scholarly journals A physically based constitutive model for dynamic strain aging in Inconel 718 alloy at a wide range of temperatures and strain rates

2019 ◽  
Vol 231 (1) ◽  
pp. 19-34 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Yooseob Song
Keyword(s):  
Constitutive Model ◽  
Dynamic Strain Aging ◽  
Inconel 718 ◽  
Strain Aging ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Inconel 718 Alloy ◽  
Wide Range ◽  
Physically Based

scholarly journals Constitutive Models for Dynamic Strain Aging in Metals: Strain Rate and Temperature Dependences on the Flow Stress

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1794 ◽  
Author(s):  
Yooseob Song ◽  
Daniel Garcia-Gonzalez ◽  
Alexis Rusinek
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Dynamic Loading ◽  
Dynamic Strain Aging ◽  
Static Loading ◽  
Strain Aging ◽  
Mechanical Response ◽  
Dynamic Strain ◽  
Proposed Model ◽  
Wide Range

A new constitutive model for Q235B structural steel is proposed, incorporating the effect of dynamic strain aging. Dynamic strain aging hugely affects the microstructural behavior of metallic compounds, in turn leading to significant alterations in their macroscopic mechanical response. Therefore, a constitutive model must incorporate the effect of dynamic strain aging to accurately predict thermo-mechanical deformation processes. The proposed model assumes the overall response of the material as a combination of three contributions: athermal, thermally activated, and dynamic strain aging stress components. The dynamic strain aging is approached by two alternative mathematical expressions: (i) model I: rate-independent model; (ii) model II: rate-dependent model. The proposed model is finally used to study the mechanical response of Q235B steel for a wide range of loading conditions, from quasi-static loading ( ε ˙ = 0.001   s − 1 and ε ˙ = 0.02   s − 1 ) to dynamic loading ( ε ˙ = 800   s − 1 and ε ˙ = 7000   s − 1 ), and across a broad range of temperatures ( 93   K − 1173   K ). The results from this work highlight the importance of considering strain-rate dependences (model II) to provide reliable predictions under dynamic loading scenarios. In this regard, rate-independent approaches (model I) are rather limited to quasi-static loading.

THERMOMECHANICAL RESPONSE OF THE ROTARY FORGED WHA OVER A WIDE RANGE OF STRAIN RATES AND TEMPERATURES

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5431-5437 ◽  
Author(s):  
W. G. GUO ◽  
C. QU ◽  
F. L. LIU
Keyword(s):  
Strain Rate ◽  
Dislocation Motion ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Thermomechanical Response ◽  
Tension Tests ◽  
Wide Range ◽  
Physically Based ◽  
Split Hopkinson ◽  
Modeling Prediction

This paper is to understand and model the thermomechanical response of the rotary forged WHA, uniaxial compression and tension tests are performed on cylindrical samples, using a material testing machines and the split Hopkinson bar technique. True strains exceeding 40% are achieved in these tests over the range of strain rates from 0.001/s to about 7,000/s, and at initial temperatures from 77K to 1,073K. The results show: 1) the WHA displays a pronounced changing orientation due to mechanical processing, that is, the material is inhomogeneous along the section; 2) the dynamic strain aging occurs at temperatures over 700K and in a strain rate of 10-3 1/s; 3) failure strains decrease with increasing strain rate under uniaxial tension, it is about 1.2% at a strain rate of 1,000 1/s; and 4) flow stress of WHA strongly depends on temperatures and strain rates. Finally, based on the mechanism of dislocation motion, the parameters of a physically-based model are estimated by the experimental results. A good agreement between the modeling prediction and experiments was obtained.

Effects of Strain Rate on Dynamic Strain Aging of SA508-III Steel

2014 ◽  
Vol 788 ◽  
pp. 334-339 ◽  
Author(s):  
Dan Yuan ◽  
Lei Wang ◽  
Yang Liu ◽  
Xiu Song ◽  
Jia Hua Liu
Keyword(s):  
Strain Rate ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Cell Structure ◽  
Tensile Tests ◽  
Dislocation Cell ◽  
Strain Rate Range ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Reduction Of Area

The dynamic strain aging (DSA) behavior of SA508-III steel was evaluated through tensile tests with different strain rates from 10-4 to 10-1s-1 at 350°C. The OM, SEM and TEM were carried out to observe the microstructures and fracture morphologies of the steel. The results show that the serrated flows appear in the stress-strain curves when the strain rate is between 10-3~10-2s-1, indicating that DSA occurs. Under the strain rate range, the tensile strength increases and the elongation and the reduction of area decrease. However, the fracture surface of the steel after tensile tests is still ductile. DSA in SA508-III steel at the strain rates from10-3 to 10-2s-1 is mainly caused by the interaction between the internal solute atoms and dislocations, which leads to the dislocations multiplication and the formation of sub-grain boundaries and dislocation cell structure.

Constitutive model for metals with dynamic strain aging

2019 ◽  
Vol 129 ◽  
pp. 352-360 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Yooseob Song ◽  
Alexis Rusinek
Keyword(s):  
Constitutive Model ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Dynamic Strain

Dynamic Strain Aging and the Charpy Specimen Behavior of Annealed 4340 Steel

1968 ◽  
Vol 90 (1) ◽  
pp. 13-20 ◽  
Author(s):  
W. R. Clough ◽  
L. A. Jackman ◽  
Y. G. Andreev
Keyword(s):  
Dynamic Strain Aging ◽  
Cleavage Fracture ◽  
Strain Aging ◽  
Room Temperature ◽  
Carbon Steels ◽  
Dynamic Strain ◽  
Charpy Specimen ◽  
Strain Rates ◽  
Aging Effects ◽  
Lower Carbon

V-notch Charpy bars were ruptured at seven deflection rates at test temperatures from the ambient through the blue-brittle range, while unnotched tensile specimens were equivalently tested at four strain rates. Objectives were to interpret and relate dynamic strain aging manifestations of annealed 4340 shown by the two types of tests. Comparisons are made with elastic-plastic formulations and experimental results for initial yielding and fracture of notched bars at or near room temperature. Quasi-cleavage fracture was observed in excess of 500 deg F. Dynamic strain aging effects are compared with those found with less alloyed lower carbon steels. Arrhenius type relations are developed and discussed, and from these other interrelations are derived, and mechanisms are discussed.

Dynamic Strain Aging during the Plastic Flow of Metals

2007 ◽  
Vol 340-341 ◽  
pp. 823-828 ◽  
Author(s):  
Wei Guo Guo
Keyword(s):  
Experimental Data ◽  
Flow Stress ◽  
Plastic Flow ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Testing Machine ◽  
Strain Curve ◽  
Dynamic Strain ◽  
Polycrystalline Materials ◽  
Strain Rates

In the present paper, in order to better understand the third type “dynamic strain aging” occurring during the plastic flow of metals, the uniaxial compressive experimental data ever obtained in University of California, San Diego using an Instron servo-hydraulic testing machine and the Hopkinson technique are systematically analysed. These experimental data cover the plastic flow stress of several fcc, hcp, bcc polycrystalline materials and several alloys at a broad range of temperatures (77K – 1,100K) and strain rates (0.001/s – 10,000/s). In analysis, the appearing region of the “dynamic strain aging ” under different temperatures and strain rates are respectively plotted by the curves of stress vs temperature, and stress vs strain for fcc, hcp and bcc metals. The results show that: (1) this third type “dynamic strain aging ” occurs in all hcp, bcc and fcc polycrystalline or alloy materials, and there are different profiles of stress-strain curve; (2) the “dynamic strain aging ”occurs in a matching coincidence of the temperature and strain rate, its temperature region will shift to higher region with increasing strain rates; (3) bcc materials do not have an initial pre-straining strain as the onset of work-hardness rate change for the “dynamic strain aging ”; and (4) based on the explanations of dynamic strain aging with serration curves (Portevin-Lechatelier effect) and other explaining mechanisms of references, The mechanism of third DSA is thought as the rapid/continuous formation of the solute atmospheres at the mobile dislocation core by the pipe diffusion along vast collective forest dislocations to result in a continuous rise curve of flow stress. Finally, several conclusions are also presented.

scholarly journals Effects of microstructure on the dynamic strain aging of ferriticpearlitic steels at high strain rates

2018 ◽  
Vol 183 ◽  
pp. 03009
Author(s):  
Ahmad Mardoukhi ◽  
Jari Rämö ◽  
Taina Vuoristo ◽  
Amandine Roth ◽  
Mikko Hokka ◽  
...  
Keyword(s):  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Aging Effect ◽  
Grain Structure ◽  
Dynamic Strain ◽  
Maximum Effect ◽  
Strain Rates ◽  
Hopkinson Pressure Bar

This paper presents an experimental study of the effects of dynamic strain aging on the mechanical behavior of selected high carbon and chromium-manganese steels in dynamic loading condition. In ferritic-pearlitic steels, the dynamic strain aging is typically caused by carbon, nitrogen, and possibly some other small solute atoms. Therefore, the thermomechanical treatments affect strongly how strong the dynamic strain aging effect is and at what temperature and strain rate regions the maximum effect is observed. In this work, we present results of the high temperature dynamic compression tests carried out for two different ferritic-pearlitic steels, 16MnCr5 and C60, that were heat treated to produce different microstructure variants of these standard alloys. The microstructures were analyzed using electron microscopy, and the materials were tested with the Split Hopkinson Pressure Bar device at three different strain rates at temperatures ranging from room temperature up to 680 °C to study the effect of the heat treatments and the resulting microstructures on the dynamic behavior of the steels and the dynamic strain aging effect. The results indicate that for both steels, a coarse grain structure has the strongest dynamic strain aging sensitivity at small plastic strains. However, at higher strains, all microstructures show similar strain aging sensitivities.

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