Quantitative Study of Residual Strain and Geometrically Necessary Dislocation Density Using HR-EBSD Method

2021 ◽  
Author(s):  
C. Zhao ◽  
X. Li
Keyword(s):  
Dislocation Density ◽  
Quantitative Study ◽  
Residual Strain ◽  
Geometrically Necessary Dislocation ◽  
Ebsd Method

Length-Scale-Dependent Micromechanical Modeling for Precipitate Hardening in Inconel 718 Superalloy

2021 ◽  
Vol 315 ◽  
pp. 84-89
Author(s):  
Chang Feng Wan ◽  
Dong Feng Li ◽  
Hai Long Qin ◽  
Ji Zhang ◽  
Zhong Nan Bi
Keyword(s):  
Dislocation Density ◽  
Strain Gradient ◽  
Inconel 718 ◽  
Micromechanical Modeling ◽  
Fe Model ◽  
Gradient Effect ◽  
Fine Mesh ◽  
Geometrically Necessary Dislocation ◽  
In718 Superalloy ◽  
Inconel 718 Superalloy

In this paper, a micromechanical finite element (FE) model has been proposed to investigate the effect of the nanoscale precipitates on the development of microplasticity for Inconel 718 (IN718) superalloy. A strain gradient crystal plasticity formulation has been developed with the considerations of the evolution of statistically stored dislocation density and geometrically necessary dislocation density. The mesh convergence has been examined, showing that sufficiently fine mesh is required in the FE model. The results show that the model with strain gradient effect incorporated shows less peak plastic strain and higher value of dislocation density than the model with no strain gradient effect. The present study indicates that the strain hardening process at the scale of strengthening precipitate is mainly governed by the evolution of geometrically necessary dislocation densities.

Experimental lower bounds on geometrically necessary dislocation density

2010 ◽  
Vol 26 (8) ◽  
pp. 1097-1123 ◽  
Author(s):  
J.W. Kysar ◽  
Y. Saito ◽  
M.S. Oztop ◽  
D. Lee ◽  
W.T. Huh
Keyword(s):  
Dislocation Density ◽  
Lower Bounds ◽  
Geometrically Necessary Dislocation

Analytical Prediction of Geometrically Necessary Dislocation Density during Plane Strain Microbending

2016 ◽  
Vol 693 ◽  
pp. 734-739 ◽  
Author(s):  
Li Jie Wang ◽  
Brad L. Kinsey ◽  
Sunal Parasiz
Keyword(s):  
Dislocation Density ◽  
Plane Strain ◽  
Analytical Model ◽  
Cross Section ◽  
Strain Gradient ◽  
Analytical Prediction ◽  
Feature Size ◽  
Strain Gradients ◽  
Geometrically Necessary Dislocation ◽  
The Cross

As components with proportional feature and tooling sizes are miniaturized, strain gradients through the cross-section increase. This causes strain gradient hardening as the density of geometrically necessary dislocations increases. This will lead to higher required forces in the process than expected. In this paper, an analytical model to predict the dislocation density increases, and thus strain gradient hardening, during microbending is presented. These results match previous research in terms of the feature size where modest and significant strain gradient hardening was observed.

scholarly journals Behaviour of crystalline–amorphous interfaces in energetic aggregates subjected to coupled thermomechanical and laser loading

2015 ◽  
Vol 471 (2184) ◽  
pp. 20150548
Author(s):  
Judith A. Brown ◽  
M. A. Zikry
Keyword(s):  
Dislocation Density ◽  
High Strain ◽  
Polymer Binder ◽  
Static Compression ◽  
Stress Gradients ◽  
Geometrically Necessary Dislocation ◽  
Compression Behaviour ◽  
Dislocation Densities ◽  
Defect Nucleation ◽  
Quasi Static Compression

The behaviour of energetic aggregates was investigated for quasi-static compression and high strain rate thermomechanical compression behaviour that is coupled to laser irradiation. A dislocation-density-based crystal plasticity formulation was used to represent energetic crystalline behaviour, a finite viscoelastic formulation was used for the polymer binder and a coupled electromagnetic (EM)–thermomechanical computational scheme was used to predict aggregate response. Aggregates with different crystal sizes were considered to account for physically representative energetic microstructures and to understand the effects of crystal–crystal and crystal–binder interactions. The presence of smaller embedded crystals in the binder ligaments inhibited viscous sliding, and resulted in global hardening of the aggregate, which led to large stress gradients, localized plasticity and dislocation-density accumulation. The embedded crystals also increased scattering of the EM wave within the binder ligaments and increased the localization of EM energy and laser heat generation. Geometrically, necessary dislocation densities and stress gradients were calculated to characterize how hardening at the binder interfaces can lead to strengthening or defect nucleation.

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