An Unified Constitutive Model With Optimized Parameters for Base and Diffusion Bonded Alloy 800h

2021 ◽  
Author(s):  
Heramb Mahajan ◽  
Tasnim Hassan
Keyword(s):  
Constitutive Model ◽  
Alloy 800H ◽  
And Diffusion

A Dislocation Density Based Constitutive Model for Cyclic Deformation

1996 ◽  
Vol 118 (4) ◽  
pp. 441-447 ◽  
Author(s):  
Y. Estrin ◽  
H. Braasch ◽  
Y. Brechet
Keyword(s):  
Cyclic Loading ◽  
Dislocation Density ◽  
Constitutive Model ◽  
Constitutive Equations ◽  
Cyclic Deformation ◽  
Internal Variables ◽  
Density Evolution ◽  
Alloy 800H ◽  
Material Response ◽  
Dislocation Densities

A new constitutive model describing material response to cyclic loading is presented. The model includes dislocation densities as internal variables characterizing the microstructural state of the material. In the formulation of the constitutive equations, the dislocation density evolution resulting from interactions between dislocations in channel-like dislocation patterns is considered. The capabilities of the model are demonstrated for INCONEL 738 LC and Alloy 800H.

A Unified Constitutive Model With Optimized Parameters for Base and Diffusion Bonded Alloy 800H

2020 ◽  
Author(s):  
Heramb P. Mahajan ◽  
Tasnim Hassan
Keyword(s):  
Elevated Temperature ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Constitutive Model ◽  
Nuclear Power ◽  
Parameter Determination ◽  
Alloy 800H ◽  
Inelastic Analysis ◽  
Creep Fatigue ◽  
Plant Components

Abstract Current ASME Section III, Division 5 code provides elastic, simplified inelastic and inelastic analysis options for designing nuclear power plant components for elevated temperature service. These analyses methods may fail to capture the complex creep-fatigue response and damage accumulation in materials at elevated temperatures. Hence, for analysis and design of the nuclear power plant components at elevated temperature, a full inelastic analysis that can simulate creep-fatigue responses may be needed. Existing ASME code neither provides guidelines for using full inelastic analysis nor recommends the type of constitutive model to be used. Hence, a unified rate-dependent constitutive model incorporating a damage parameter will be developed, and its parameters for base metal will be determined. In addition, a full inelastic analysis methodology using this model to analyze the creep-fatigue performance of components for nuclear power applications will be developed. Base metal 800H (BM800H) data are collected from literature to determine constitutive material model parameters. The parameter determination methodology for a constitutive model is discussed. The optimized parameter set for BM 800H at different temperatures will be presented in the paper. Recommendations are provided on the constitutive model selection and its parameter determination techniques. In the future, this work will be continued for diffusion bonded Alloy 800H (DB800H) material, and obtained parameters will be compared.

Hot Deformation Behavior and Constitutive Modeling of Alloy 800H Considering Effectsof Strain

2017 ◽  
Vol 36 (5) ◽  
pp. 467-475
Author(s):  
Rui Luo ◽  
Qi Zheng ◽  
Zhending Tang ◽  
Yongquan Yao ◽  
Guifang Xu ◽  
...  
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Testing Machine ◽  
Experimental Result ◽  
Strain Rates ◽  
Hot Deformation Behavior ◽  
Alloy 800H ◽  
Strain Dependent

AbstractHigh-temperature single-pass compression experiments were conducted on alloy 800H using a Gleeble 3500 thermal-mechanical simulation testing machine, and hot deformation behaviors at temperatures of 1,000–1,150 °C and strain rates of 0.01–1 s–1 were investigated. The results revealed that dynamic recrystallization (DRX) behavior occurred more easily under deformation conditions with relatively low strain rates and high deformation temperatures. By taking the influence of strain on the hot deformation behavior into consideration, a strain-dependent hyperbolic sine constitutive model was constructed. Based on this revised constitutive model, flow stress during deformation was predicted. The linear relation between the predicted value and the experimental result was as high as 0.99648, and the absolute average relative error was 2.019 %. Thus, it was demonstrated that the strain-dependent analysis provided a constitutive model that was able to precisely predict flow stress under experimental conditions.

Meridional Circulation, Turbulence, and Diffusion Processes in Stars

1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair
Keyword(s):  
Convection Zone ◽  
Diffusion Processes ◽  
Meridional Circulation ◽  
Diffusion Time ◽  
Work In Progress ◽  
First Results ◽  
Stellar Envelopes ◽  
And Diffusion ◽  
Turbulence And Diffusion ◽  
Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

Ordering and diffusion in II-VI/III-VI alloys with structural vacancies

1997 ◽  
Vol 101-103 (1-2) ◽  
pp. 479-487
Author(s):  
H v. Wensierski
Keyword(s):  
And Diffusion
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