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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Microstructural Characteristics, Mechanical Properties, and Corrosion Behavior of Field-Assisted Diffusion Welded Alloy 617

This study investigated the microstructural characteristics, mechanical response, and corrosion resistance of Alloy 617 diffusion welded by electric field-assisted sintering (EFAS). The microstructure exhibited good grain boundary (GB) migration across the interface and flat interface in the samples bonded at different conditions. Graded grain size was observed, with grain coarsening being more significant near sample surface due to EFAS-induced temperature gradient. Tensile testing revealed that the specimens fractured in the matrix away from the interface. The peak strength of 807 MPa was obtained in the samples welded at 1000°C. The materials obtained at 1100°C exhibited reduced tensile strength but improved ductility. Strain maps revealed by digital image correlation showed the flat interfaces were less ductile compared to the matrix. The hardness reduced near sample surfaces due to enlarged grains induced by temperature gradient. The interfaces with GB migration exhibited improved corrosion resistance in molten salt compared to the flat interfaces.

36 - MATERIALS SCIENCE↗
DOE OSTI2020

Wear Performance of incoloy 800HT and inconel 617 in various surface conditions for high-temperature gas-cooled reactor components

Incoloy™ 800HT and Inconel™ 617 are primary candidate structural materials for high-temperature gas-cooled reactors (HTGRs). Impurities (e.g., H 2 O, CH 4 ) in the coolant induce corrosion reactions that affect tribological behavior. We investigate the high-temperature tribological performance of the alloys under surface conditions including: conditioned in H 2 O-containing helium at elevated temperatures, hardened via the carbon-diffusion Kolsterising® treatment, and conditioned after hardening. Initial friction coefficients and volume removed serve as metrics for wear performance. In this work, we find that wear mechanisms including scuffing, glaze-oxide formation, and oxide-layer wear and break-through are governed by surface hardness, chemistry, and applied load. The formation of a glaze-oxide layer is achieved with an oxide of sufficient mechanical integrity if the oxide-substrate interface is strong and the load is low.

42 ENGINEERING↗
DOE OSTI2022

Nanomechanical and tribological properties of nickel–chromium multilayer coating on Inconel 617

Multilayer coatings of Ni and Cr were deposited onto Inconel 617, and multi-scale physical properties were characterized using high temperature tribological experiments, nanoindentation, and microscratch. The effect of high temperature aging (950 °C under helium environment) on two different Ni/Cr multilayer coatings with individual layer thicknesses of 50 and 200 nm denoted by Ni/Cr(50) and Ni/Cr(200) was investigated. Nanoindentation of original coatings showed a hardness of 6 GPa that increases to 14 GPa for both samples once aged. Microscratch results support the macro-tribology results where Ni/Cr(50) (without aging) was the only delaminated coating with significant wear. Additionally, aging in both cases reduced the in situ coefficient of friction and wear. Cross-section energy dispersive spectrometry confirmed that the aged oxide layer was two to three times thicker than the original coating. In conclusion, an abundance of chromium oxide was found in the main body of the coatings, which led to higher hardness and better wear resistance.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Internal Pressurization on the Creep-Fatigue Performance of Alloy 617 Based on Simplified Model Test Method

The Simplified Model Test (SMT) is an alternative approach to determine cyclic life at elevated temperature and avoids parsing the damage into creep and fatigue components. The original SMT concept [1] considered that the effects of sustained primary stress loading could be safely neglected because the allowable local stress and strain levels were much higher than the allowable sustained primary stress levels. This key assumption is critically evaluated on Alloy 617 using internal pressurized cylindrical SMT specimens at 950 °C. The impact of combined internal pressurization and displacement-controlled creep-fatigue loading on the SMT cycle life is demonstrated at different strain ranges. The effect of primary load on the SMT design method is discussed.

Wang, Yanli↗
DOE OSTI2015

Progress Report on Alloy 617 Time Dependent Allowables

Time dependent allowable stresses are required in the ASME Boiler and Pressure Vessel Code for design of components in the temperature range where time dependent deformation (i.e., creep) is expected to become significant. There are time dependent allowable stresses in Section IID of the Code for use in the non-nuclear construction codes, however, there are additional criteria that must be considered in developing time dependent allowables for nuclear components. These criteria are specified in Section III NH. St is defined as the lesser of three quantities: 100% of the average stress required to obtain a total (elastic, plastic, primary and secondary creep) strain of 1%; 67% of the minimum stress to cause rupture; and 80% of the minimum stress to cause the initiation of tertiary creep. The values are reported for a range of temperatures and for time increments up to 100,000 hours. These values are determined from uniaxial creep tests, which involve the elevated temperature application of a constant load which is relatively small, resulting in deformation over a long time period prior to rupture. The stress which is the minimum resulting from these criteria is the time dependent allowable stress St. In this report data from a large number of creep and creep-rupture tests on Alloy 617 are analyzed using the ASME Section III NH criteria. Data which are used in the analysis are from the ongoing DOE sponsored high temperature materials program, form Korea Atomic Energy Institute through the Generation IV VHTR Materials Program and historical data from previous HTR research and vendor data generated in developing the alloy. It is found that the tertiary creep criterion determines St at highest temperatures, while the stress to cause 1% total strain controls at low temperatures. The ASME Section III Working Group on Allowable Stress Criteria has recommended that the uncertainties associated with determining the onset of tertiary creep and the lack of significant cavitation associated with early tertiary creep strain suggest that the tertiary creep criteria is not appropriate for this material. If the tertiary creep criterion is dropped from consideration, the stress to rupture criteria determines St at all but the lowest temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Draft ASME Boiler and Pressure Vessel Code Section III, Division 5, Section HB, Subsection B, Code Case for Alloy 617 and Background Documentation

Alloy 617 is the leading candidate material for an intermediate heat exchanger for the very high temperature reactor. To evaluate the behavior of this material in the expected service conditions, strain controlled cyclic tests that include long hold times up to 240 minutes at maximum tensile strain were conducted at 850°C. In terms of the total number of cycles to failure, the fatigue resistance decreased when a hold time was added at peak tensile strain. Increases in the tensile hold duration degraded the creep fatigue resistance, at least to the investigated strain controlled hold time of up to 60 minutes at the 0.3% strain range and 240 minutes at the 1.0% strain range. The creep fatigue deformation mode is considered relative to the lack of saturation, or continually decreasing number of cycles to failure with increasing hold times. Additionally, preliminary values from the 850°C creep fatigue data are calculated for the creep fatigue damage diagram and have higher values of creep damage than those from tests at 950°C.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Reference constitutive model for Alloy 617 and 316H stainless steel for use with the ASME Division 5 design by inelastic analysis rules

This report describes the development, calibration, and validation of an inelastic constitutive model describing the monotonic, cyclic, and creep behavior of Alloy 617 from room temperature to 983 °C . The model is intended for incorporation into a new Nonmandatory Appendix to Section III, Division 5, Subsection HB, Subpart B of the ASME Boiler & Pressure Vessel Code providing guidance on developing models for use with the ASME design by inelastic analysis provisions as well as a listing of acceptable material models for each Class A material that designers can use without further validation. The report described the development of the A617 model as well as providing an updated draft appendix, ready for ASME ballot, incorporating the A617 and and the previously-developed 316H model. The development of this appendix and the related material models will promote the widespread application of the generally more efficient inelastic analysis rules rules.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2021

Draft Rules for Alloy 617 Creep-Fatigue Design Using an EPP+SMT Approach

The report describes an improved new creep-fatigue design method for structural components in high temperature nuclear service. The new method uses an integrated elastic-perfectly plastic (EPP) analysis and Simplified Model Test (SMT) approach that greatly simplifies the design process by avoiding the separate evaluation of creep and fatigue damages and eliminating the requirement of stress classification. The report includes draft design rules, presented in a format compatible with an ASME nuclear Code Case, as well as a commentary on the rules and the validation of the rules using pressurized SMT (p-SMT) test data. Areas of potential improvement have been identified for further evaluation. The report also develops EPP+SMT design charts for Alloy 617 at temperatures between 800°C and 950°C by extrapolating high strain range, short hold test data to low strain range and long hold times, typical for structural components in high temperature nuclear service. The design charts are currently limited to 10,000 cycles to avoid excessive extrapolation outside the test database. More robust alternate extrapolation procedures will be considered in future work. The report includes several verification problems comparing the new EPP+SMT design method with current ASME creep-fatigue design methods. The comparison demonstrates that the EPP+SMT method significantly reduces the over-conservatism in current methods. Finally, the report includes a fully-documented sample problem with multiple load cases detailing the application of proposed EPP+SMT design rules.

36 MATERIALS SCIENCE↗
DOE OSTI2022

ASME Code Revisions to Incorporate 316H and Alloy 617 Viscoplastic Constitutive Models to Section III, Division 5 and Code Case N-898

This report provides a final status update on work to develop and implement two new constitutive models for 316H stainless steel and the Ni-based Alloy 617 in Nonmandatory Appendix Z to the Section III, Division 5, Subsection HB, Subpart B ASME Boiler & Pressure Vessel Code rules covering the design and construction of Class A high temperature nuclear reactor components. This report summarizes the objections of the overall project and provides the final versions of the constitutive models proposed for incorporation into the ASME Code. The report also provides an update on the balloting status at ASME of the two proposed constitutive models. As of the time of writing (July 2022) the models are on-track to be approved by ASME after the August 2022 Code Week. If so, this will mean the 316H model will be published in the 2023 edition of the Code and the A617 model available as part of a revised Code Case immediately

36 MATERIALS SCIENCE↗
DOE OSTI2024

Corrosion of SS 316, Inconel 617, Inconel 625 in molten chloride salt with emphasis on the speciation of Cr, Ni, and Co in molten salt matrix by XAFS

Dr. Hartmann’ report summarizes the corrosion behavior of materials used in the construction and operation of molten salt reactors which is is of great interest to the molten salt reactor (MSR) community. In the present study we intent to decipher the very elemental phenomena on the corrosion of austenitic chromium-containing stainless steel SS316, as well as Inconel 625 and ASME-coded high temperature Alloy (Inconel) 617. We initiated and are in continuation of conducting ampoule type corrosion testing at 550 °C and 650 °C to determine chromium diffusivity and the related activation energy as well as the speciation of the corrosion products.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Spectral properties of cool stars: Extended abundance analysis of 1,617 planet-search stars

We present a catalog of uniformly determined stellar properties and abundances for 1,617 F, G, and K stars using an automated spectral synthesis modeling procedure. All stars were observed using the HIRES spectrograph at Keck Observatory. Our procedure used a single line list to fit model spectra to observations of all stars to determine effective temperature, surface gravity, metallicity, projected rotational velocity, and the abundances of 15 elements (C, N, O, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, and Y). Sixty percent of the sample had Hipparcos parallaxes and V-band photometry, which we combined with the spectroscopic results to obtain mass, radius, and luminosity. Additionally, we used the luminosity, effective temperature, metallicity and α-element enhancement to interpolate in the Yonsei–Yale isochrones to derive mass, radius, gravity, and age ranges for those stars. Finally, we determined new relations between effective temperature and macroturbulence for dwarfs and subgiants. Our analysis achieved precisions of 25 K in T{sub eff}, 0.01 dex in [M/H], 0.028 dex for logg, and 0.5 km s{sup −1} in vsin i based on multiple observations of the same stars. The abundance results were similarly precise, between ∼0.01 and ∼0.04 dex, though trends with respect to T{sub eff} remained for which we derived empirical corrections. The trends, though small, were much larger than our uncertainties and are shared with published abundances. We show that changing our model atmosphere grid accounts for most of the trend in [M/H] between 5000 and 5500 K, indicating a possible problem with the atmosphere models or opacities.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1982

Radiative properties of a nickel based superalloy: Inconel 617 - After simulated earth reentry

Experimental results are presented to show the effect of environmental simulation exposures of convective heating and of radiant heating on the spectral (1.0 to 14 micrometers) and total emittance of oxidized Inconel 617. Convective heating exposures were conducted in an arc heated supersonic wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted in dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20 and 38 heating cycles of 15-minutes duration and radiant heating specimens were tested for 10, 20, 50 and 100 one-half hour heating cycles. Changes in radiative properties are discussed in terms of changes in composition and morphology resulting from the exposure tests. Total normal emittance did not significantly change from the statically oxidized condition after either type of exposure, and it remained above 0.80 at 1260K for all cases. Although spectral changes were observed on post exposure specimens at wavelengths less than 2.0 micrometers and greater than 15 micrometers, these changes have no influence on total emittance at 1260K.

Cunnington, G. R.↗
DOE OSTI2019

Alloy 800H Weldments with Alloy 617 Filler

Alloy 800H is the leading candidate for the steam generator in Next Generation Nuclear Plant (NGNP) Project. It is necessary to extend the allowable stresses for Alloy 800H to 900 degrees C and 600,000 hours. This also requires data on welds in order to extend code acceptance. The focus of this presentation is on the creep-rupture properties of Alloy 800H cross welds with Alloy 617 filler. The goal is to understand the effect of an overmatched weld on creep-rupture properties.

36 MATERIALS SCIENCE↗
DOE OSTI2023

NOTCH EFFECT ON CREEP-FATIGUE BEHAVIOR OF ALLOY 617 AT ELEVATED TEMPERATURE

High-temperature reactor structural components are often under the complex multiaxial creep-fatigue (CF) loading conditions throughout the lifetime because of geometric and/or metallurgical discontinuities and complex loading paths. To assess the multiaxial CF deformation behavior and to evaluate the CF design rules in the ASME BPVC Section III, Division 5, Subsection HB, Subpart B, experimental and numerical studies are performed on Alloy 617 at 950°C using notch specimen geometries under CF loading in this study.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Single-Bar SMT Testing on Alloy 617 using Software Controls

INL has performed simplified model testing using a variable in the software control program to compare with the testing performed at ORNL, which uses hardware to modify the control signal. The INL tests compared well with the ORNL tests, showing similar stress and strain values, as well as similarly shaped hysteresis loops. This demonstrates that possibility of performing simplified model testing without any hardware modifications.

36 MATERIALS SCIENCE↗