

External Corrosion Analysis of Model 9975 Packaging Container

Description: The Materials Consultation Group of SRTC has completed an external corrosion analysis of the Model 9975 packaging container for storage in K Reactor under ambient conditions for a period of 12 years. The 12-year storage period includes two years for shipping and ten years for storage. Based on review of existing literature and stated building storage conditions, corrosion degradation of the 304L Stainless Steel (SS) packaging container (drum and vessels) should be minimal during the 12 year time period. There may be visible corrosion on the galvanized carbon steel pallet due to initial drum handling. The visible corrosion will not be sufficient to cause significant degradation during the 12-year storage period. The Materials Consultation Group concludes that there are sufficient data to establish the technical basis for safe storage of the Model 9975 container in the 105-K building for up to 10 years following the 2-year shipping period. The data are sufficient to allow the 304L SS containers to be stored for a total period of 15 years.
Date: February 23, 1999
Creator: Vormelker, P.
Partner: UNT Libraries Government Documents Department

Electrodissolution studies of 304 stainless steel in sodium nitrate electrolyte

Description: To explore the impact of a wide range of operating parameters upon 304 stainless steel (SS) dissolution in sodium nitrate (NaNO{sub 3}) electrolyte, the staff of Engineering Science Applications-Energy and Process Engineering performed a series of beaker experiments. The variables that the authors explored included NaNO{sub 3} concentration, chromate concentration, pH, stirring rate, and current density. They adjusted the run length to obtain approximately 10 mg/cm{sup 2} metal removal so that they could compare surface finishes under similar test conditions. Key findings may be summarized as follows. Current efficiency during dissolution depends most strongly upon current density and electrolyte concentration. At 0.05 A/cm{sup 2}, current density is more dependent upon chromium concentration than they previously thought. They obtained the best surface finish in a classical electropolishing regime at current densities above 1.5 A/cm{sup 2}. Mirror-like finishes were obtained at near 100% current efficiency. At 0.05 a/cm{sup 2} they obtained reasonable surface finishes, particularly at lower electrolyte concentration. Current efficiency was low (30%). At intermediate current densities, they obtained the worst surface finishes, that is, surfaces with severe pitting. Also, they explored preferential attack of the weld zone during electrodissolution of 304 stainless steel cans. Electrodissolution removed approximately twice as much material from cans with unshielded weld zones as from cans with shielded weld zones. The following implications are apparent. While operation above 1 A/cm{sup 2} yields the best surface finish at 100% current efficiency, equipment size and power feedthrough limitations reduce the attractiveness of this option. Because other Los Alamos researchers, obtained more favorable results with the sulfate electrolyte, the authors recommend no further work for the sodium nitrate electrolyte system.
Date: December 1, 1997
Creator: Weisbrod, K.R.; Trujillo, V.L. & Martinez, H.E.
Partner: UNT Libraries Government Documents Department

Sealing 304L to lithia-alumina-silica (LAS) glass-ceramics

Description: The formation of a crack-free between 300 series stainless steel and a glass-ceramic is difficult owing to the high coefficients of thermal expansion of the stainless steels. Lithia-alumina-silica (LAS) glass-ceramics were successfully developed and sealed to 304L stainless steel. These crack-free seals were fabricated by two techniques: by adjusting the parent glass composition (reducing the Al{sub 2}O{sub 3} content), or by adjusting the sealing/crystallization cycle. All seals were hermetic, with leak rates < 10{sup -8} cc/sec STP helium. CTE and alloy yield strengths are given which show the feasibility of using these materials to make feedthroughs, pyrotechnic components, etc. Metallography, SEM, and wavelength dispersive spectroscopy show the quality and integrity of the glass-ceramic/stainless steel interface. These data are compared to those on the Inconel 718/LAS-glass seal system.
Date: December 31, 1989
Creator: Moddeman, W.E.; Pence, R.E.; Massey, R.T.; Cassidy, R.T. & Kramer, D.P.
Partner: UNT Libraries Government Documents Department

Stage 1 behavior in a stress corrosion study of Type 304 stainless steel

Description: In stress corrosion studies, crack velocity plotted with respect to stress intensity generally yields a characteristic curve with three distinct regions. Stage I exhibits a threshold (K{sub ISCC}) followed by a rapid increase in crack velocity (da/dt) for small changes in stress intensity. Stage II is characterized by an essentially constant crack velocity with increases in the stress intensity. Stage III exhibits a rapid increase in crack velocity for small increases in stress intensity leading to fracture. Stage I behavior has been poorly characterized in literature due to previous emphasis on determining the threshold K{sub ISCC} and difficulty and uncertainty in measuring of a large increase in crack velocity with only incremental changes in stress intensity. Tests were conducted in the stage I regime to measure crack velocity as a function of constant stress intensity. Constant K specimens were prepared according to the Mostovoy design, (a tapered double cantilever beam). Specimens were prepared from Type 304 stainless steel containing 0.06 wt% C solution annealed at 1100C for 1 hour, water quenched, and annealed at 625C for 24 hours to produce sensitization. A sodium thiosulfate solution at 50{degree}C was chosen as the test environment.
Date: March 1, 1994
Creator: Lund, A. L. & Jones, R. H.
Partner: UNT Libraries Government Documents Department

Investigation of residual stresses in a multipass weld in 1 in. stainless steel plate

Description: Residual stresses and strains were measured in two welded 25-mm thick plates of type 304 stainless steel by the neutron diffraction. The filler metal was type 308 stainless steel and the weld zone had a two phase microstructure in which the austenitic phase lattice parameter differs from the base metal. In these circumstances stain-free samples were taken from the weld zone area for analysis of the lattice parameters and ferrite content using neutron powder diffraction. Corrections for lattice parameter variation were applied permitting the calculation of residual strains and stresses in weld zone, heat affected zone (HAZ) and base metal. One of the two welds was examined without stress relief and the other was given a stress relief treatment consisting of vibration at a frequency below the resonant condition dudng welding. In both plates the largest residual stress component (longitudinal) is found in the fusion zone near the boundary between the weld zone and the heat affected zone. This longitudinal component is 400 {plus_minus} 50 MPa in tension. The normal stresses are generally close to zero although large fluctuations are found in the weld zone. The transverse stresses are as high as 200 MPa in the weld zone and decrease to 50 MPa {plus_minus} 40 MPa. The lattice parameter variation was equivalent to 5 {times} l0{minus}4 compressive strain and the ferrite content approached 9 percent at the center of the weld zone. Variations in residual stresses with thickness through the base metal plate were small. The treated plate and untreated plate showed nearly identical patterns of stress distribution. Differences in the measured stresses between vibratory-stress-relief treated and untreated plates fall within error bars of the stress determination in these particular 25 mm thick 300-type stainless steel plates.
Date: June 1, 1994
Creator: Spooner, S.; Fernandez Baca, J. A.; David, S. A.; Hubbard, C. R.; Holden, T. M. & Root, J. H.
Partner: UNT Libraries Government Documents Department

Supplementary safety system corrosion studies

Description: This memorandum presents experimental data from electrochemical and immersion tests to support the continued use of two sections of nonconforming steel in the Supplementary Safety System. The Reactor Corrosion Mitigation Committee met on May 16, 1991 to evaluate materials that had been installed in the SSS. The materials lacked complete Corrosion Evaluation (CE) and/or Certified Mill Test Reports and had been installed during recent modifications (Project S-4332). Items that lacked proper documentation included AISI Type 304 stainless steel (304) instrument tubing (0.375`` OD) associated with the pressure transmitters and a two-foot section of 304 pipe located on the far side of the system downstream of the pneumatic valves. Cyclic potentiodynamic polarization scans were performed on sensitized and solution-annealed 304 samples in as-mixed and acidified Gd(NO{sub 3}){sub 3}, or ``ink``, solutions at room temperature to determine the susceptibility of 304 to localized corrosion in this environment. No localized attack was observed on the solution annealed or sensitized 304 in the Gd(NO{sub 3}){sub 3} solution. These tests revealed no significant differences in the behavior of the sensitized and solution-annealed 304 in gadolinium nitrate solution. Therefore, localized corrosion of the nonconforming components is not anticipated, and the performance of the nonconforming components should not differ from that of corrosion evaluated and certified materials. Previous studies have shown that AISI Type 304L stainless steel (304L) did not pit during a three-month exposure in gadolinium nitrate solutions of pH 2 or 5. These combined results support the continued use of the nonconforming steels until replacement can be made at the next scheduled long shut-down.
Date: May 21, 1991
Creator: Anderson, M. H. & Wiersma, B. J.
Partner: UNT Libraries Government Documents Department

A transmission electron microscopy evaluation of solid-state upset welds in Type 304L stainless steel

Description: Transmission electron microscopy (TEM) was used to characterize the microstructures at and near the weld interface in upset welded Type 304L stainless steel test samples. Two sample configurations were examined in this study; upset welded cylinders prepared using a commercial resistance welder and cylindrical shaped samples welded in a Gleeble 1500 thermomechanical simulation device. The Gleeble samples evaluated were welded at 800 C, 900 C and 1,200 C with a 0.5 cm weld upset. The base microstructure of the samples varied with weld temperature. The lower temperature specimens contained a large free-dislocation density and distinct dislocation cells. The higher temperature specimens contained well-developed subgrains and a much lower free-dislocation density. The microstructure of the upset welded samples most closely resembled the 1,200 C Gleeble sample. No distinct bond line was observed by TEM in any of the specimens, i.e., diffusion and grain growth occurred across all weld interfaces. However, weld interfaces in both specimen configurations were characterized by the presence of 50--300 nm diameter particles spaced between 300 and 1,300 nm apart. Through the use of electron diffraction analysis and X-ray microanalysis two precipitate types were identified in both specimen configurations. A crystalline phase very similar to Mn{sub 1.5}Cr{sub 1.5}O{sub 4} and an amorphous phase enriched mainly in Si and Al were observed. Surface oxides and/or internal impurities may be sources for these precipitates. Future work will include a controlled study designed to determine the origin of the interface precipitates.
Date: September 8, 1995
Creator: Tosten, M.H.
Partner: UNT Libraries Government Documents Department

Electrolytic decontamination of conductive materials for hazardous waste management

Description: Electrolytic removal of plutonium and americium from stainless steel and uranium surfaces has been demonstrated. Preliminary experiments were performed on the electrochemically based decontamination of type 304L stainless steel in sodium nitrate solutions to better understand the metal removal effects of varying cur-rent density, pH, and nitrate concentration parameters. Material removal rates and changes in surface morphology under these varying conditions are reported. Experimental results indicate that an electropolishing step before contamination removes surface roughness, thereby simplifying later electrolytic decontamination. Sodium nitrate based electrolytic decontamination produced the most uniform stripping of material at low to intermediate pH and at sodium nitrate concentrations of 200 g L{sup -1} and higher. Stirring was also observed to increase the uniformity of the stripping process.
Date: December 31, 1996
Creator: Wedman, D.E.; Martinez, H.E. & Nelson, T.O.
Partner: UNT Libraries Government Documents Department

Analysis of cracking of co-extruded recovery boiler floor tubes

Description: Cracking of the stainless steel layer in co-extruded 304L/SA210 tubing used in black liquor recovery boilers is being found in an ever-increasing number of North American pulp and paper mills. Because of the possibility of a tube failure, this is a significant safety issue, and, because of the extra time required for tube inspection and repair, this can become an economic issue as well. In a project funded by the U.S. Department of Energy and given wide support among paper companies, boiler manufacturers, and tube fabricators, studies are being conducted to determine the cause of the cracking and to identify alternate materials and/or operating procedures to prevent tube cracking. Examination of cracked tubes has permitted characterization of crack features, and transmission electron microscopy is providing information about the thermal history, particularly cyclic thermal exposures, that tubes have experienced. Neutron and x-ray diffraction techniques are being used to determine the residual stresses in as-fabricated tube panels and exposed tubes, and finite element modeling is providing information about the stresses the tubes experience during operation. Laboratory studies are being conducted to determine the susceptibility of the co-extruded 304L/SA210 tubes to stress corrosion cracking, thermal fatigue, and corrosion in molten smelt. This paper presents the current status of these studies. On the basis of all of these studies, recommendations for means to prevent tube cracking will be offered.
Date: August 1, 1997
Creator: Keiser, J.R.; Taljat, B. & Wang, X.L.
Partner: UNT Libraries Government Documents Department

Application of internal state variable plasticity and damage models to welding

Description: An internal state variable constitutive model coupled with a ductile void growth model is applied in two finite element simulations of welding. Shrinkage of a 304 L stainless steel pipe due to multipass gas tungsten arc welds is presented as an example of tracking distortion far from the weld. Weld solidification cracking in Al-6061 disks is presented as an application of the plasticity model coupled with the damage model.
Date: June 1, 1997
Creator: Dike, J.J.; Ortega, A.R.; Bammann, D.J. & Lathrop, J.F.
Partner: UNT Libraries Government Documents Department

Texture and yield stress of pre-strained 304L stainless steel

Description: The evolution of texture and yield stress in 304L stainless steel is investigated as a function of deformation to large plastic strains. Steel bars quasi-statically upset forged at a strain rate of 0.001 s{sup {minus}1} to true strains of 0, 0.5, 1.0 and 1.8 were found to acquire their texture ({approximately}3.0 m.r.d.) in the first 0.5 strain with (110) poles highly aligned parallel to the compression direction independent of whether the pre-forged starting material was in a cold worked or annealed (1,050 C for 1 hour) condition. The same bars, when strained at room temperature show an incremental yield with pre-strain regardless of strain rate (10{sup {minus}1} or 10{sup {minus}3}s{sup {minus}1}) or thermal history, though annealed bars yield at slightly lower stresses. At 77 K and strain rate 10{sup {minus}3}s{sup {minus}1}, the annealed 304L exhibits more pronounced strain-hardening behavior than the 304L forged in a cold-worked condition.
Date: August 1, 1998
Creator: Bennett, K.; Dreele, R.B. von; Gray, G.T. III & Chen, S.R.
Partner: UNT Libraries Government Documents Department

Material Corrosion and Plate-Out Test of Types 304L and 316L Stainless Steel

Description: Corrosion and plate-out tests were performed on 304L and 316L stainless steel in pretreated Envelope B and Envelope C solutions. Flat coupons of the two stainless steels were exposed to 100 degrees C liquid and to 74 degrees C and 88 degrees C vapor above the solutions for 61 days. No significant corrosion was observed either by weight-loss measurements or by microscopic examination. Most coupons had small weight gains due to plate-out of solids, which remained to some extent even after 24-hour immersion in 1 N nitric acid at room temperature. Plate-out was more significant in the Envelope B coupons, with film thickness from less than 0.001 in. to 0.003-inches.
Date: February 6, 2001
Creator: Zapp, P.E.
Partner: UNT Libraries Government Documents Department

Analysis and validation of laser spot weld-induced distortion

Description: Laser spot welding is an ideal process for joining small parts with tight tolerances on weld size, location, and distortion, particularly those with near-by heat sensitive features. It is also key to understanding the overlapping laser spot seam welding process. Rather than attempting to simulate the laser beam-to-part coupling (particularly if a keyhole occurs), it was measured by calorimetry. This data was then used to calculate the thermal and structural response of a laser spot welded SS304 disk using the finite element method. Five combinations of process parameter values were studied. Calculations were compared to experimental data for temperature and distortion profiles measured by thermocouples and surface profiling. Results are discussed in terms of experimental and modeling factors. The authors then suggest appropriate parameters for laser spot welding.
Date: December 9, 1999
Creator: Knorovsky, G.A.; Kanouff, M.P.; Maccallum, D.O. & Fuerschbach, P.W.
Partner: UNT Libraries Government Documents Department

Microstructures of laser deposited 304L austenitic stainless steel

Description: Laser deposits fabricated from two different compositions of 304L stainless steel powder were characterized to determine the nature of the solidification and solid state transformations. One of the goals of this work was to determine to what extent novel microstructure consisting of single-phase austenite could be achieved with the thermal conditions of the LENS [Laser Engineered Net Shape] process. Although ferrite-free deposits were not obtained, structures with very low ferrite content were achieved. It appeared that, with slight changes in alloy composition, this goal could be met via two different solidification and transformation mechanisms.
Date: May 22, 2000
Partner: UNT Libraries Government Documents Department

A powder metallurgy approach for production of innovative radioactive waste forms

Description: The feasibility of producing a single metal-matrix composite form rather than two separate forms consisting of a cast metal alloy ingot (such as Type 316SS + Zr) and a ceramic glass-bonded zeolite Na{sub 12}(AlO{sub 2}){sub 12}(SiO{sub 2}){sub 12} has been demonstrated. This powder metallurgy approach consists of mixing the powder of the two separate waste forms together followed by compaction by hot isostatic pressing. Such a radioactive waste form would have the potential advantages of reducing the total waste volume, good thermal conductivity, stability, and surfaces with limited oxide layer formation. 5 refs., 8 figs., 2 tabs.
Date: July 1, 1997
Creator: Keiser, D.D. Jr.; Crawford, D.C. & Bhaduri, S.
Partner: UNT Libraries Government Documents Department

Laser-produced plasma measurement of thermal diffusivity of molten metals

Description: We have shown that a laser-produced plasma plume which is representative in composition of the condensed phase target can be reproducibly generated if the movement of the surface due to evaporation is kept in pace with the thermal diffusion front propagating into the bulk. The resulting mass loss is then strongly controlled by the thermal diffusivity of the target matter, and this relationship has been exploited to measure the thermal diffusivity of metallic alloys. We have developed a novel RF levitator-heater as a contamination-free molten metal source to be used as a target for LPP plume generation. In order to determine the mass loss due to LPP excitation, a new high sensitivity transducer has been constructed for measurement of the resulting impulse imparted on the specimen. The impulse transducer is built onto the specimen holder within the levitation-assisted molten metal source. The LPP method has been fully excercised for measurement of the thermal diffusivity of a molten specimen relative to the value for its room temperature solid. The results for SS304 and SS316 are presented together with a critique of the results. A numerical modeling of specimen heating in the molten metal source and the physical basis of the new hod are also presented.
Date: December 1995
Creator: Kim, Yong W. & Park, C. S.
Partner: UNT Libraries Government Documents Department

The effects of hydrogen on the fracture toughness properties of upset welded stainless steel

Description: The effects of hydrogen on the fracture toughness properties of upset welded Type 304L stainless steel were measured and compared to those measured previously for as-received and as-welded steels. The results showed that the upset welded steels had good fracture toughness properties, but values were lower than the as-received material. The fracture toughness value of the base material was 6420 in-lbs/sq. in., while the welded steels averaged 3660 in-lbs/sq. in. Hydrogen exposure lowered the fracture toughness values of the as-received steel by 43 % to 3670 in-lbs/sq. in. and the welded steels by 21 % to 2890 in-lbs/sq. in. The fracture morphologies of the unexposed steels showed that ductile fracture occurred by the microvoid nucleation and growth process. The size of the microvoids on the fracture surfaces of the welded steels were much smaller and more closely spaced that those found on the base material fracture surfaces. The change in the size and spacing of the microvoids indicates that the fracture toughness properties of the welded steels were lower than the base steels because of the higher concentration of microscopic precipitates on the weld plane. The welds examined thus far have been {open_quotes}good{close_quotes} welds and the presence of these precipitates was not apparent in standard {open_quotes}low{close_quotes}-magnification metallographic sections of the weld planes. The results indicate that hydrogen did not weaken greatly the solid-state welds but that other inclusions or impurities present prior to welding did. Improvements in surface cleaning and preparation prior to welding should be explored as a way to improve the strength of solid-state welded joints.
Date: June 1, 1995
Creator: Morgan, M.T.
Partner: UNT Libraries Government Documents Department