scholarly journals Measuring method of plastic strain using grain boundary as a contour pattern.

1990 ◽  
Vol 56 (521) ◽  
pp. 146-149
Author(s):  
Hitoshi MORITOKI ◽  
Shinzou NISHIMURA ◽  
Akihiro ASAKAWA ◽  
Yoshiki TSUKAMOTO ◽  
Mutsuo WATANABE ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Grain Boundary ◽  
Measuring Method ◽  
Contour Pattern

scholarly journals Equivalent plastic strain gradient plasticity with grain boundary hardening and comparison to discrete dislocation dynamics

2015 ◽  
Vol 471 (2184) ◽  
pp. 20150388 ◽  
Author(s):  
E. Bayerschen ◽  
M. Stricker ◽  
S. Wulfinghoff ◽  
D. Weygand ◽  
T. Böhlke
Keyword(s):  
Plastic Strain ◽  
Yield Strength ◽  
Grain Boundary ◽  
Continuum Model ◽  
Equivalent Plastic Strain ◽  
Elastic Interaction ◽  
Dislocation Dynamics ◽  
Discrete Dislocation Dynamics ◽  
Discrete Dislocation ◽  
The Continuum

The gradient crystal plasticity framework of Wulfinghoff et al. (Wulfinghoff et al. 2013 Int. J. Plasticity 51, 33–46. ( doi:10.1016/j.ijplas.2013.07.001 )), incorporating an equivalent plastic strain γ eq and grain boundary (GB) yielding, is extended with GB hardening. By comparison to averaged results from many discrete dislocation dynamics (DDD) simulations of an aluminium-type tricrystal under tensile loading, the new hardening parameter of the continuum model is calibrated. Although the GBs in the discrete simulations are impenetrable, an infinite GB yield strength, corresponding to microhard GB conditions, is not applicable in the continuum model. A combination of a finite GB yield strength with an isotropic bulk Voce hardening relation alone also fails to model the plastic strain profiles obtained by DDD. Instead, a finite GB yield strength in combination with GB hardening depending on the equivalent plastic strain at the GBs is shown to give a better agreement to DDD results. The differences in the plastic strain profiles obtained in DDD simulations by using different orientations of the central grain could not be captured. This indicates that the misorientation-dependent elastic interaction of dislocations reaching over the GBs should also be included in the continuum model.

On the Relationship Between Grain Boundary Sliding and Intragranular Slip During Superplastic Deformation

1999 ◽  
Vol 601 ◽  
Author(s):  
A. D. Sheikh-Ali ◽  
J. A. Szpunar ◽  
H. Garmestani
Keyword(s):  
Plastic Strain ◽  
Grain Boundary ◽  
Superplastic Deformation ◽  
Theoretical Estimate ◽  
Grain Boundary Sliding ◽  
Polycrystalline Materials ◽  
Boundary Sliding ◽  
The Relationship

AbstractThis paper examines grain boundary sliding under the conditions of plastic strain incompatibility that is the most frequent case in polycrystalline materials. Two components of grain boundary sliding: dependent and independent on intragranular slip are distinguished. Theoretical estimate of a ratio between slip induced sliding and intragranular slip is obtained. It is concluded that slip and sliding are rather independent than interrelated processes.

Plastic strain-induced grain boundary migration (SIBM) in pure aluminum: SEM in-situ and AFM examinations

2019 ◽  
Vol 115 ◽  
pp. 29-55 ◽  
Author(s):  
B. Beucia ◽  
S. Queyreau ◽  
C. Kahloun ◽  
D. Chaubet ◽  
P. Franciosi ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Pure Aluminum ◽  
Grain Boundary Migration

Sensitivity to Fatigue Cracks Initiation of Symmetrical Tilt Grain Boundaries in Pure Copper Bicrystals in 1M NaNO2 Solution

2007 ◽  
Vol 561-565 ◽  
pp. 2415-2418
Author(s):  
Hiroyuki Miyamoto ◽  
K. Kuroda ◽  
Takura Mimaki
Keyword(s):  
Plastic Strain ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Fatigue Cracks ◽  
Pure Copper ◽  
Large Angle ◽  
Compression Tests ◽  
High Susceptibility ◽  
Axial Tension ◽  
Pile Up

Sensitivity to corrosion fatigue (CF) crack initiation has been investigated in a series of pure copper bicrystals with a symmetrical <110>-tilt grain boundary. Tests were performed by axial tension-compression tests in 1M NaNO2 solutions. The small-angle tilt bicrystals fractured in both intergranular and transgranular manners accompanied by a large amount of plastic strain to fracture while the large-angle bicrystals fractured in almost intergranular manner with a smaller plastic strain. Susceptibility to CF cracks increases with increasing misorientation. It seems that effect of grain boundaries structures, i.e., Σ-values is small in this experiment. Stress concentration generated by the pile-up of trapped dislocations at the grain boundary could account for the high susceptibility of the intergranular cracks in large-angle grain boundaries

Effects of Grain Size on Crack Tip Mechanical Fields of Intergranular Cracking

2014 ◽  
Vol 1004-1005 ◽  
pp. 1147-1151
Author(s):  
Wei Bing Wang ◽  
He Xue ◽  
Fu Qiang Yang ◽  
Kun Liu
Keyword(s):  
Grain Size ◽  
Plastic Strain ◽  
Grain Boundary ◽  
Principal Stress ◽  
Power Plants ◽  
Equivalent Plastic Strain ◽  
Crack Tip ◽  
Maximum Principal Stress ◽  
Macroscopic Model ◽  
Intergranular Cracking

Intergranular stress corrosion cracking is one of important failure form of structural materials in nuclear power plants, and the initiation and development of crack at grain boundary are affected by the grain size of materials. The macroscopic model and mesoscopic model of crack propagation was established by using finite element method, and the effects of grain size on fracture parameters such as Mises stress, the maximum principal stress and equivalent plastic strain nearby crack tip were studied. The results indicate that the distribution of Mises stress and equivalent plastic strain are discontinuity at grain boundary, and the maximum principal stress locates at grain boundary. The Mises stress, maximum principal stress and equivalent plastic strain nearby crack tip increase with the increasing of grain size.

scholarly journals Coupling a discrete twin model with cohesive elements to understand twin-induced fracture

2021 ◽  
Vol 227 (2) ◽  
pp. 173-192
Author(s):  
Nicolò Grilli ◽  
Edmund Tarleton ◽  
Alan C. F. Cocks
Keyword(s):  
Plastic Strain ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Crack Nucleation ◽  
Zone Model ◽  
Cohesive Elements ◽  
Strain Concentration ◽  
Twin Model

Abstract The interplay between twinning and fracture in metals under deformation is an open question. The plastic strain concentration created by twin bands can induce large stresses on the grain boundaries. We present simulations in which a continuum model describing discrete twins is coupled with a crystal plasticity finite element model and a cohesive zone model for intergranular fracture. The discrete twin model can predict twin nucleation, propagation, growth and the correct twin thickness. Therefore, the plastic strain concentration in the twin band can be modelled. The cohesive zone model is based on a bilinear traction-separation law in which the damage is caused by the normal stress on the grain boundary. An algorithm is developed to generate interface elements at the grain boundaries that satisfy the traction-separation law. The model is calibrated by comparing polycrystal simulations with the experimentally observed strain to failure and maximum stress. The dynamics of twin and crack nucleation have been investigated. First, twins nucleate and propagate in a grain, then, microcracks form near the intersection between twin tips and grain boundaries. Microcracks appear at multiple locations before merging. A propagating crack can nucleate additional twins starting from the grain boundary, a few micrometres away from the original crack nucleation site. This model can be used to understand which type of texture is more resistant against crack nucleation and propagation in cast metals in which twinning is a deformation mechanism. The code is available online at https://github.com/TarletonGroup/CrystalPlasticity. Graphic Abstract

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

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