A MULTISCALE CRYSTAL PLASTICITY ANALYSIS OF DEFORMATION IN A TWO-PHASE STEEL

2009 ◽  
Vol 01 (01) ◽  
pp. 1-19 ◽  
Author(s):  
JILLIAN GASKELL ◽  
FIONN DUNNE ◽  
DIDIER FARRUGIA ◽  
JIANGUO LIN
Keyword(s):  
Crystal Plasticity ◽  
Crystallographic Orientation ◽  
Void Nucleation ◽  
Local Stress ◽  
Peak Stress ◽  
Interfacial Stress ◽  
Second Phase ◽  
Two Phase ◽  
Interfacial Stresses ◽  
Crystal Plasticity Model

A rate- and lengthscale-dependent crystal plasticity model is employed with a representative volume element for a two-phase austenitic steel under hot-forming conditions to investigate the role of austenite and MnS particle crystallographic orientation on local stress and slip conditions at austenite–MnS interfaces. It was found that austenite–MnS particle interfacial stress magnifications are determined largely by the crystallographic orientation of the MnS and not significantly by the austenite orientations. However, the crystallographic orientation of an austenite grain neighboring a MnS particle has a dramatic effect on slip localization and slip magnitude in the absence of any significant change in interfacial stress magnitude. The results suggest that it is the crystallographic orientation of the MnS rather than that of the austenite which determines the onset and rapidity of void nucleation. The results also show that there are very particular combinations of austenite–MnS particle orientations which lead to the highest interfacial stresses, and that the peak stress magnification arises not from the properties of the second phase particles but from their orientation. Micromechanical models based on isotropic plasticity will not capture correctly the interfacial stresses.

Composition-induced microstructures in rhombohedral carbonates

1987 ◽  
Vol 51 (359) ◽  
pp. 71-86 ◽  
Author(s):  
D. J. Barber ◽  
M. Riaz Khan
Keyword(s):  
Electron Diffraction ◽  
Crystallographic Orientation ◽  
Solid Solubility ◽  
Single Phase ◽  
Crystal Defects ◽  
Second Phase ◽  
Two Phase ◽  
Diffraction Contrast ◽  
Second Phases ◽  
Metallic Impurities

AbstractRecent TEM observations of two-phase microstructures and associated crystal defects in selected, rare dolomites have been extended to calcite-structured (R3̄c) carbonates and to other natural and synthetic carbonates that crystallize with the dolomite (R3̄) structure. The samples included siderites (FeCO3), smithsonites (ZnCO3), ankerites (Ca[Mg,Fe](CO3)2), and kutnahorites (Ca[Mn,Fe](CO3)2).TEM methods show that the forms of second phases which result from the presence of common, divalent, metallic impurities are morphologically similar in R3̄c and R3̄ carbonates and occur more widely than hitherto realized. The most common form consists of thin ribbons of second phase which are coherent with and have the same crystallographic orientation as the host carbonate. Another form of microstructure, manifest as modulations in diffraction contrast, appears to be associated with incipient breakdown of single-phase carbonate. The results of extensive TEM/EDS microanalyses show that in siderite and ankerite the formation of ribbons is promoted by Ca impurity or Ca excess (with respect to R3̄c stoichiometry). In smithsonite, Cu and Ca impurities can play similar roles in relation to modulated microstructures. In kutnahorites, the perfection of grains and the absence of second-phase effects is strongly dependent on the ratio of Fe to Mn but is also affected by Ca in excess of the stoichiometric requirement. Electron diffraction results from several of the minerals show c-type spots, which can be interpreted as indicating ordering within basal layers of cations.The results show that, by correlating analytical TEM data with the study of second phases and incipient two-phase microstructures, it should be possible to determine the limits of solid solubility in carbonate systems.

Influence of Crystallographic Orientation on Energy Dissipation During Sliding

2007 ◽  
Author(s):  
Jeremy J. Dawkins ◽  
Richard W. Neu
Keyword(s):  
Plastic Deformation ◽  
Energy Dissipation ◽  
Crystal Plasticity ◽  
Crystallographic Orientation ◽  
Crystal Orientation ◽  
Primary Energy ◽  
Homogeneous Material ◽  
Plasticity Model ◽  
Deformation Response ◽  
Crystal Plasticity Model

This work presents the results of a finite element study of the sliding contact of interfering cylindrical asperities. One asperity is modeled as elastic with steel properties, while the other asperity is modeled as elastic-plastic copper. The simulations were run using two different plasticity models for copper, conventional J2 plasticity describing an initially homogeneous material and a continuum crystal plasticity model that can capture the influence of crystallographic orientation on the deformation response. The use of the crystal plasticity model and frictionless contact enables us to study the dependence of plastic deformation and energy dissipation as a function of crystal orientation and vertical interference. The relative trends predicted using crystal plasticity are consistent with classical experiments showing the dependence of friction with crystal orientation when plastic deformation is the primary energy dissipation mechanism.

Analysis of the Necking Behaviors with the Crystal Plasticity Model Using 3-Dimensional Shaped Grains

2013 ◽  
Vol 684 ◽  
pp. 357-361 ◽  
Author(s):  
Jong Bong Kim ◽  
Jeong Whan Yoon
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crystal Plasticity ◽  
Void Nucleation ◽  
Damage Model ◽  
Initial Imperfection ◽  
Plasticity Model ◽  
Element Analysis ◽  
3 Dimensional ◽  
Crystal Plasticity Model

Without initial imperfection and damage evolution model, it is difficult to analyze the necking behavior by finite element analysis with continuum theory. Moreover, the results are greatly dependent on the size of the initial imperfection. In order to predict necking phenomenon without geometric imperfection, in this study, a crystal plasticity model was introduced in the 3-dimensional finite element analysis of tensile test. Grains were modeled by an octahedron and different orientations were allocated to each grain. Damage model was also used to predict the sudden drop of load carrying capacity after necking and to reflect the void nucleation and growth on the severely deformed region. Well-known Cockcroft-Latham damage model was used. Void nucleation, growth and coalescence behavior during necking were predicted reasonably.

Influence of Crystallographic Orientation on Energy Dissipation During Sliding

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Jeremy J. Dawkins ◽  
Richard W. Neu
Keyword(s):  
Finite Element Analysis ◽  
Plastic Deformation ◽  
Energy Dissipation ◽  
Crystal Plasticity ◽  
Crystallographic Orientation ◽  
Grain Orientation ◽  
Primary Energy ◽  
Plasticity Model ◽  
Element Analysis ◽  
Crystal Plasticity Model

The aim of this study is to evaluate a methodology for modeling the influence of crystallographic grain orientation in sliding contacts. The simulations of translating interfering cylindrical asperities, using finite element analysis, were conducted using two different plasticity models for copper: a conventional isotropic, homogeneous J2 plasticity model and a continuum crystal plasticity model. Using crystal plasticity, the dependence of crystallographic orientation on plastic deformation and energy dissipation can be determined. The relative trends predicted using crystal plasticity are consistent with experiments that show friction depends on crystallographic orientation when plastic deformation is one of the primary energy dissipation mechanisms.

A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures

1985 ◽  
Vol 43 ◽  
pp. 70-71
Author(s):  
M.G. Burke ◽  
M.K. Miller
Keyword(s):  
Low Temperature ◽  
Microstructural Characterization ◽  
Superlattice Reflection ◽  
High Volume ◽  
Atom Probe ◽  
Dark Field ◽  
Miscibility Gap ◽  
Second Phase ◽  
Two Phase ◽  
Probe Field

Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

THE DYNAMIC FRACTURE OF TWO PHASE ALLOYS WITH SECOND PHASE INCLUSIONS

1985 ◽  
Vol 46 (C5) ◽  
pp. C5-251-C5-255
Author(s):  
S. Pytel ◽  
L. Wojnar
Keyword(s):  
Dynamic Fracture ◽  
Second Phase ◽  
Two Phase
Sign in / Sign up

Export Citation Format

Share Document