Unrecoverable Strain Hardening in Torsionally Strained OFHC Copper

1990 ◽  
Vol 112 (3) ◽  
pp. 315-320 ◽  
Author(s):  
D. P. Field ◽  
B. L. Adams
Keyword(s):  
Crystal Lattice ◽  
Shear Strain ◽  
Strain Hardening ◽  
Texture Evolution ◽  
Lattice Rotation ◽  
Ofhc Copper ◽  
Softening Effect ◽  
Recoverable Strain ◽  
Torsional Strain ◽  
Shear Strains

This paper investigates the recoverable and unrecoverable components of strain hardening in OFHC copper tubing subjected to torsional strain. Individual hardening components are classified and the magnitude of each is experimentally determined. Recoverable strain hardening is defined to be the difference between the final shear stress and the yield stress measured after recovery annealing. The recoverable hardening, due primarily to dislocation pileups, accounts for about 95.5 percent of the measured strain hardening at a shear strain of 1.9. Crystal lattice rotation during shear strain accounts for a portion of the unrecoverable hardening at shear strains less than .25, but becomes a strain softening effect at shear strains above .5. The evolution of the texture is measured experimentally and analyzed using both Taylor’s and Kochendorfer’s models. Texture evolution is also simulated up to a shear strain of 2.0 using Taylor’s model. This simulation yields similar results to the measured texture in determining strain hardening caused by rotation of the crystal lattice. The softening effect of crystalline reorientation accounts for a decrease in the observable hardening of 1.5 percent at a shear strain of 1.9.

Shear Banding in Polycrystalline Aluminium and Copper Pre-Deformed by ECAP and Subsequently Plane Strain Compressed

2016 ◽  
Vol 716 ◽  
pp. 240-247
Author(s):  
Henryk Paul ◽  
Magdalena M. Miszczyk
Keyword(s):  
Crystal Lattice ◽  
Grain Boundaries ◽  
Texture Evolution ◽  
Shear Banding ◽  
Shear Bands ◽  
Shear Plane ◽  
Lattice Rotation ◽  
Pure Aluminium ◽  
Electron Backscattered Diffraction ◽  
Angular Pressing

The microstructure and texture evolution in commercially pure aluminium (AA1050 alloy) and copper have been characterized after change in strain path to elucidate the mechanisms of shear bands (SBs) formation and propagation across grain boundaries. Samples were pre-deformed in equal channel angular pressing (ECAP) and further compressed in a channel-die to form two sets of macro-SBs. The deformation-induced sub-structures and local changes in crystallographic orientations were characterized by scanning electron microscopy equipped with a high-resolution electron backscattered diffraction facility. It was found that the mechanism of micro-/macro-SBs formation is strictly crystallographic. In all the grains of the sheared zone a strong tendency to strain-induced re-orientation could be observed. Their crystal lattice rotated in such a way that one of the {111} slip planes became nearly parallel to the shear plane and the <011> (or <112>) direction became parallel to the direction of maximum shear. This crystal lattice rotation led to the formation of specific SBs components which facilitates slip propagation across grain boundaries without any visible variation in the slip direction.

An Sem/Ebsd Study of Shear Bands Formation in Al-0.23%wt.Zr Alloy Deformed in Plane Strain Compression / Krystalograficzne Aspekty Formowania Sie Pasm Scinania W Stopie Al-0.23%Wag.Zr Odkształcanym W Próbie Nieswobodnego Sciskania

2013 ◽  
Vol 58 (1) ◽  
pp. 145-150 ◽  
Author(s):  
H. Paul ◽  
P. Uliasz ◽  
M. Miszczyk ◽  
W. Skuza ◽  
T. Knych
Keyword(s):  
Crystal Lattice ◽  
Grain Boundaries ◽  
Texture Evolution ◽  
Shear Bands ◽  
Shear Direction ◽  
Face Centered Cubic ◽  
Electron Backscattered Diffraction ◽  
Cubic Metals ◽  
Slip Planes ◽  
Face Centered

The crystal lattice rotations induced by shear bands formation have been examined in order to investigate the influence of grain boundaries on slip propagation and the resulting texture evolution. The issue was analysed on Al-0.23wt.%Zr alloy as a representative of face centered cubic metals with medium-to-high stacking fault energy. After solidification, the microstructure of the alloy was composed of flat, twin-oriented, large grains. The samples were cut-off from the as-cast ingot in such a way that the twinning planes were situated almost parallel to the compression plane. The samples were then deformed at 77K in channel-die up to strains of 0.69. To correlate the substructure with the slip patterns, the deformed specimens were examined by SEM equipped with a field emission gun and electron backscattered diffraction facilities. Microtexture measurements showed that strictly defined crystal lattice re-orientations occurred in the sample volumes situated within the area of the broad macroscopic shear bands (MSB), although the grains initially had quite different crystallographic orientations. Independently of the grain orientation, their crystal lattice rotated in such a way that one of the f111g slip planes became nearly parallel to the plane of maximum shear. This facilitates the slip propagation across the grain boundaries along the shear direction without any visible variation in the slip plane. A natural consequence of this rotation is the formation of specific MSB microtextures which facilitates slip propagation across grain boundaries.

Characterization of Plastic Deformation Induced by Microscale Laser Shock Peening

2004 ◽  
Vol 71 (5) ◽  
pp. 713-723 ◽  
Author(s):  
Hongqiang Chen ◽  
Jeffrey W. Kysar ◽  
Y. Lawrence Yao
Keyword(s):  
Plastic Deformation ◽  
Single Crystal ◽  
Crystal Lattice ◽  
Electron Backscatter Diffraction ◽  
Fem Analysis ◽  
Copper Sample ◽  
Laser Shock Peening ◽  
Lattice Rotation ◽  
Laser Shock ◽  
Shock Peening

Electron backscatter diffraction (EBSD) is used to investigate crystal lattice rotation caused by plastic deformation during high-strain rate laser shock peening in single crystal aluminum and copper sample on 110¯ and (001) surfaces. New experimental methodologies are employed which enable measurement of the in-plane lattice rotation under approximate plane-strain conditions. Crystal lattice rotation on and below the microscale laser shock peened sample surface was measured and compared with the simulation result obtained from FEM analysis, which account for single crystal plasticity. The lattice rotation measurements directly complement measurements of residual strain/stress with X-ray micro-diffraction using synchrotron light source and it also gives an indication of the extent of the plastic deformation induced by the microscale laser shock peening.

Texture Evolution during Diffusional Heat Treatment from Roll-Bonded Ti/Ni Laminates to TiNi Shape Memory Alloy Sheets

2007 ◽  
Vol 539-543 ◽  
pp. 3442-3447 ◽  
Author(s):  
Hirofumi Inoue ◽  
K. Asao ◽  
Masaaki Ishio ◽  
Takayuki Takasugi
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Early Stage ◽  
Texture Evolution ◽  
Reactive Diffusion ◽  
Thin Sheets ◽  
Orientation Relationships ◽  
Nickel Metal ◽  
Recoverable Strain

TiNi shape memory alloy thin sheets were produced from titanium and nickel metal sheets by a new processing consisting of repetitive roll-bonding and diffusional heat treatment. TiNi sheets after heat treatment at a relatively low temperature for a long time exhibited fairly isotropic and high shape-recoverable strain, because a near {111} B2-phase texture such as {223}<110> and {332}<113> was developed through reactive diffusion during heat treatment. In the early stage of reactive diffusion, intermetallic layers of Ti2Ni, TiNi and Ni3Ti were formed at once at the Ti/Ni interfaces of the roll-bonded laminate and then growth of a TiNi phase took place with the progress of interdiffusion. Texture of the final TiNi thin sheets, therefore, is derived from that of TiNi layers generated at the Ti/Ni interfaces, which is considered to have inherited rolling textures of Ni and Ti layers in the Ti/Ni laminate prior to reactive diffusion under orientation relationships on close-packed plane and direction between parent and product phases.

Periodic crystal lattice rotation in microband groups in a bcc metal

2007 ◽  
Vol 57 (8) ◽  
pp. 775-778 ◽  
Author(s):  
Dorothée Dorner ◽  
Yoshitaka Adachi ◽  
Kaneaki Tsuzaki
Keyword(s):  
Crystal Lattice ◽  
Lattice Rotation ◽  
Bcc Metal ◽  
Periodic Crystal

The Fully Plastic, Plane-Strain Tension of a Notched Bar

1968 ◽  
Vol 35 (1) ◽  
pp. 111-116 ◽  
Author(s):  
J. E. Neimark
Keyword(s):  
Shear Strain ◽  
Strain Hardening ◽  
Plane Strain ◽  
Plastic Material ◽  
Extremum Principle ◽  
Displacement Distribution ◽  
Plane Strain Tension

Hill’s extremum principle for a strain-hardening plastic material is applied to determine the displacement distribution and the strains at the center and at the roots of rounded V-grooves in a bar in tension. This analysis is used to present the shear strain at fracture as a function of triaxial tension for 7075-T6 aluminum, as compared to the more usual tension and torsion tests.

Study of Microstructure and Texture Evolution Using In-Situ EBSD Investigations and SE Imaging in SEM

2006 ◽  
Vol 519-521 ◽  
pp. 809-814 ◽  
Author(s):  
Hans Bjerkaas ◽  
Snorre Kjørstad Fjeldbo ◽  
Hans Jørgen Roven ◽  
Jarle Hjelen ◽  
Rémi Chiron ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Initial Orientation ◽  
Lattice Rotation ◽  
Complex Nature ◽  
Texture Gradient ◽  
Slip Activity ◽  
Crystallographic Slip ◽  
Simple Tension ◽  
Grain Orientations

The crystallographic slip activity in several grains deformed by simple tension is determined by use of in-situ deformation in combination with Electron Back Scattering Diffraction (EBSD)-investigations and Secondary Electron (SE) imaging. This technique is also used to determine grain lattice rotation paths of grains with different initial orientation, providing information on basic deformation mechanisms of grains present in texture gradients. Both slip activity and grain lattice rotation paths depend on the initial orientation and are influenced by the neighbouring grain orientations. This indicates that predictions of the forming behaviour of extruded profiles with a strong through thickness texture gradient relate to a very complex nature.

A Parametric Study on Interlaminar Shear Strains in Cord-Rubber Composites

1984 ◽  
Vol 57 (1) ◽  
pp. 168-183 ◽  
Author(s):  
J. DeEskinazi ◽  
R. J. Cembrola
Keyword(s):  
Shear Strain ◽  
Relative Motion ◽  
Strong Influence ◽  
Design Parameters ◽  
Cross Sectional ◽  
Design Variables ◽  
Study Results ◽  
Shear Strains ◽  
Interlaminar Shear ◽  
Belt Width

Abstract The effect of different design variables used in the construction of tire belts on the interply shear phenomenon was studied using a simple, belted cylinder structure. Only balanced belt constructions were considered. The finite element method was used in the analysis of the belted structure. Predicted results were verified by performing experiments with selected combinations of the design parameters studied. Predicted and experimental results indicate the presence of interply shear strains in the cross-sectional plane of the belts; however, due to difficulties involved in measuring these strains experimentally, they have not been treated in this study. Results for shear strains in the circumferential planes only have been presented. Results for the interply shear strains at the belt edge indicate that the belt cord angle has a very strong influence on the interply shear phenomenon. It was shown that the shape of the curve depicting the relationship between cord angle and interply shear strains is influenced by other design variables of the belt as well as properties of adjacent plies, such as the bladder used to simulate a radial tire carcass ply. Interply shear strains decrease with increasing thickness between the plies and modulus of the interply rubber. In the case of a stiffer rubber, the reduction in shear strain is entirely due to a reduction in the relative motion between the belts. However, in the case of an increased interply thickness, which is accompanied by an increase in relative motion between the belts, the reduction in shear is the result of the relative motion being distributed over a larger thickness. Increasing the belt cord modulus results in an increase in interply shear strains for relatively low values of the modulus. However, beyond a certain value, approximately the modulus of fiberglass cords, increasing the cord modulus does not significantly affect interply shear strains. The shear strain-belt width relationship is strongly influenced by the cord angle used in the belts. Depending on the value of the latter, the shear strain can be a decreasing function of belt width or remain relatively constant as belt width is varied. The degree of localization of the interply shear phenomenon at the belt edge was also studied. All of the variables considered in this study, with the exception of the cord modulus, seem to affect the distribution of the shear strain along the width of the belt to varying extents. The belt width seems to have a strong influence, with wider belts resulting in significant shear strains confined to the vicinity of the belt edge.

scholarly journals Crystallographic preferred orientations of ice deformed in direct-shear experiments at low temperatures

2018 ◽  
Author(s):  
Chao Qi ◽  
David J. Prior ◽  
Lisa Craw ◽  
Sheng Fan ◽  
Maria-Gema Llorens ◽  
...  
Keyword(s):  
Shear Strain ◽  
Electron Backscatter Diffraction ◽  
Numerical Models ◽  
Boundary Migration ◽  
Shear Plane ◽  
Equivalent Strain ◽  
Lattice Rotation ◽  
Dislocation Creep ◽  
Shear Direction ◽  
Primary Cluster

Abstract. We sheared synthetic polycrystalline ice at temperatures of −5, −20 and −30 °C, to different shear strains, up to γ = 2.6 (equivalent strain of 1.5). Cryo-electron backscatter diffraction (EBSD) shows that basal intra-crystalline slip planes become preferentially oriented parallel to the shear plane, in all experiments. This is visualized as a primary cluster of crystal c-axes (the c-axis is perpendicular to the basal plane) perpendicular to the shear plane. In all except the two highest-strain experiments at −30 °C, a secondary cluster of c-axes is observed, at an angle to the primary cluster. With increasing strain, the primary c-axis cluster strengthens. With increasing temperature, both clusters strengthen. In the −5 °C experiments, the angle between the two clusters reduces with increasing strain. The c-axis clusters are elongated perpendicular to the shear direction. This elongation increases with increasing shear strain and with decreasing temperature. Highly curved grain boundaries are more prevalent in samples sheared at higher temperatures. At each temperature, the proportion of and irregularity of curved boundaries decreases with increasing shear strain. Subgrains are observed in all samples. Recrystallized grains and subgrains are similar in size and are both smaller than the original grains. Microstructural interpretations and comparisons of the data from experimentally sheared samples with numerical models suggest that the observed crystallographic orientation patterns result from a balance of the rates of lattice rotation (during dislocation creep) and growth of grains by strain-induced grain boundary migration (GBM). GBM is faster at higher temperatures and becomes less important as shear strain increases. These observations and interpretations provide a hypothesis to be tested in further experiments and using numerical models, with the ultimate goal of aiding the interpretation of crystallographic preferred orientations in naturally deformed ice.

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