High Temperature Behavior of Candidate VHTR Heat Exchanger Alloys

2008 ◽  
Author(s):  
Richard Wright ◽  
Joel Simpson ◽  
Alan Wertsching ◽  
W. David Swank
Keyword(s):  
High Temperature ◽  
Good Deal ◽  
Carbon Activity ◽  
Haynes 230 ◽  
Environmental Resistance ◽  
Principal Candidates ◽  
Inconel 617 ◽  
Series Of Experiments ◽  
Term Response

Several nickel based solid solution alloys are under consideration for application in heat exchangers for very high temperature gas cooled reactors. The principal candidates being considered for this application by the Next Generation Nuclear Plant (NGNP) project are Inconel 617 and Haynes 230. While both of these alloys have an attractive combination of creep strength, fabricability, and oxidation resistance a good deal remains to be determined about their environmental resistance in the expected NGNP helium chemistry and their long term response to thermal aging. A series of experiments has been carried out in a He loop with controlled impurity chemistries within the range expected for the NGNP. The influence of oxygen partial pressure and carbon activity on the microstructure and mechanical properties of Alloys 617 and 230 has been characterized. A relatively simple phenomenological model of the environmental interaction for these alloys has been developed.

Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230, and Model Alloys

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Stéphane Gossé ◽  
Thierry Alpettaz ◽  
Sylvie Chatain ◽  
Christine Guéneau
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Mass Spectrometric ◽  
Operating Conditions ◽  
Pure Substance ◽  
Haynes 230 ◽  
Inconel 617 ◽  
High Temperature Reactor ◽  
High Temperature Reactors ◽  
Very High

The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHXs) of (very) high temperature reactors ((V)-HTRs). The behavior under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra- and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. The alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow (Rouillard, F., 2007, “Mécanismes de formation et de destruction de la couche d’oxyde sur un alliage chrominoformeur en milieu HTR,” Ph.D. thesis, Ecole des Mines de Saint-Etienne, France). To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T≈1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617, and model alloys 1178, 1181, and 1201. This coupling makes it possible for the thermodynamic equilibrium to be obtained between the vapor phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared with that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behavior in these alloys. These activity results call into question those previously measured by Hilpert and Ali-Khan (1978, “Mass Spectrometric Studies of Alloys Proposed for High-Temperature Reactor Systems: I. Alloy IN-643,” J. Nucl. Mater., 78, pp. 265–271; 1979, “Mass Spectrometric Studies of Alloys Proposed for High-Temperature Reactor Systems: II. Inconel Alloy 617 and Nimomic Alloy PE 13,” J. Nucl. Mater., 80, pp. 126–131), largely used in the literature.

Direct Measurements of the Chromium Activity in Complex Nickel Base Alloys by High Temperature Mass Spectrometry

2008 ◽  
Vol 595-598 ◽  
pp. 975-985 ◽  
Author(s):  
Stéphane Gossé ◽  
Thierry Alpettaz ◽  
Fabien Rouillard ◽  
Sylvie Chatain ◽  
Christine Guéneau ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Temperature ◽  
Surrounding Medium ◽  
Operating Conditions ◽  
Primary Circuit ◽  
Haynes 230 ◽  
Temperature Range ◽  
High Temperature Mass Spectrometry ◽  
Inconel 617 ◽  
Chromium Activity

Chromium rich, nickel based alloys Haynes 230 and Inconel 617 are candidate materials for the primary circuit and intermediate heat exchangers (IHX) of (Very)-High Temperature Reactors. The corrosion resistance of these alloys is strongly related to the reactivity of chromium in the reactor specific environment (high temperature, impure helium). At intermediate temperature – 900°C for Haynes 230 and 850°C for Inconel 617 – the alloys under investigation are likely to develop a chromium-rich surface oxide scale. This layer protects from the exchanges with the surrounding medium and thus prevents against intensive corrosion processes. However at higher temperatures, it was shown that the surface chromia can be reduced by reaction with the carbon from the alloy [1] and the bare material can quickly corrode. Chromium appears to be a key element in this surface scale reactivity. Then, quantitative assessment of the surface requires an accurate knowledge of the chromium activity in the temperature range close to the operating conditions (T ≈ 1273 K). High temperature mass spectrometry (HTMS) coupled to multiple effusion Knudsen cells was successfully used to measure the chromium activity in Inconel 617 and Haynes 230 in the 1423- 1548 K temperature range. Appropriate adjustments of the experimental parameters and in-situ calibration toward pure chromium allow to reach accuracy better than ± 5%. For both alloys, the chromium activities are determined. Our experimental results on Inconel 617 are in disagreement with the data published by Hilpert [2]. Possible explanations for the significant discrepancy are discussed.

Long-Term Oxidation Behavior of Selected High Temperature Alloys

2007 ◽  
Author(s):  
S. Krishna Srivastava ◽  
Michael J. Newburn ◽  
John P. Cotner ◽  
Mark A. Richeson
Keyword(s):  
High Temperature ◽  
Oxidation Behavior ◽  
Scanning Electron Micrographs ◽  
Corrosion Attack ◽  
Short Term ◽  
Haynes 230 ◽  
High Temperature Alloys ◽  
Oxidation Testing ◽  
Scanning Electron

Long-term oxidation behavior of alloys cannot be estimated reliably by extrapolation of short-term results; therefore long-term testing is imperative. Such data often are not available. Oxidation testing for a period of 360 days has been conducted for several high temperature alloys extensively used in the gas turbine industry. The alloys tested comprised of HASTELLOY® X alloy, HAYNES® 230®, HR-120®, and 214™ alloys, the first three being chromia forming and the last one being an alumina forming alloy. The specimens were exposed to flowing air at 1800°F(982°C), 2000°F(1093°C), 2100°F(1149°C) and 2200°F(1204°C). The tests were interrupted and the specimens were weighed every 30 days. At the completion of each test, the samples were examined metallographically to determine the internal attack. The magnitude of oxidation attack was studied in terms of the weight change and total metal affected. The paper will report the results of the long-term oxidation testing and the analysis of the corrosion attack with the optical and scanning electron micrographs. HASTELLOY, HAYNES, 230 and HR-120 are registered trademarks and 214 is a trademark of Haynes International, Inc.

Analysis of the Flange Seal Groove Cracking in a Hydrocracking Reactor

2020 ◽  
Author(s):  
Fakun Zhuang ◽  
Wen Liu ◽  
Guoshan Xie ◽  
Shanshan Shao ◽  
Zhiyuan Han
Keyword(s):  
High Temperature ◽  
High Stress ◽  
Metallographic Analysis ◽  
Operational Conditions ◽  
Σ Phase ◽  
Term Operation ◽  
Brittle Phase ◽  
Series Of Experiments ◽  
Cracking Tendency

Abstract The hydrocracking reactor, serving at the high temperature and pressure and containing S and N elements in medium, are the key equipment in the hydrocracking plant. Due to the severe operational conditions, flange and nozzle cracking commonly occurs, especially for the seal groove between the flange and gasket. A cracked stainless flange is found in a hydrocracking reactor during parking and maintenance. Through a series of experiments including chemical composition, metallographic analysis, SEM and fracture analysis, the flange seal groove is analyzed. Under the long term operation at high temperature and high pressure, the σ phase is found in the flange material which will increase the cracking tendency. The hydrogen content measurement also proves that the material has the hydrogen embrittlement tendency. Hence, the combination of σ brittle phase and high stress causes the flange seal groove cracking. After cracking, hydrogen element enters the fracture, thus accelerating the crack growth. Therefore, in order to prevent the flange cracking, the assembly stress should be controlled in an appropriate range. If necessary, periodical inspection must be performed.

Comparison of the High Temperature Surface Reactivity in Impure Helium of Two Materials for Gas Cooled Reactors

2008 ◽  
Vol 595-598 ◽  
pp. 439-448 ◽  
Author(s):  
Céline Cabet ◽  
Gouenou Girardin ◽  
Fabien Rouillard ◽  
Jerome Chapovaloff ◽  
Krzysztof Wolski ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
High Temperature ◽  
Surface Reactivity ◽  
Haynes 230 ◽  
Partial Pressures ◽  
Basic Equilibrium ◽  
Inconel 617 ◽  
Nickel Base ◽  
Temperature Surface

Nickel base alloys Haynes 230 and Inconel 617 are of interest for gas cooled reactors. At high temperature in impure helium, they generally form surface chromium-rich oxides. However above a critical temperature called TA, the scales are not stable anymore and the chromia destruction comes with a production of carbon monoxide. Reactivity tests on model alloys, with and without carbon, prove that chromia is reduced by the carbon from the alloy. TA vs P(CO) curves were also plotted for the two commercial alloys based on the experimental determination of TA in various atmospheres with increasing partial pressures of carbon monoxide. Unexpectedly, both materials exhibit an almost identical behavior although a basic equilibrium approach suggests that the chromia scale would be reduced in different conditions due to the thermodynamic particularity of the interfacial alloy/scale system.

Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230 and Model Alloys

2008 ◽  
Author(s):  
S. Gosse´ ◽  
T. Alpettaz ◽  
S. Chatain ◽  
C. Gue´neau ◽  
F. Rouillard ◽  
...  
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Selection Criterion ◽  
Operating Conditions ◽  
Pure Substance ◽  
Protective Oxide ◽  
Haynes 230 ◽  
Activity Measurements ◽  
Inconel 617 ◽  
Very High

The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHX) of (V)-HTR reactors. The behaviour under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. Then, the alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow [1]. To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T ≈ 1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617 and model alloys 1178, 1181, 1201. This coupling makes it possible thermodynamic equilibrium to be obtained between the vapour phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared to that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behaviour in these alloys. These activity results call into question those previously measured by Hilpert [2], largely used in the literature.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

KUBOTA KNC-03

Alloy Digest ◽  
2010 ◽  
Vol 59 (1) ◽  
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Strength ◽  
Temperature Performance ◽  
Resistance To Oxidation

Abstract Kubota KNC-03 is a grade with a combination of high strength and excellent resistance to oxidation. These properties make this alloy suitable for long-term service at temperature up to 1250 deg C (2282 deg F). This datasheet provides information on physical properties, hardness, elasticity, tensile properties, and compressive strength as well as creep. It also includes information on high temperature performance as well as casting and joining. Filing Code: Ni-676. Producer or source: Kubota Metal Corporation, Fahramet Division. See also Alloy Digest Ni-662, April 2008.

ATI 6-2-4-2

Alloy Digest ◽  
2020 ◽  
Vol 69 (8) ◽  
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
High Temperature ◽  
Creep Strength ◽  
High Strength ◽  
Heat Treating ◽  
Good Combination ◽  
Long Term Stability ◽  
Temperature Performance

Abstract ATI 6-2-4-2 is a near-alpha, high strength, titanium alloy that exhibits a good combination of tensile strength, creep strength, toughness, and long-term stability at temperatures up to 425 °C (800 °F). Silicon up to 0.1% frequently is added to improve the creep resistance of the alloy. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ti-169. Producer or Source: ATI.

scholarly journals CO Detection Investigation at High Temperature by SiC MISFET Metal/Oxide Gas Sensors

Proceedings ◽  
2021 ◽  
Vol 56 (1) ◽  
pp. 41
Author(s):  
Lida Khajavizadeh ◽  
Anita Lloyd Spetz ◽  
Mike Andersson
Keyword(s):  
High Temperature ◽  
Gas Sensors ◽  
Elevated Temperatures ◽  
Long Term Stability ◽  
Stability Performance ◽  
Catalytic Metal ◽  
Co Detection ◽  
Effect Transistor ◽  
Metal Oxide Gas Sensors

In order to investigate the necessary device improvements for high-temperature CO sensing with SiC metal insulator semiconductor field effect transistor (MISFET)-based chemical gas sensors, devices employing, as the gas-sensitive gate contact, a film of co-deposited Pt/Al2O3 instead of the commonly used catalytic metal-based contacts were fabricated and characterized for CO detection at elevated temperatures and different CO and O2 levels. It can be concluded that the sensing mechanism at elevated temperatures correlates with oxygen removal from the sensor surface rather than the surface CO coverage as observed at lower temperatures. The long-term stability performance was also shown to be improved compared to that of previously studied devices.

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