Deformation Twinning Behavior in High Ni-Austenitic Materials

2018 ◽  
Vol 941 ◽  
pp. 1591-1596 ◽  
Author(s):  
Joakim Nordström ◽  
Raveendra Siriki ◽  
Johan Moverare ◽  
Guocai Chai
Keyword(s):  
Grain Orientation ◽  
Cryogenic Temperature ◽  
Strain Range ◽  
Deformation Twinning ◽  
Alloy 625 ◽  
Ni Alloys ◽  
Deformation Twins ◽  
Sanicro 28 ◽  
Schmid Factor ◽  
Strength And Ductility

Deformation twinning behaviors have been studied in high Ni alloys, Alloy 28 or Sanicro 28 and Alloy 625 at RT and at cryogenic temperature. The microstructures were evaluated using SEM-EBSD. Some constitutive approach has also been used in the discussion on the deformation twinning in high Ni-alloys. The results show that deformation twinning can occur in high Ni alloys depending on the chemical composition, strain range and stress conditions. TWIP can occur in the Ni based superalloy Alloy 625 at cryogenic temperature, which increases both strength and ductility. This is the first report of this phenomena for this alloy. Deformation twinning in high Ni alloys occurs heterogeneously in the material, depending on crystallographic parameters such as grain orientation and Schmid factor. Formation of deformation twins can lead to high texture in the material, which will contribute to the increase of strength. The mechanisms for the formation of deformation twins in high Ni alloys have been discussed.

The Origin of Deformation Twinning in Polycrystalline γ'Containing Nickel-Base Alloys

1971 ◽  
Vol 29 ◽  
pp. 114-115
Author(s):  
J. M. Oblak ◽  
D. S. Duvall
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Orientation ◽  
Tensile Axis ◽  
Deformation Twinning ◽  
Tensile Creep ◽  
Temperature Deformation ◽  
Single Slip ◽  
Schmid Factor ◽  
Nickel Base

As in certain other γ' containing nickel-base alloys, twinning is observed after the intermediate temperature deformation of polycrystalline IN-100, Figure 1. The presence of twinning is dependent upon grain orientation and is favored in grains oriented with an <011> pole near the tensile creep axis. (All foils were taken transverse to the tensile axis.) This is to be expected since <011> is near a single slip orientation of high Schmid factor for {111} <112> shear.Previously it had been suggested that the dislocations required for {111} <112>.shear and twinning were produced by interaction of 1/2 <110> dislocations. Yet, twinning is observed at the earliest stage of deformation in polycrystalline IN-100, Figure 2. Further examination demonstrated that the grain boundaries are sources for the initiation of twinning. A typical example is shown in Figure 3 where faulted configurations associated with twinning extend from the grain boundary into the γ' containing matrix.

Effects of Temperature and Strain Rate on Stress-Strain Relationship and Deformation Twinning in Fe-5%Si Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 910-915 ◽  
Author(s):  
Takashi Mizuguchi ◽  
Kento Ikeda ◽  
Naoki Karasawa ◽  
Yasuhiro Tanaka
Keyword(s):  
Strain Rate ◽  
Single Crystals ◽  
Grain Orientation ◽  
Tensile Tests ◽  
Total Elongation ◽  
Deformation Twinning ◽  
Strain Rates ◽  
Deformation Twins ◽  
Strain Relationship ◽  
Effects Of Temperature

The effects of temperature and strain rate on the stress–strain relationship and deformation twinning, during tensile tests, in polycrystalline Fe–5%Si alloy were studied. We performed tensile tests over a wide range of temperatures from 173 to 273 K, and strain rates ranging from 0.0001 to 0.1 /s, to clarify the relationship between total elongation and ratio of deformation twins, and the dependence of deformation twinning on grain orientation. All tensile specimens were fractured in a completely brittle manner. The total elongation decreased as the temperature decreased and the strain rate increased. The presence of deformation twins, in all fractured specimens, was confirmed by scanning electron microscope–electron backscattering diffraction analyses. The area fraction of the deformation twins increased as the total elongation decreased. However, a strong influence from the grain orientation on twinning activity was not observed for all temperatures and strain rates. A previous study on Fe–Si alloy single crystals showed that deformation twins form easily in <001>-oriented single crystals, but not in <111>-oriented single crystals. Our observations, on the dependence of deformation twinning on grain orientation in polycrystalline Fe–5%Si alloy, did not agree with those from single crystals. The present findings suggest that grain orientation does not play an important role in determining the occurrence of deformation twinning; not even in polycrystals. It is believed that the stress concentration, due to piled-up dislocations, during tensile deformation, cannot be relieved by the slip at low temperatures or high strain rates, and thus significantly affects deformation twinning.

scholarly journals Deformation twinning and the role of amino acids and magnesium in calcite hardness from molecular simulation

2015 ◽  
Vol 17 (31) ◽  
pp. 20178-20184 ◽  
Author(s):  
A. S. Côté ◽  
R. Darkins ◽  
D. M. Duffy
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Molecular Simulation ◽  
Elastic Properties ◽  
Deformation Twinning ◽  
Pure Crystal ◽  
Classical Molecular Dynamics ◽  
Deformation Twins

We employ classical molecular dynamics to calculate elastic properties and to model the nucleation and propagation of deformation twins in calcite, both as a pure crystal and with magnesium and aspartate inclusions.

Fatigue Properties of Superelastic Ti-Ni Filaments Used in Braided Cables for Bone Fixation

2008 ◽  
Vol 57 ◽  
pp. 235-240 ◽  
Author(s):  
Yannick Baril ◽  
Vladimir Brailovski ◽  
Patrick Terriault
Keyword(s):  
Fatigue Life ◽  
Strain Range ◽  
Fatigue Properties ◽  
Cyclic Testing ◽  
Testing Conditions ◽  
Bone Fixation ◽  
Ni Alloys ◽  
Strain Magnitude ◽  
The Impact ◽  
Mean Strain

Superelastic 0.1mm diameter Ti-Ni filaments are used to manufacture braided orthopedic cable for bone fixation. Biomechanical conditions for this application generally have a cyclic nature, and therefore it becomes important to evaluate the influence of the installation (mean) strain on the fatigue life of these filaments. Uniaxial tension cyclic testing of Ti-Ni filaments is performed in a water bath at 37°C with a 2Hz frequency of to 100 000 cycles. Strain-controlled testing conditions are as follows: alternating strain magnitude varies between 0.64 and 3.64% with mean strain range between 1.32 and 7.1%. Based on the premises that the minimum strain should be high enough to prevent any loss of tension in the tested specimen and that the maximum strain should not bring the specimen to failure during the first loading cycle, the total strain magnitude is encompassed between 0.68 and 8.94%. The results obtained provide a better understanding of the impact mean strain has on the fatigue life of superelastic Ti-Ni alloys.

Deformation twinning in Ni and F.C.C. Fe-Ni alloys

1967 ◽  
Vol 15 (137) ◽  
pp. 1051-1055 ◽  
Author(s):  
R. P. Reed
Keyword(s):  
Deformation Twinning ◽  
Ni Alloys

Grain Size in Mg Alloys: Recrystallization and Mechanical Consequences

2007 ◽  
Vol 558-559 ◽  
pp. 433-440 ◽  
Author(s):  
Matthew R. Barnett ◽  
Dale Atwell ◽  
Aiden G. Beer
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Mechanical Response ◽  
Deformation Twinning ◽  
Simultaneous Increase ◽  
The Impact ◽  
Strength And Ductility

The present paper examines the development of grain size during the recrystallization of magnesium alloys and the influence the grain size has on the mechanical response. In magnesium alloys grain refinement improves the strength-ductility balance. This simultaneous increase in both strength and ductility is ascribed to the impact the grain size has on deformation twinning. The mechanisms by which the grain size is established during hot working are shown to be conventional dynamic recrystallization followed by post-dynamic recrystallization. The role of alloying addition on both of these reactions is briefly considered.

The Brittle-to-Ductile Transition Behaviour in Fe-Al Single Crystalline Alloys

2011 ◽  
Vol 409 ◽  
pp. 243-248
Author(s):  
Keiki Maeno ◽  
Masaki Tanaka ◽  
Kenji Higashida ◽  
Masahiro Fujikura ◽  
Kohsaku Ushioda
Keyword(s):  
Brittle Fracture ◽  
Low Temperatures ◽  
Room Temperature ◽  
Tensile Tests ◽  
Initiation Site ◽  
Deformation Twinning ◽  
Brittle To Ductile Transition ◽  
Elastic Regime ◽  
Deformation Twins ◽  
Transition Behaviour

The morphology of deformation twinning, which influences a brittle fracture at low temperatures, was investigated in Fe-8mass%Al. Tensile tests were performed at 129K and room temperature. The specimen tested at room temperature showed yielding and kept deformed by usual slip while the specimen tested at 129K fractured in a brittle manner in an elastic regime with a number of straight markings due to deformation twinning. Detail analysis of those deformation twins suggests that the collision of deformation twinning is the initiation site of the brittle fracture.

Dependence of deformation twinning on grain orientation in a high manganese steel

2006 ◽  
Vol 55 (7) ◽  
pp. 629-631 ◽  
Author(s):  
P. Yang ◽  
Q. Xie ◽  
L. Meng ◽  
H. Ding ◽  
Z. Tang
Keyword(s):  
Grain Orientation ◽  
Deformation Twinning ◽  
Manganese Steel ◽  
High Manganese ◽  
High Manganese Steel
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