WorldWideScience

Sample records for waspaloy

  1. Creep Deformation by Dislocation Movement in Waspaloy.

    Science.gov (United States)

    Whittaker, Mark; Harrison, Will; Deen, Christopher; Rae, Cathie; Williams, Steve

    2017-01-12

    Creep tests of the polycrystalline nickel alloy Waspaloy have been conducted at Swansea University, for varying stress conditions at 700 °C. Investigation through use of Transmission Electron Microscopy at Cambridge University has examined the dislocation networks formed under these conditions, with particular attention paid to comparing tests performed above and below the yield stress. This paper highlights how the dislocation structures vary throughout creep and proposes a dislocation mechanism theory for creep in Waspaloy. Activation energies are calculated through approaches developed in the use of the recently formulated Wilshire Equations, and are found to differ above and below the yield stress. Low activation energies are found to be related to dislocation interaction with γ' precipitates below the yield stress. However, significantly increased dislocation densities at stresses above yield cause an increase in the activation energy values as forest hardening becomes the primary mechanism controlling dislocation movement. It is proposed that the activation energy change is related to the stress increment provided by work hardening, as can be observed from Ti, Ni and steel results.

  2. The role of cobalt on the creep of Waspaloy

    Science.gov (United States)

    Jarrett, R. N.; Chin, L.; Tien, J. K.

    1984-01-01

    Cobalt was systematically replaced with nickel in Waspaloy (which normally contains 13% Co) to determine the effects of cobalt on the creep behavior of this alloy. Effects of cobalt were found to be minimal on tensile strengths and microstructure. The creep resistance and the stress rupture resistance determined in the range from 704 to 760 C (1300 to 1400 C) were found to decrease as cobalt was removed from the standard alloy at all stresses and temperatures. Roughly a ten-fold drop in rupture life and a corresponding increase in minimum creep rate were found under all test conditions. Both the apparent creep activation energy and the matrix contribution to creep resistance were found to increase with cobalt. These creep effects are attributed to cobalt lowering the stacking fault energy of the alloy matrix. The creep resistance loss due to the removal of cobalt is shown to be restored by slightly increasing the gamma' volume fraction. Results are compared to a previous study on Udimet 700, a higher strength, higher gamma' volume fraction alloy with similar phase chemistry, in which cobalt did not affect creep resistance. An explanation for this difference in behavior based on interparticle spacing and cross-slip is presented.

  3. Residual stresses in laser direct metal deposited Waspaloy

    International Nuclear Information System (INIS)

    Moat, R.J.; Pinkerton, A.J.; Li, L.; Withers, P.J.; Preuss, M.

    2011-01-01

    Research highlights: → Neutron diffraction and the contour method show good agreement. → Tensile stresses found parallel to the surfaces. → Compressive stresses within the bulk of the structures. → Residual stress weakly dependent on the laser pulse parameters. → Maximum tensile residual stress unaffected across range of pulse parameters used. - Abstract: This paper reports a study into the effect of laser pulse length and duty cycle on the residual stress distributions in multi-track laser direct metal deposits of Waspaloy onto an Inconel 718 substrate. The residual stresses have been evaluated using neutron diffraction and the contour method, while electron microscopy and micro hardness indentation have been used to map the concomitant microstructural variation. In all cases, near the tops of the deposited walls, the longitudinal stresses are tensile towards the mid-length of the wall, while the stresses perpendicular to the substrate are negligible. By contrast near the base of the walls, the stresses along the direction of deposition are small, while the stresses perpendicular to the substrate are compressive at the centre and tensile towards the ends. Consistent with previous observations, the stresses parallel to free surfaces are tensile, balanced by compressive stresses in the interior (an inverse quench stress profile). These profiles have been found to be weakly dependent on the laser pulse parameters, most notably an increase in tensile stress gradient with increasing duty cycle, but the maximum residual stresses are largely unaffected. Furthermore, microstructural analysis has shown that the effect of laser pulse parameters on grain morphology in multi-track thick walls is less marked than previously reported for single-track wall structures.

  4. Residual stresses in laser direct metal deposited Waspaloy

    Energy Technology Data Exchange (ETDEWEB)

    Moat, R.J., E-mail: richard.moat@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom); Pinkerton, A.J.; Li, L. [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, M60 1QD (United Kingdom); Withers, P.J.; Preuss, M. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)

    2011-03-15

    Research highlights: {yields} Neutron diffraction and the contour method show good agreement. {yields} Tensile stresses found parallel to the surfaces. {yields} Compressive stresses within the bulk of the structures. {yields} Residual stress weakly dependent on the laser pulse parameters. {yields} Maximum tensile residual stress unaffected across range of pulse parameters used. - Abstract: This paper reports a study into the effect of laser pulse length and duty cycle on the residual stress distributions in multi-track laser direct metal deposits of Waspaloy onto an Inconel 718 substrate. The residual stresses have been evaluated using neutron diffraction and the contour method, while electron microscopy and micro hardness indentation have been used to map the concomitant microstructural variation. In all cases, near the tops of the deposited walls, the longitudinal stresses are tensile towards the mid-length of the wall, while the stresses perpendicular to the substrate are negligible. By contrast near the base of the walls, the stresses along the direction of deposition are small, while the stresses perpendicular to the substrate are compressive at the centre and tensile towards the ends. Consistent with previous observations, the stresses parallel to free surfaces are tensile, balanced by compressive stresses in the interior (an inverse quench stress profile). These profiles have been found to be weakly dependent on the laser pulse parameters, most notably an increase in tensile stress gradient with increasing duty cycle, but the maximum residual stresses are largely unaffected. Furthermore, microstructural analysis has shown that the effect of laser pulse parameters on grain morphology in multi-track thick walls is less marked than previously reported for single-track wall structures.

  5. Laser beam welding of Waspaloy: Characterization and corrosion behavior evaluation

    Science.gov (United States)

    Shoja Razavi, Reza

    2016-08-01

    In this work, a study on Nd:YAG laser welding of Waspaloy sheets has been made. Microstructures, phase changes and hardness of the laser joint were investigated using optical microscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD) and vickers microhardness (HV0.3). Corrosion behavior of the weldment at low temperature in 3.5%wt NaCl solution at room temperature was also investigated using open circuit potential and cyclic potentiodynamic polarization tests. Hot corrosion studies were conducted on samples in the molten salt environment (Na2SO4-60%V2O5) at 900 °C for 50 h. Results indicated that the microstructure of weld zone was mainly dendritic grown epitaxially in the direction perpendicular to the weld boundary and heat transfer. Moreover, the Ti-Mo carbide particles were observed in the structure of the weld zone and base metal. The average size of carbides formed in the base metal (2.97±0.5 μm) was larger than that of the weld zone (0.95±0.2 μm). XRD patterns of the weld zone and base metal showed that the laser welding did not alter the phase structure of the weld zone, being in γ-Ni(Cr) single phase. Microhardness profile showed that the hardness values of the weld zone (210-261 HV) were lower than that of the base metal (323-330 HV). Electrochemical and hot corrosion tests indicated that the corrosion resistance of the weld metal was greater than the base metal in both room and high temperatures.

  6. Stress relaxation behavior and mechanism of AEREX350 and Waspaloy superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuzhou; Dong, Jianxin; Zhang, Maicang; Yao, Zhihao

    2016-12-15

    The relaxation properties of AEREX350 and Waspaloy were studied contrastively at temperatures ranging from 600 °C to 800 °C with the same initial stress 510 MPa. The relationship between the microstructure and relaxation properties was elucidated using scanning and transmission electron microscopy techniques. It was found that the relaxation limit and relaxation stability of the two alloys decreased obviously with the increase of temperature, but the relaxation stability of AEREX350 decreased more slowly compared with Waspaloy. Further investigations show that the relaxation behavior is mainly depended on both precipitate characteristics and its interaction with dislocations. The complex precipitates evolution of AEREX350 alloy leads to a higher relaxation limit at high temperature 800 °C, but more quantity of γ′ in Waspaloy results in a higher relaxation limit at the low temperature of 600 °C. Thus it is suggested that as fastener alloys, Waspaloy is more suitable for low temperature service while AEREX350 is the preferred choice for high temperature service.

  7. LCF life prediction for waspaloy in the creep-fatigue interaction regime

    International Nuclear Information System (INIS)

    Yeom, Jong Taek; Park, Nho Kwang

    2001-01-01

    This paper describes the empirical rule of strain rate modified linear accumulation of creep damage(SRM rule) for Low-Cycle Fatigue(LCF) life prediction of Waspaloy in the creep-fatigue interaction regime and Chaboche type unified viscoplastic model predicting the stress-strain response in various cyclic loading conditions. The comparison of the experimental data and the predictions for strain controlled LCF tests carried out for various strain ranges at 600 .deg. C and 650 .deg. C was made. Chaboche type unified viscoplastic model described efficiently the inelastic deformation behavior during LCF tests. Crack-initiation lifting method to predict the material life was investigated with Strain Rate Modification(SRM) rule. The application of SRM rule to LCF tests on Waspaloy indicated a good agreement between measured and predicted cycles to failure

  8. “Investigations on the machinability of Waspaloy under dry environment”

    Science.gov (United States)

    Deepu, J.; Kuppan, P.; SBalan, A. S.; Oyyaravelu, R.

    2016-09-01

    Nickel based superalloy, Waspaloy is extensively used in gas turbine, aerospace and automobile industries because of their unique combination of properties like high strength at elevated temperatures, resistance to chemical degradation and excellent wear resistance in many hostile environments. It is considered as one of the difficult to machine superalloy due to excessive tool wear and poor surface finish. The present paper is an attempt for removing cutting fluids from turning process of Waspaloy and to make the processes environmentally safe. For this purpose, the effect of machining parameters such as cutting speed and feed rate on the cutting force, cutting temperature, surface finish and tool wear were investigated barrier. Consequently, the strength and tool wear resistance and tool life increased significantly. Response Surface Methodology (RSM) has been used for developing and analyzing a mathematical model which describes the relationship between machining parameters and output variables. Subsequently ANOVA was used to check the adequacy of the regression model as well as each machining variables. The optimal cutting parameters were determined based on multi-response optimizations by composite desirability approach in order to minimize cutting force, average surface roughness and maximum flank wear. The results obtained from the experiments shown that machining of Waspaloy using coated carbide tool with special ranges of parameters, cutting fluid could be completely removed from machining process

  9. Length change of the alloys Waspaloy and Inconel 718 after long-term annealing; Laengenaenderung der Legierungen Waspaloy und Inconel 718 nach Langzeitauslagerung

    Energy Technology Data Exchange (ETDEWEB)

    Kinzel, Svenja

    2016-07-01

    Within the scope of this work the contraction behavior of Ni-based superalloy Waspaloy could in detail be referred to a combination of different microstructural changes and the results could partially be transferred to Ni-Fe-based alloy Inconel 718. Isothermal annealing of sample rods at temperatures between 450 C and 750 C induces an average relative length contraction of about -2.10{sup -4}. It is apparent that contraction is more pronounced for lower temperatures (-3.10{sup -4} at 550 C) than for higher ones (-1.10{sup -4} at 750 C). Within the first 300 hours of annealing the contraction reaches about 70-75% of the value measured after 10,000 hours. This means the major part of the effect takes place at the beginning of long term annealing but even after 10,000 hours no saturation occurs. On the basis of lattice parameter measurements it could be found that within the first 300 hours a significant lattice parameter decrease of matrix and γ{sup '} phase emerged. Longer annealing time does not cause further lattice contraction. This sample behavior can be explained by temperature dependence of phase fractions and phase compositions. Thermodynamic calculations as well as stereological analysis of micrographs show a decrease of stable γ{sup '}-phase content with increasing temperature. In parallel, TEM-EDS measurements and calculated phase fractions show concentration fluctuations due to the different precipitate fraction, which cause contraction of the lattice parameter. Furthermore, within the first 100 hours at temperatures up to 650 C the formation or Ni-Cr rich domains could be observed. As these domains exhibit a smaller lattice parameter than the matrix they contribute to the more pronounced contraction at lower temperatures. While XRD measurements point to the formation of Ni{sub 3}Cr, TEM-EDS measurements reveal a composition of (Ni,Co){sub 2}Cr. Stress relief heat treatment at higher temperatures (815 C) after annealing shows that the effect

  10. Length change of the alloys Waspaloy and Inconel 718 after long-term annealing

    International Nuclear Information System (INIS)

    Kinzel, Svenja

    2016-01-01

    Within the scope of this work the contraction behavior of Ni-based superalloy Waspaloy could in detail be referred to a combination of different microstructural changes and the results could partially be transferred to Ni-Fe-based alloy Inconel 718. Isothermal annealing of sample rods at temperatures between 450 C and 750 C induces an average relative length contraction of about -2.10"-"4. It is apparent that contraction is more pronounced for lower temperatures (-3.10"-"4 at 550 C) than for higher ones (-1.10"-"4 at 750 C). Within the first 300 hours of annealing the contraction reaches about 70-75% of the value measured after 10,000 hours. This means the major part of the effect takes place at the beginning of long term annealing but even after 10,000 hours no saturation occurs. On the basis of lattice parameter measurements it could be found that within the first 300 hours a significant lattice parameter decrease of matrix and γ"' phase emerged. Longer annealing time does not cause further lattice contraction. This sample behavior can be explained by temperature dependence of phase fractions and phase compositions. Thermodynamic calculations as well as stereological analysis of micrographs show a decrease of stable γ"'-phase content with increasing temperature. In parallel, TEM-EDS measurements and calculated phase fractions show concentration fluctuations due to the different precipitate fraction, which cause contraction of the lattice parameter. Furthermore, within the first 100 hours at temperatures up to 650 C the formation or Ni-Cr rich domains could be observed. As these domains exhibit a smaller lattice parameter than the matrix they contribute to the more pronounced contraction at lower temperatures. While XRD measurements point to the formation of Ni_3Cr, TEM-EDS measurements reveal a composition of (Ni,Co)_2Cr. Stress relief heat treatment at higher temperatures (815 C) after annealing shows that the effect of contraction is reversible. It causes an

  11. Using internally cooled cutting tools in the machining of difficult-to-cut materials based on Waspaloy

    Directory of Open Access Journals (Sweden)

    Yahya Isik

    2016-05-01

    Full Text Available Nickel-based superalloys such as Waspaloy are used for engine components and in the nuclear industry, where considerable strength and corrosion resistance at high operating temperatures are called for. These characteristics of such alloys cause increases in cutting temperature and resultant tool damage, even at low cutting speeds and low feed rates. Thus, they are classified as difficult-to-cut materials. This article presents a cooling method to be used in metal cutting based on a tool holder with a closed internal cooling system with cooling fluid circulating inside. Hence, a green cooling method that does not harm the environment and is efficient in removing heat from the cutting zone was developed. A series of cutting experiments were conducted to investigate the practicality and effectiveness of the internally cooled tool model. The developed system achieved up to 13% better surface quality than with dry machining, and tool life was extended by 12%. The results clearly showed that with the reduced cutting temperature of the internal cooling, it was possible to control the temperature and thus prevent reaching the critical cutting temperature during the turning process, which is vitally important in extending tool life during the processing of Waspaloy.

  12. Etch pit and γ' precipitate evolution in controlled Waspaloy microstructures aged at 725, 800 and 875 deg. C

    International Nuclear Information System (INIS)

    Kelekanjeri, V. Siva Kumar G.; Gerhardt, Rosario A.

    2009-01-01

    In this paper, controlled microstructures of Waspaloy were produced with the objective of studying the kinetic mechanisms that drive microstructural evolution during short-term aging. Three individual sets of controlled microstructures were produced by an initial solution-treatment at 1145 deg. C followed by aging-treatments at 725, 800 and 875 deg. C for times up to 263.5 h. The resulting microstructures varied markedly from one aging set to the next. The three sets of aged specimens were systematically characterized via microscopy (SEM and AFM), DC four-point probe resistivity and X-ray diffraction techniques. The occurrence of perfect polygonal etch-pit shapes in the solution-treated microstructures, which transformed upon aging first into corner-rounded shapes, followed by irregular shapes and eventual dissolution, was evidenced here. This phenomenon of transformation of etch-pit shapes appears to occur concurrently with gamma prime nucleation and growth. The formation mechanism of the etch-pits and subsequent microstructural evolution upon aging are discussed herein

  13. Characterization of microstructural fluctuations in Waspaloy exposed to 760 deg. C for times up to 2500 h

    International Nuclear Information System (INIS)

    Kelekanjeri, V. Siva Kumar G.; Gerhardt, Rosario A.

    2006-01-01

    The microstructure of Waspaloy, a nickel-base superalloy, was investigated as a function of thermal exposure to 760 deg. C for times up to 2502 h. The primary strengthening phase in this material is the γ' precipitate phase-Ni 3 (Al, Ti). The microstructure of the specimens was monitored using impedance spectroscopy (IS), X-ray diffraction (XRD), optical and scanning electron microscopy (SEM). The average grain size varied significantly during thermal exposure. SEM analysis indicated that the precipitates had a bimodal size distribution, with morphologies ranging from spherical to cubic. High-resolution XRD experiments indicated that the γ' lattice parameter is a non-linear function of the exposure time. Energy dispersive (EDS) analysis of Al and Ti composition in the matrix surrounding the primary γ' precipitates also varied. The normalized admittance maximum displayed a partial inverse correlation with the volume fraction of the primary γ' precipitates, and a partial direct correlation with the matrix grain size as a function of thermal exposure time. It is hypothesized that the fluctuations detected by the above techniques are indicative of repetitive nucleation, coarsening and dissolution events occurring during the course of the extended thermal exposure. These results suggest that IS may be useful for monitoring the microstructure of these alloys non-destructively

  14. Variation in diffusion-induced solidification rate of liquated Ni-Cr-B insert during TLP bonding of Waspaloy superalloy

    International Nuclear Information System (INIS)

    Tokoro, K.; Wikstrom, N.P.; Ojo, O.A.; Chaturvedi, M.C.

    2008-01-01

    A microstructural study was performed on transient liquid phase (TLP) bonded Waspaloy superalloy with a Ni-Cr-B filler. The applicability of a diffusion model based on Fick's second law of diffusion to determine the time required for complete isothermal solidification (t f ) was investigated. Over the temperature range of 1065-1110 deg. C, experimental observations of t f were in reasonable agreement with t f values predicted by the diffusion model. However, a notable deviation was observed in joints prepared between 1175 and 1225 deg. C in that the rate of isothermal solidification was reduced at these temperatures resulting in the formation of a centerline eutectic-type microconstituent, which in contrast, was prevented from forming after holding the brazing assembly for an equivalent bonding time at a lower temperature of 1145 deg. C. Boride particles were observed as part of the eutectic product, which suggested that diffusion of boron out of the liquated insert was also reduced at these higher temperatures. A decrease in solubility of the melting point depressing solute, boron, with increase in temperature is suggested to be an important factor contributing to the reduction in isothermal solidification rate observed at the higher bonding temperatures

  15. SANS investigation of precipitate microstructure in nickel-base superalloys Waspaloy and DT750

    Czech Academy of Sciences Publication Activity Database

    Strunz, Pavel; Zrník, J.; Seliga, T.; Penkalla, H.J.

    2006-01-01

    Roč. 2, č. 23 (2006), s. 363-368 ISSN 0044-2968 R&D Projects: GA ČR GA202/06/0601 Institutional research plan: CEZ:AV0Z10480505 Keywords : small-angle-neutron scattering * superalloys * precipitation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.897, year: 2006

  16. Fatigue and creep cracking of nickel alloys for 700 C steam turbines

    International Nuclear Information System (INIS)

    Berger, C.; Granacher, J.; Thoma, A.; Roesler, J.; Del Genovese, D.

    2001-01-01

    Four materials of the types Inconel 706 (two heat treatment states), Inconel 617, and Waspaloy were tested as shaft materials for 700 to 720 C steam turbines. At an extrapolation time ratio of 10, Waspaloy was expected to have the highest creep strength (about 270 MPa at 700 C), with values of about 140 MPa at 700 C for Inconel 617. A preliminary evaluation of the 700 C creep rupture tests showed the highest creep rupture resistance for Inconel 617, followed by Waspaloy and Inconel 706 [de

  17. Life Prediction Methodologies for Aerospace Materials

    National Research Council Canada - National Science Library

    Ashbaugh, N. E; Brockman, R. A; Buchanan, D. J; Hartman, G. A; Huston, A. L; Li, K; Porter, W. J

    2004-01-01

    Superalloys IN-100, Ren 88DT, Waspaloy, and titanium alloys were investigated. For life-limiting responses in superalloys, highly localized stress-deformation behaviors associated with both typical and unusual defects were developed...

  18. Analysis and Elimination of High Temperature Notch Induced Microcrack Initiation in Inconel 718 Nickel-Based Alloy

    Science.gov (United States)

    1989-01-01

    Compressor Rear Frame (ClF) which exhibits extensive cract:ing of the forward flange. ThL 1988 Actuarial Function data shows CRF crackiing As the number 2...Creep-Rupture properties of Waspaloy sheet to Sharp-Edged Notches in the Temperature Range of 1O000F-14O0OF. Journal of Basle Engineering, Trans ASME ...Dependence of the Notch Sensitivity of Waspaloy at 10000F-1400F on the Gamma Prime Phase, Journal of Basic Engineering, Trans ASME (in print at time of

  19. Laser Engineered Net Shape (LENS) Technology for the Repair of Ni-Base Superalloy Turbine Components

    Science.gov (United States)

    Liu, Dejian; Lippold, John C.; Li, Jia; Rohklin, Stan R.; Vollbrecht, Justin; Grylls, Richard

    2014-09-01

    The capability of the laser engineered net shape (LENS) process was evaluated for the repair of casting defects and improperly machined holes in gas turbine engine components. Various repair geometries, including indentations, grooves, and through-holes, were used to simulate the actual repair of casting defects and holes in two materials: Alloy 718 and Waspaloy. The influence of LENS parameters, including laser energy density, laser scanning speed, and deposition pattern, on the repair of these defects and holes was studied. Laser surface remelting of the substrate prior to repair was used to remove machining defects and prevent heat-affected zone (HAZ) liquation cracking. Ultrasonic nondestructive evaluation techniques were used as a possible approach for detecting lack-of-fusion in repairs. Overall, Alloy 718 exhibited excellent repair weldability, with essentially no defects except for some minor porosity in repairs representative of deep through-holes and simulated large area casting defects. In contrast, cracking was initially observed during simulated repair of Waspaloy. Both solidification cracking and HAZ liquation cracking were observed in the repairs, especially under conditions of high heat input (high laser power and/or low scanning speed). For Waspaloy, the degree of cracking was significantly reduced and, in most cases, completely eliminated by the combination of low laser energy density and relatively high laser scanning speeds. It was found that through-hole repairs of Waspaloy made using a fine powder size exhibited excellent repair weldability and were crack-free relative to repairs using coarser powder. Simulated deep (7.4 mm) blind-hole repairs, representative of an actual Waspaloy combustor case, were successfully produced by the combination use of fine powder and relatively high laser scanning speeds.

  20. Strength and structure during hot deformation of nickel-base superalloys

    International Nuclear Information System (INIS)

    Ribeiro, N.D.; Sellars, C.M.

    1984-01-01

    The effect of deformational variables on the flow stress and microstructure developed by plane strain compression testing and experimental rolling of three otherwise well characterized nickel-base super alloys, Nimonic 80A, Nimonic 90 and Waspaloy are presented. Rolled or tested samples were sectioned longitudinally at mid-width and were prepared for optical metallography. X-ray analysis of particles observed in several samples was carried out on polished and lightly etehed surfaces using a diffractometer with CoKα radiation. For other samples, energy dispersive x-ray analysis was also carried out in a scanning microscope. (E.G.) [pt

  1. Investigations of the microstructural stability of wrought Ni-(Fe)-based syperalloys for steam turbine rotor application beyond 700 C; Untersuchungen der Strukturstabilitaet von Ni-(Fe)-Basislegierungen fuer Rotorwellen in Dampfturbinen mit Arbeitstemperaturen ueber 700 C

    Energy Technology Data Exchange (ETDEWEB)

    Seliga, T.

    2005-07-01

    There is a continuous trend to improve the efficiency of modern power plants with steam turbine require operating steam temperature from 700 to 720 C. For substantial parts like turbine rotors and discs this means increased requirements on the high temperature resistance, which can not longer be fulfilled by the presently used steel. As new materials for the components, which are thermo-mechanically loaded, only Ni-based superalloys are suitable for their fabrication, structure stability and thermo-mechanical characteristics. With view on creep and creep crack growth resistance as suitable candidates in the context a DFG research project wrought Ni-based superalloy Waspaloy and Ni-Fe-based alloy Inconel 706 were selected, which exhibited different hardening mechanisms. Waspaloy is a {gamma}'-hardened material with small portion of carbides on the grain boundaries. Inconel 706 is a particle hardened alloy with a very complex microstructure, it consists of {gamma}', {gamma}{sup ''}-particle, {eta}-phase und carbides. Concerning to their castability, forgeability, creep and creep crack growth and microstructural stability these candidate materials have been investigated and modelled. The knowledge about their long time stability of the microstructure, castability, forgeability and mechanical properties leads to the two new modification (Waspaloy{yields}DT750 and Inconel 706{yields}DT706). The modification of the Waspaloy to DT 750 served better castability (elimination of the Freckle formation). An improvement of the long-term stability of the microstructure was not necessary, by a changed heat treatment was reached a homogeneous, monomodale {gamma}'-particle distribution. The modification of Inconel 706 to DT 706 served to stabilize the {gamma}'-phase and to reduce of the {gamma}{sup ''} phase without suppressing the cellular {eta}-phase colonies on the grain boundaries. This work presents the test results for the structural

  2. Determination of emissivity coefficient of heat-resistant super alloys and cemented carbide

    Directory of Open Access Journals (Sweden)

    Kieruj Piotr

    2016-12-01

    Full Text Available This paper presents the analysis of emissivity engineering materials according to temperature. Experiment is concerned on difficult to machine materials, which may be turned with laser assisting. Cylindrical samples made of nickel-based alloys Inconel 625, Inconel 718, Waspaloy and tungsten-carbides based on cobalt matrix were analyzed. The samples’ temperature in contact method was compared to the temperature measured by non-contact pyrometers. Based on this relative, the value of the emissivity coefficient was adjusted to the right indication of pyrometers.

  3. Creep-fatigue interaction at high temperature; Proceedings of the Symposium, 112th ASME Winter Annual Meeting, Atlanta, GA, Dec. 1-6, 1991

    Science.gov (United States)

    Haritos, George K.; Ochoa, O. O.

    Various papers on creep-fatigue interaction at high temperature are presented. Individual topics addressed include: analysis of elevated temperature fatigue crack growth mechanisms in Alloy 718, physically based microcrack propagation laws for creep-fatigue-environment interaction, in situ SEM observation of short fatigue crack growth in Waspaloy at 700 C under cyclic and dwell conditions, evolution of creep-fatigue life prediction models, TMF design considerations in turbine airfoils of advanced turbine engines. Also discussed are: high temperature fatigue life prediction computer code based on the total strain version of strainrange partitioning, atomic theory of thermodynamics of internal variables, geometrically nonlinear analysis of interlaminar stresses in unsymmetrically laminated plates subjected to uniform thermal loading, experimental investigation of creep crack tip deformation using moire interferometry. (For individual items see A93-31336 to A93-31344)

  4. New vistas in the determination of hydrogen in aerospace engine metal alloys

    Science.gov (United States)

    Danford, M. D.

    1986-01-01

    The application of diffusion theory to the analysis of hydrogen desorption data has been studied. From these analyses, important information concerning hydrogen solubilities and the nature of the hydrogen distributions in the metal has been obtained. Two nickel base alloys, Rene' 41 and Waspaloy, and one ferrous alloy, 4340 steel, were studied in this work. For the nickel base alloys, it was found that the hydrogen distributions after electrolytic charging conformed closely to those which would be predicted by diffusion theory. The hydrogen distributions in electrolytically charged 4340 steel, on the other hand, were essentially uniform in nature, which would not be predicted by diffusion theory. Finally, it has been found that the hydrogen desorption is completely explained by the nature of the hydrogen distribution in the metal, and that the 'fast' hydrogen is not due to surface and subsurface hydride formation, as was originally proposed.

  5. The effect of heat treatment on the micro-structure and the mechanical properties of high-temperature nickel-base-superalloys

    International Nuclear Information System (INIS)

    Schubert, R.; Horn, E.

    1974-01-01

    General review of heat treatment applied to high-temperature nickel-base-superalloys as a function of the volume percent of the γ'-phase. Heat treatment schedule. γ'-morphology and γ'-distribution as well as their effect on mechanical properties. Values obtained from tensile tests up to 1,000 0 C. Results obtained from creep tests. Limitation for the heat treatment of alloys having an unstable γ'-phase. Alloys X 5 NiCrTi 26 15, ATS 270 (approximately INCO 718), NiCr 20 TiAl, NiCr 20 Co 18 Ti, ATS 342 (approximately Waspaloy), ATS 354 (approximately Udimet 520), NiCo 20 Cr 15 MoAlTi, ATS 382 (approximately Udimet 710), ATS 381-G (approximately Mar M 246), FIS 145 and ATS 391-G (aproximately IN 100). (orig.) [de

  6. An investigation of the effect of load ratio on near-threshold fatigue crack propagation in a Ni-Base superalloy

    International Nuclear Information System (INIS)

    Schooling, J.M.; Reed, P.A.S.

    1995-01-01

    The near-threshold fatigue crack growth behavior of Waspaloy has been investigated to elucidate important parameters relevant to the development of a modelling program for fatigue behavior in Ni-base superalloys. At low values of load-ratio, R, threshold stress intensity values are found to be highly sensitive to R. This behavior is rationalized in terms of roughness induced crack closure. At high load ratios there is less sensitivity to R, and stage II behavior appears to persist to threshold. The threshold stress intensity at high R-ratios is lower than that for closure corrected Stage I (low load ratio) threshold behavior, indicating the existence of two intrinsic threshold values. This difference appears to be due not only to crack branching and deflection in Stage I, but also to be intrinsic difference in resistance to threshold behavior in the two growth modes. (author)

  7. Cylindrical plunge grinding of difficult to grind materials

    International Nuclear Information System (INIS)

    Nakajima, Toshikatsu; Uno, Yoshiyuki; Kayahara, Masayuki.

    1983-01-01

    Cylindrical plunge grinding processes of titanium alloy and nickel-base superalloys with various kinds of conventional grinding wheels, which are known as difficult to grind materials, are experimentally investigated, analyzing size generation process, grinding force, surface roughness, wheel wear, grinding ratio and so on. For grinding titanium alloy Ti-6Al-4V, GC grinding wheel yields most superior grinding results which leads to lower grinding force, smaller residual stock, less wheel wear and higher grinding ratio up to about 3 with GC 80 L 9 V wheel. Then, for grinding nickelbase superalloys Waspaloy and Rene 41, WA 150 L 9 V wheel yields better grinding results in surface roughness, wheel wear, grinding ratio without chatter vibration though grinding force is higher, and the grinding ratio about 3 is obtained. Furthermore, higher plunge speed and speed ratio result in higher grinding efficiency though grinding force, surface roughness, wheel wear increase for grinding titanium alloy and nickel-base superalloys. (author)

  8. Wear and Reactivity Studies of Melt infiltrated Ceramic Matrix Composite

    Science.gov (United States)

    Jarmon, David C.; Ojard, Greg; Brewer, David N.

    2013-01-01

    As interest grows in the use of ceramic matrix composites (CMCs) for critical gas turbine engine components, the effects of the CMCs interaction with the adjoining structure needs to be understood. A series of CMC/material couples were wear tested in a custom elevated temperature test rig and tested as diffusion couples, to identify interactions. Specifically, melt infiltrated silicon carbide/silicon carbide (MI SiC/SiC) CMC was tested in combination with a nickel-based super alloy, Waspaloy, a thermal barrier coating, Yttria Stabilized Zirconia (YSZ), and a monolithic ceramic, silicon nitride (Si3N4). To make the tests more representative of actual hardware, the surface of the CMC was kept in the as-received state (not machined) with the full surface features/roughness present. Test results include: scanning electron microscope characterization of the surfaces, micro-structural characterization, and microprobe analysis.

  9. Finite element modelling of shot peening process: Prediction of the compressive residual stresses, the plastic deformations and the surface integrity

    International Nuclear Information System (INIS)

    Frija, M.; Hassine, T.; Fathallah, R.; Bouraoui, C.; Dogui, A.

    2006-01-01

    This paper presents a numerical simulation of the shot peening process using finite element method. The majority of the controlling parameters of the process have been taken into account. The shot peening loading has been characterised by using energy equivalence between the dynamic impact and a static indentation of a peening shot in the treated surface. The behaviour of the subjected material is supposed to be elastic plastic with damage. An integrated law of the damage proposed by Lemaitre and Chaboche has been used. The proposed model leads to obtain the residual stress, the plastic deformation profiles and the surface damage. An application on a shot peened Ni-based super alloy Waspaloy has been carried out. The comparison of the residual stresses, obtained by X-ray diffraction method and by finite element calculation, shows a good correlation. The in-depth profile of the plastic deformations and the superficial damage values are in good agreement with the experimental observations

  10. On the Feasibility of Eddy Current Characterization of the Near-Surface Residual Stress Distribution in Nickel-Base Superalloys

    International Nuclear Information System (INIS)

    Blodgett, Mark P.; Nagy, Peter B.

    2004-01-01

    In light of its frequency-dependent penetration depth, the measurement of eddy current conductivity has been suggested as a possible means to allow the nondestructive evaluation of subsurface residual stresses in shot-peened specimens. This technique is based on the so-called electroelastic effect, i.e., the stress-dependence of the electrical conductivity. Unfortunately, the relatively small (∼1%) change in electrical conductivity caused by the presence of compressive residual stresses is often distorted, or even completely overshadowed, by the accompanying conductivity loss caused by cold work and surface roughness effects. Recently, it was observed that, in contrast with most other materials, shot-peened Waspaloy and IN100 specimens exhibit an apparent increase in electrical conductivity at increasing inspection frequencies. This observation by itself indicates that in these materials the measured conductivity change is probably dominated by residual stress effects, since both surface roughness and increased dislocation density are known to decrease rather than increase the conductivity and the presence of crystallographic texture does not affect the electrical conductivity of these materials, which crystallize in cubic symmetry. Our preliminary experiments indicate that probably there exists a unique 'window of opportunity' for eddy current NDE in nickel-base superalloys. We identified five major effects that contribute to this fortunate constellation of material properties, which will be reviewed in this presentation

  11. Modification of creep and low cycle fatigue behaviour induced by welding

    Directory of Open Access Journals (Sweden)

    A. Carofalo

    2014-10-01

    Full Text Available In this work, the mechanical properties of Waspaloy superalloy have been evaluated in case of welded repaired material and compared to base material. Test program considered flat specimens on base and TIG welded material subjected to static, low-cycle fatigue and creep test at different temperatures. Results of uniaxial tensile tests showed that the presence of welded material in the gage length specimen does not have a relevant influence on yield strength and UTS. However, elongation at failure of TIG material was reduced with respect to the base material. Moreover, low-cycle fatigue properties have been determined carrying out tests at different temperature (room temperature RT and 538°C in both base and TIG welded material. Welded material showed an increase of the data scatter and lower fatigue strength, which was anyway not excessive in comparison with base material. During test, all the hysteresis cycles were recorded in order to evaluate the trend of elastic modulus and hysteresis area against the number of cycles. A clear correlation between hysteresis and fatigue life was found. Finally, creep test carried out on a limited number of specimens allowed establishing some changes about the creep rate and time to failure of base and welded material. TIG welded specimen showed a lower time to reach a fixed strain or failure when a low stress level is applied. In all cases, creep behaviour of welded material is characterized by the absence of the tertiary creep.

  12. High temperature diffusion induced liquid phase joining of a heat resistant alloy

    International Nuclear Information System (INIS)

    Wikstrom, N.P.; Egbewande, A.T.; Ojo, O.A.

    2008-01-01

    Transient liquid phase bonding (TLP) of a nickel base superalloy, Waspaloy, was performed to study the influence of holding time and temperature on the joint microstructure. Insufficient holding time for complete isothermal solidification of liquated insert caused formation of eutectic-type microconstituent along the joint centerline region in the alloy. In agreement with prediction by conventional TLP diffusion models, an increase in bonding temperature for a constant gap size, resulted in decrease in the time, t f, required to form a eutectic-free joint by complete isothermal solidification. However, a significant deviation from these models was observed in specimens bonded at and above 1175 deg. C. A reduction in isothermal solidification rate with increased temperature was observed in these specimens, such that a eutectic-free joint could not be achieved by holding for a time period that produced complete isothermal solidification at lower temperatures. Boron-rich particles were observed within the eutectic that formed in the joints prepared at the higher temperatures. An overriding effect of decrease in boron solubility relative to increase in its diffusivity with increase in temperature, is a plausible important factor responsible for the reduction in isothermal solidification rate at the higher bonding temperatures

  13. Assessment of dynamic softening mechanisms in Allvac 718Plus{sup TM} by EBSD analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mitsche, Stefan, E-mail: stefan.mitsche@felmi-zfe.at [Institute for Electron Microscopy, Graz University of Technology, Steyrergasse 17, Graz (Austria); Sommitsch, Christof [Institute for Material Science and Welding, Christian Doppler Laboratory for Materials Modelling and Simulation, Graz University of Technology, Graz (Austria); Huber, Daniel; Stockinger, Martin [Boehler Schmiedetechnik GmbH and Co KG, Kapfenberg (Austria); Poelt, Peter [Institute for Electron Microscopy, Graz University of Technology, Steyrergasse 17, Graz (Austria)

    2011-04-25

    Research highlights: {yields} EBSD investigations of hot deformed superalloy Allvac 718Plus{sup TM}. {yields} Dynamic softening (recovery, DDRX and CDRX) in dependence on the temperature and strain rate. {yields} At high temperature (1050 deg. C) and high strain rate (10 s{sup -1}) mainly DDRX. {yields} At high temperature (1050 deg. C) and low strain rate (0.1 s{sup -1}) combination of DDRX, CDRX and recovery. - Abstract: The nickel-based superalloy Allvac 718Plus{sup TM} is a future candidate for turbine disc applications, as this new material combines the formability and cost advantages of Alloy 718 with the higher temperature capability of Waspaloy. Due to the strong influence of the microstructure on the final mechanical properties, a fundamental knowledge of the dynamic recrystallization mechanism of Allvac 718Plus{sup TM} is of great importance in order to develop precise microstructure evolution models for this material. Compression tests were performed at temperatures of 900 deg. C to 1050 deg. C and strain rates between 0.1 s{sup -1} and 10 s{sup -1}. The microstructures obtained were analyzed by electron backscatter diffraction (EBSD) to evaluate the influence of the different hot forming parameters on the dynamic softening processes of Allvac 718Plus{sup TM}.

  14. Thermo-Viscoplastic Behavior of Ni-Based Superalloy Haynes 282 and Its Application to Machining Simulation

    Directory of Open Access Journals (Sweden)

    Marcos Rodríguez-Millán

    2017-12-01

    Full Text Available Ni-based superalloys are extensively used in high-responsibility applications in components of aerospace engines and gas turbines with high temperature service lives. The wrought, γ’-strengthened superalloy Haynes 282 has been recently developed for applications similar to other common superalloys, such as Waspaloy or Inconel 718, with improved creep behavior, thermal stability, and fabrication ability. Despite the potential of Haynes 282, there are still important gaps in the knowledge of the mechanical behavior of this alloy. In fact, it was not possible to find information concerning the mechanical behavior of the alloy under impulsive loading. This paper focuses on the mechanical characterization of the Haynes 282 at strain rates ranging from 0.1 to 2800 s−1 and high temperatures ranging from 293 to 523 K using Hopkinson bar compression tests. The experimental results from the thermo-mechanical characterization allowed for calibration of the Johnson–Cook model widely used in modeling metallic alloy’s responses under dynamic loading. Moreover, the behavior of Haynes 282 was compared to that reported for Inconel 718, and the results were used to successfully model the orthogonal cutting of Haynes 282, being a typical case of dynamic loading requiring previous characterization of the alloy.

  15. Experimental and petrological constraints on long-term magma dynamics and post-climactic eruptions at the Cerro Galán caldera system, NW Argentina

    Science.gov (United States)

    Grocke, Stephanie B.; Andrews, Benjamin J.; de Silva, Shanaka L.

    2017-11-01

    Cerro Galán in NW Argentina records > 3.5 Myr of magmatic evolution of a major resurgent caldera complex. Beginning at 5.72 Ma, nine rhyodacitic ignimbrites (68-71 wt% SiO2) with a combined minimum volume of > 1200 km3 (Dense Rock Equivalent; DRE) have been erupted. The youngest of those ignimbrites is the eponymous, geochemically homogenous, caldera-forming 2.08 ± 0.02 Ma Cerro Galán Ignimbrite (CGI; > 630 km3 DRE). Following this climactic supereruption, structural and magmatic resurgence led to the formation of a resurgent dome and post-climactic lava domes and their associated pyroclastic deposits. A clear transition from amphibole to sanidine-bearing magmas occurred during the evolution of Cerro Galán and is inferred to represent a shallowing of the magma system. We test this hypothesis here using experimental phase equilibria. We conducted a series of phase equilibria experiments on the post-climactic dome lithologies under H2O-saturated conditions using cold seal Waspaloy pressure vessels with an intrinsic log fO2 of NNO + 1 ± 0.5 across a temperature-pressure range of 750-900 °C and 50-200 MPa (PH2O = Ptotal), respectively. Petrologic and geochemical analysis of the post-climactic lithologies shows that the natural phase assemblage (plagioclase + quartz + biotite + sanidine + Fe-Ti oxides ± apatite ± zircon) is stable at history of Cerro Galán is informed through a detailed investigation of the textural differences among the post-climactic dome lithologies, and a comparison of those textures with previously published decompression experiments. These suggest that the highly vesiculated, pumiceous clasts with rare microlites represent magma stored within the core of the lava dome that decompressed relatively rapidly (0.003-0.0003 MPa s-1) and evolved via closed system degassing. Resulting over-pressure of the dome may have triggered superficial explosion. In contrast, dense clasts with abundant crystalline silica precipitates represent more typical