Mechanical And Microstructural Performance Evaluation Of Diffusion Bonded Alloy 800H For Very High Temperature Nuclear Service

2021 ◽  
pp. 1-29
Author(s):  
Heramb Mahajan ◽  
Lucas Maciel ◽  
Tasnim Hassan
Keyword(s):  
High Temperature ◽  
Diffusion Bonding ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Failure Mechanisms ◽  
Bonding Process ◽  
Atomic Diffusion ◽  
Alloy 800H ◽  
Very High

Abstract Very high temperature reactors (VHTRs) are planned to be operated between 550 to 950°C, and demand a thermally efficient intermediate heat exchanger (IHX) in the heat transport system (HTS). The current technological development of compact heat exchangers (CHXs) for VHTRs is at the ‘proof of concept’ level. A significant development in the CHX technologies is essential for the VHTRs to be efficient, cost-effective, and safe. CHXs have very high thermal efficiency and compactness, making them a prime candidate for IHXs in VHTRs. Photochemically etched plates with the desired channel pattern are stacked and diffusion bonded to fabricate CHXs. All plates are compressed at an elevated temperature over a specified period in the diffusion bonding process, promoting atomic diffusion and grain growth across bond surfaces resulting in a monolithic block. The diffusion bonding process changes the base metal properties, which are unknown for Alloy 800H, a candidate alloy for CHX construction. Hence, developing mechanical response data and understanding failure mechanisms of diffusion bonded Alloy 800H at elevated temperatures is a key step for advancing the technology of IHXs in VHTRs. The ultimate goal of this study is to develop ASME BPVC Section III, Division 5 design rules for CHXs in nuclear service. Towards this goal, mechanical performance and microstructures of diffusion bonded Alloy 800H is investigated through a series of tensile, fatigue, creep, and creep-fatigue tests at temperatures 550 to 760°C. The test results, failure mechanisms, and microstructures of diffusion bonded Alloy 800H is scrutinized and presented.

Mechanical and Microstructural Characterization of Diffusion Bonded 800H

2020 ◽  
Author(s):  
Heramb P. Mahajan ◽  
Mohamed Elbakhshwan ◽  
Bruce C. Beihoff ◽  
Tasnim Hassan
Keyword(s):  
Mechanical Property ◽  
Base Metal ◽  
Microstructure Evolution ◽  
Diffusion Bonding ◽  
Elevated Temperatures ◽  
Bonding Process ◽  
Atomic Diffusion ◽  
Alloy 800H ◽  
Tensile Fatigue ◽  
Creep Fatigue

Abstract Compact heat exchangers have high compactness and efficiency, which is achieved by joining a stack of chemically etched channeled plates through diffusion bonding. In the diffusion bonding process, compressive stress is applied on plates at elevated temperatures for a specified period. These conditions lead to atomic diffusion, which results in the joining of all plates into a monolithic block. The diffusion bonding temperatures are above recrystallization temperatures, which changes the mechanical and microstructural properties of the bonded metal. Hence, diffusion bonded material needs mechanical and microstructural property evaluation. In this study, Alloy 800H is selected to study the influence of the diffusion bonding process on mechanical and microstructure properties of base metal. A series of tensile, fatigue, creep, and creep-fatigue experiments are conducted on base metal 800H (BM 800H) and diffusion bonded 800H (DB 800H) to explore the mechanical properties. Microstructure evolution during diffusion bonding is studied and presented in the paper. The mechanical and microstructural observations indicated ductile fracture at room temperature and brittle failure with bond delamination at elevated temperatures. The microstructure evolution during diffusion bonding is studied through tensile, fatigue, creep and creep-fatigue tests, and the implied root causes for the mechanical property changes are investigated. Efforts are made to correlate the microstructure change with mechanical property change in DB 800H.

WIELAND-K88

Alloy Digest ◽  
2005 ◽  
Vol 54 (12) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Stress Relaxation ◽  
Copper Alloy ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Relaxation Resistance ◽  
Temperature Performance ◽  
Very High

Abstract Wieland K-88 is a copper alloy with very high electrical and thermal conductivity, good strength, and excellent stress relaxation resistance at elevated temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CU-738. Producer or source: Wieland Metals Inc.

High Temperature Deformation and Diffusion Brazing of INCONEL 718 Sheet

2014 ◽  
Vol 622-623 ◽  
pp. 508-513
Author(s):  
Yong Nam Kwon ◽  
S.S. Hong ◽  
H.G. Kim
Keyword(s):  
High Temperature ◽  
Diffusion Bonding ◽  
Inconel 718 ◽  
Elevated Temperatures ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Manufacturing Cost ◽  
Lap Shear ◽  
Diffusion Brazing ◽  
And Diffusion

Superplastic forming has been known for the ideal process for manufacturing complex parts. Also, diffusion bonding can give a higher design flexibility, which allows a better performance with a lower overall manufacturing cost. Fine grained INCONEL 718 alloy sheet has been known to show superplastic behavior with the combination of high strength and corrosion resistance at the elevated temperatures. In the present study, high temperature deformation characteristic of INCONEL 718 sheet with 15m was investigated firstly. Then, blow forming process with cylindrical cavity was tried. Also, best diffusion brazing and bonding condition was tried to be defined in terms of temperature, pressure and time. Bonding strength was characterized by using lap shear type test and interface observation. Characteristics of deformation and diffusion bonding at high temperature were influenced greatly with grain size while Nb precipitate also played an important role.

Analysis of the Thermal-Hydraulic and Mechanical Performance of Intermediate Heat Exchangers Used in Systems With Very High Temperature Nuclear Reactors

2018 ◽  
Author(s):  
Raciel de la Torre Valdés ◽  
Juan Luis Francois Lacouture
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Mechanical Performance ◽  
Nuclear Reactors ◽  
Optimized Design ◽  
Solid Region ◽  
Computational Fluid Dynamics Cfd ◽  
The One ◽  
Time Of Operation ◽  
Very High

Intermediate heat exchangers are one of the most critical devices in the safety of facilities with very high temperature nuclear reactors. In this application, the printed circuit heat exchanger (PCHE) design has been the one that has shown the greatest advantages in terms of heat transfer, compaction and structural strength. In this work, a thermal-hydraulic and mechanical model of the PCHE was developed using computational fluid dynamics (CFD) techniques and finite element methods, respectively. The CFD model was validated by comparison with experimental data and empirical correlations of Nusselt number and friction factor published by other authors. A methodology was proposed to evaluate the operation of the exchanger based on the analysis of capital and operating costs. As a relevant aspect of this methodology, the relationship between the maximum Von Misses stress in the structure and the time of operation was considered. In the structural calculations it was observed that increasing the temperature gradient between the channels caused by the increase of the mass flows of gases, causes the displacement of the solid region and the maximum stress increase. The Taguchi method was applied to identify the dimensions that have the greatest influence on the operation of the PCHE and to obtain an optimized design of the device.

HEPPENSTALL C58

Alloy Digest ◽  
1969 ◽  
Vol 18 (1) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
High Temperature ◽  
Physical Properties ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Die Steel ◽  
Temperature Performance ◽  
Alloy Tool ◽  
Very High

Abstract HEPPENSTALL C58 is an alloy tool and die steel furnished in the prehardened and in the annealed conditions. It is used for dies where very high compressive strength and resistance to softening at elevated temperatures are required. This datasheet provides information on composition, physical properties, hardness, and elasticity as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: TS-213. Producer or source: Midvale-Heppenstall Company.

Novel carbon foam composites reinforced with carbon fiber felt developed from inexpensive pitch precursor matrix

2020 ◽  
Vol 54 (24) ◽  
pp. 3559-3569
Author(s):  
Shishobhan Sharma ◽  
Rasmika H Patel
Keyword(s):  
Carbon Fiber ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
Mechanical Performance ◽  
Coal Tar ◽  
Carbon Foam ◽  
Petroleum Pitch ◽  
Gravimetric Analysis ◽  
Carbon Fiber Felt ◽  
Carbon Foams

Novel carbon foam composites derived from various pitch precursors have been fabricated and characterized. This paper specifically focuses on developing an effective process for fabricating the carbon foam composites from Polyacrylonitrile (PAN)-based carbon felt as a reinforcement and various readily available pitch matrix such as petroleum pitch, coal tar pitch, and mesophase pitch. The paper endeavors to develop the carbon foam composites and to carry out detailed morphological, thermal, and mechanical characterization. Traditional carbon foams have been known to offer poor mechanical performance, and hence, in this paper, the pitch-based carbon foams were innovatively reinforced with the PAN-based carbon fiber felt. Carbon foam composites were subjected to partial oxidation, and their morphological and mechanical response after the heat treatment was studied thoroughly. Thermal gravimetric analysis and thermal mechanical analysis techniques reveal an appreciable thermo-physical and thermo-mechanical response at elevated temperatures. Also, it was found out that the factors such as volatile content and quinoline insoluble fraction affect the morphology as well as the physical robustness on the composite foams.

Mechanical Response of T300/BMP350 Composites under Tensile Loading at Room and Elevated Temperatures

2014 ◽  
Vol 1035 ◽  
pp. 138-143
Author(s):  
Ping Zhou ◽  
Pu Rong Jia ◽  
Wen Ge Pan
Keyword(s):  
High Temperature ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
Effect Of Temperature ◽  
Matrix Composites ◽  
Stress Strain ◽  
Damage And Failure ◽  
Different Temperatures ◽  
Static Tensile

In this paper, the effect of elevated temperature on the behavior of carbon fiber-reinforced T300/BMP350 unidirectional laminates was studied by loading static tensile on 0°, 90°and ±45° lay-up. The stress-strain relationships of the laminates under different temperatures were obtained. The effect of temperature on the mechanical properties of materials was systematically studied. The damage and failure mechanisms of the material were studied by analyzing the material stress-strain curves and the failure modes. Results show that the T300/BMP350 polyimide matrix composites have a strong resistance to high temperature. For 0° and 90° lay-up, the retentions of tensile strength and modulus are more than 80% and 50%, respectively. High temperature has little effect on the material failure modes. Finally, based on the test results, an empirical formula which relates strength and temperature of the material was fitted.

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