Microstructure and Strength Characteristics of Alloy 617 Welds

Totemeier, T. C.; Tian, Hui; Clark, Dean S.; Simpson, J. A.

doi:10.2172/911266

Cited by 19 publications

(20 citation statements)

References 4 publications

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“…The IHX have to be joined to piping or other components by welding technique. Very high temperature deformation is expected to be a predominant failure mechanism of the IHX, and thus, weldments used in its fabrication experience varying cyclic deformation and are a key element of all designs [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…In this circumstance, the low cycle fatigue (LCF) loadings represent a predominant failure mode from the temperature gradient induced thermal strain during operation as well as in the startups and shutdowns and in power transients or with temperature change of the flowing coolant having a low loading rate [5][6][7][8]. Because of these shortcomings, significant consideration of LCF behavior is needed in the design and life assessment of such components working in high temperature conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Experience with nickel alloy weldments in structural applications suggests that most cases of high temperature fatigue failures occur at the weldments or in the heat affected zone (HAZ) [6]. Although Alloy 617 has many superior properties, numerous researchers have reported that the fatigue life varies widely at high temperature and it is generally found that the weldment specimens have a lower fatigue life compared to the base metal, although only limited data were available on the weldments material [5][6][7][8][9][10][11]. A draft Code Case was developed to qualify the Alloy 617 for nuclear service; the need for fatigue data, such as the influence of strain ranges, strain rate, and temperature at thermally induced strain rates in the IHX parent material and weldments material is necessary to predict the lifetime of the reactor components.…”

Section: Introductionmentioning

confidence: 99%

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Understanding Low Cycle Fatigue Behavior of Alloy 617 Base Metal and Weldments at 900 °C

Dewa

Kim

et al. 2016

Metals

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Abstract:In order to better understand the high temperature low cycle fatigue behavior of Alloy 617 weldments, this work focuses on the comparative study of the low cycle fatigue behavior of Alloy 617 base metal and weldments, made from automated gas tungsten arc welding with Alloy 617 filler wire. Low cycle fatigue tests were carried out by a series of fully reversed strain-controls (strain ratio, R ε =´1), i.e., 0.6%, 0.9%, 1.2% and 1.5% at a high temperature of 900˝C and a constant strain rate of 10´3/s. At all the testing conditions, the weldment specimens showed lower fatigue lives compared with the base metal due to their microstructural heterogeneities. The effect of very high temperature deformation behavior regarding cyclic stress response varied as a complex function of material property and total strain range. The Alloy 617 base weldments showed some cyclic hardening as a function of total strain range. However, the Alloy 617 base metal showed some cyclic softening induced by solute drag creep during low cycle fatigue. An analysis of the low cycle fatigue data based on a Coffin-Manson relationship was carried out. Fracture surface characterizations were performed on selected fractured specimens using standard metallographic techniques.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Understanding Low Cycle Fatigue Behavior of Alloy 617 Base Metal and Weldments at 900 °C

Dewa

Kim

et al. 2016

Metals

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“…The difficulty comes in the solid state reactions that occur during welding or in service (Dupont, Lippold, & Kiser, 2009), (Totemeier, Tian, Clark, & Simpson, 2005). Intermetallic compounds can form that are brittle and allow the joint to fracture with low energy; typically these can be predicted from phase diagrams.…”

Section: Dissimilar Metal Joiningmentioning

confidence: 99%

Diffusion Welding of Alloys for Molten Salt Service - Status Report

Clark¹,

Mizia²

2012

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This report addresses present work concerned with heat exchanger development for molten salt service, including the AHTR (Advanced High Temperature Reactor), which uses molten salt for cooling and process heat transfer. These results are an outgrowth of recent work done under the Next Generation Nuclear Plant (NGNP) Project, which was concerned with the diffusion welding of Alloys 800H, 617, and similar materials for oxidation resistance at operating temperatures up to 900°C. The molten salt systems discussed herein use other alloys such as Alloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, typically at 1150°C for 3 hours under applied loads of ~5 MPa using the Gleeble thermo-mechanical testing machine. Thermocalc/DICTRA models were developed to predict diffusion, and compositions of welds with a 15 µm nickel foil interlayer were measured after welding for comparison. Calculated and experimental values were in good agreement. Test specimens were prepared for exposing diffusion welds to molten salt environments. Alloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values.

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“…36 . In the absence of an IHX design, the joints produced and studied in this program were "typical" for the alloy, i.e., joining parameters that are those commonly used in industry and dimensions are those convenient for production of test specimens.…”

Section: [ ] 35mentioning

confidence: 99%

Next Generation Nuclear Plant Materials Research and Development Program Plan

Hayner¹,

Bratton²,

Wright³

2005

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The U.S Department of Energy (DOE) has selected the Very High Temperature Reactor (VHTR) design for the Next Generation Nuclear Plant (NGNP) Project. The NGNP will demonstrate the use of nuclear power for electricity and hydrogen production without greenhouse gas emissions. The reactor design will be a graphite moderated, helium-cooled, prismatic or pebble-bed, thermal neutron spectrum reactor that will produce electricity and hydrogen in a state-of-the-art thermodynamically efficient manner. The NGNP will use very high burn-up, low-enriched uranium, TRISO-coated fuel and have a projected plant design service life of 60 years.The VHTR concept is considered to be the nearest-term reactor design that has the capability to efficiently produce hydrogen. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during accidents. The NGNP Project is envisioned to demonstrate the following:A full-scale prototype VHTR by about 2021High-temperature Brayton Cycle electric power production at full scale with a focus on economic performance Nuclear-assisted production of hydrogen (with about 10% of the heat) with a focus on economic performance By test, the exceptional safety capabilities of the advanced gas-cooled reactors. Developing a specific approach, program plan and other project management tools for managing the R&D program elements Developing a specific work package for the R&D activities to be performed during each government fiscal year Reporting the status and progress of the work based on committed deliverables and milestones Developing collaboration in areas of materials R&D of benefit to the NGNP with countries that are a part of the Generation IV International ForumEnsuring that the R&D work performed in support of the materials program is in conformance with established Quality Assurance and procurement requirements iii The objective of the NGNP Materials R&D Program is to provide the essential materials R&D needed to support the design and licensing of the reactor and balance of plant, excluding the hydrogen plant. The materials R&D program is being initiated prior to the design effort to ensure that materials R&D activities are initiated early enough to support the design process and support the Project Integrator. The thermal, environmental, and service life conditions of the NGNP will make selection and qualification of some high-temperature materials a significant challenge; thus, new materials and approaches may be required. The following materials R&D program areas are currently addressed in the R&D program being performed or planned:Qualification and testing of nuclear graphite and carbon fiber/carbon matrix composites for use in the NGNP. These components are essential to any VHTR design and the irradiation induced dimensional and material property changes must be properly modeled.Development of improved high-temperature design methodologies for application toward the further development, qualification, ...

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Microstructure and Strength Characteristics of Alloy 617 Welds

Cited by 19 publications

References 4 publications

Understanding Low Cycle Fatigue Behavior of Alloy 617 Base Metal and Weldments at 900 °C

Understanding Low Cycle Fatigue Behavior of Alloy 617 Base Metal and Weldments at 900 °C

Diffusion Welding of Alloys for Molten Salt Service - Status Report

Next Generation Nuclear Plant Materials Research and Development Program Plan

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