scholarly journals Effect of Discontinuous Yielding on the Strain Hardening Behavior of Fine-Grained Twinning-Induced Plasticity Steel

2021 ◽  
Vol 8 ◽  
Author(s):  
Singon Kang ◽  
Sujin Jeong ◽  
Yeon-Sang Ahn
Keyword(s):  
Strain Hardening ◽  
Tensile Deformation ◽  
Early Stage ◽  
Image Correlation ◽  
Localized Deformation ◽  
Fine Grained ◽  
Cooling Conditions ◽  
Strain Hardening Behavior ◽  
Strain Hardening Rate

The yielding of a high Mn twinning-induced plasticity steel was examined in three fine-grained specimens recrystallized at 700°C for 5 min with different cooling conditions. While the stress-strain curves of furnace-cooled and air-cooled specimens exhibit a stress drop at yielding, the drop was not observed in the water-quenched specimen. A simple analysis of the displacement data indicates the occurrence of localized deformation at the beginning of the plastic deformation in the three tensile specimens with different cooling conditions. The localized deformation of all three specimens was confirmed as Lüders strain by digital image correlation (DIC) analysis. Based on this observation, the role of yielding behavior on the strain hardening rate evolution at an early stage of the tensile deformation was discussed.

A full-range stress-strain model for metallic materials depicting non-linear strain-hardening behavior

2020 ◽  
pp. 030932472095779
Author(s):  
Digendranath Swain ◽  
S Karthigai Selvan ◽  
Binu P Thomas ◽  
Ahmedul K Asraff ◽  
Jeby Philip
Keyword(s):  
Constitutive Model ◽  
Strain Hardening ◽  
Image Correlation ◽  
Linear Strain ◽  
Stress Strain ◽  
Material Parameters ◽  
Hardening Behavior ◽  
Non Linear ◽  
Strain Hardening Behavior ◽  
Strain Model

Ramberg-Osgood (R-O) type stress-strain models are commonly employed during elasto-plastic analysis of metals. Recently, 2-stage and 3-stage R-O variant models have been proposed to replicate stress-strain behavior under large plastic deformation. The complexity of these models increases with the addition of each stage. Moreover, these models have considered deformation till necking only. In this paper, a simplistic multi-stage constitutive model is proposed to capture the strain-hardening non-linearity shown by metals including its post necking behavior. The constitutive parameters of the proposed stress-strain model can be determined using only elastic modulus and yield strength. 3-D digital image correlation was used as an experimental tool for measuring full-field strains on the specimens, which were subsequently utilized to obtain the material parameters. Our constitutive model is demonstrated with an aerospace-grade stainless steel AISI 321 wherein deformation response averaged over the gauge length (GL) and at a local necking zone are compared. The resulting averaged and local material parameters obtained from the proposed model provide interesting insights into the pre and post necking deformation behavior. Our constitutive model would be useful for characterizing highly ductile metals which may or may not depict non-linear strain hardening behavior including their post necking deformations.

Digital image correlation shows localized deformation bands in inelastic loading of fibrolamellar bone

2009 ◽  
Vol 24 (2) ◽  
pp. 421-429 ◽  
Author(s):  
Gunthard Benecke ◽  
Michael Kerschnitzki ◽  
Peter Fratzl ◽  
Himadri S. Gupta
Keyword(s):  
Plastic Strain ◽  
Tensile Deformation ◽  
Image Correlation ◽  
Correlation Technique ◽  
Length Scale ◽  
Strain Rates ◽  
Deformation Bands ◽  
Localized Deformation ◽  
High Deformation ◽  
Multiple Regions

Irreversible or plastic deformation in bone is associated with both permanent plastic strain as well as localized microdamage. Whereas mechanisms at the molecular and mesoscopic level have been proposed to explain aspects of irreversible deformation, a quantitative correlation of mechanical yielding, microstructural deformation, and macroscopic plastic strain does not exist. To address this issue, we developed and applied a two-dimensional image correlation technique to the tensile deformation of bovine fibrolamellar bone, to determine the spatial distribution of strain fields at the length scale of 10 μm to 1 mm in bone during irreversible tensile deformation. We find that tensile deformation is relatively homogeneous in the elastic regime and starts at the yield point, showing regions of locally higher strain. Multiple regions of high deformation can exist at the same time over a length scale of 1 to 10 mm. Macroscopic fracture always occurs at one of the locally highly deformed regions, but the selection of which region cannot be predicted. Locally, strain rates can be enhanced by a factor of 3 to 10 over global strain rates in the highly deformed zones and are lower but always positive in all other regions. Light microscopic imaging shows the onset of structural “banding” in the regions of high deformation, which is most likely correlated to microstructural damage at the inter- and intrafibrillar level.

Plasticity Enhancement of MoSi2 at Elevated Temperatures Through the Addition of TiC

1992 ◽  
Vol 273 ◽  
Author(s):  
H. Chang ◽  
H. Kung ◽  
R. Gibala
Keyword(s):  
Brittle Fracture ◽  
Strain Hardening ◽  
Elevated Temperatures ◽  
Particulate Composites ◽  
Dislocation Generation ◽  
Hardening Behavior ◽  
Lower Strain ◽  
The Matrix ◽  
Strain Hardening Behavior ◽  
Strain Hardening Rate

ABSTRACTMonolithic MoSi2 and MoSi2-TiC particulate composites with 10 vol % and 15 vol % TiC were tested in compression between 950°C and 1200°C. The MoSi2-TiC composites can be deformed plastically at lower temperatures than MoSi2 can before brittle fracture occurs. The composites exhibit much lower strain hardening rates and attain zero strain hardening rate at much lower strains than monolithic MoSi2. The differences between the composites and monolithic MoSi2 in plasticity and in strain hardening behavior is attributed to efficient dislocation generation into the matrix from sources at the MoSi2-TiC interfaces.

Influence of Various Precipitate Phases on Tensile Properties of an Extruded Mg-Y-Nd Alloy

2014 ◽  
Vol 788 ◽  
pp. 17-22 ◽  
Author(s):  
Bo Song ◽  
Ren Long Xin ◽  
Gang Chen ◽  
Ke Zeng ◽  
Guang Jie Huang ◽  
...  
Keyword(s):  
Yield Strength ◽  
Strain Hardening ◽  
Tensile Properties ◽  
Precipitation Hardening ◽  
High Strength ◽  
Age Hardening ◽  
Hardening Behavior ◽  
Initial Stage ◽  
Strain Hardening Behavior ◽  
Strain Hardening Rate

The high strength of Mg-Y-Nd alloy has been achieved primarily by precipitation hardening. Therefore, it is important to investigate the influence of various precipitate phases on the tensile properties of Mg-Y-Nd alloys. In this study, an extruded Mg-Y-Nd alloy was aged at various temperatures to examine the hardening behaviors. The results showed that the as-extruded alloy exhibited remarkable age hardening response at 210°C due to the precipitation of β’, and slight hardening response at 150°C and 280°C due to the precipitation of β’’ and β, respectively. Furthermore, different precipitates exerted different effects on the tensile properties. In comparison with the as-extruded alloy, the yield strength of the alloys aged at 210 °C and 150 °C was increased by 21 MPa and 8 MPa, respectively, whereas the yield strength of the alloy aged at 280°C was decreased by 30 MPa. The elongation of the alloy aged at 210°C and 150°C was also largely reduced by 3.4% and 2.9%, respectively, while the elongation of the alloy aged at 280°C was only slightly reduced (6.3%). Moreover, compared with the as-extruded alloy, the alloy aged at 210°C and 150°C exhibited lower hardening capacity and higher strain hardening rate at the initial stage, but the strain hardening rate decreased more quickly with the increasing stress. The alloy aged at 280°C exhibited similar strain hardening behavior with the as-extruded alloy. The results in this study provide guidelines for determining the heat treatment parameters for the Mg-Y-Nd alloys to improve their tensile properties.

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