Understanding the Rheological Transitions in Semi-Solid Alloys by a Combined In Situ Imaging and Granular Micromechanics Modeling Approach

2022 ◽  
Vol 327 ◽  
pp. 127-132
Author(s):  
Te Cheng Su ◽  
Catherine O'Sullivan ◽  
Hideyuki Yasuda ◽  
Christopher M. Gourlay
Keyword(s):  
Shear Rate ◽  
Solid Fraction ◽  
Discrete Element ◽  
Quantitative Agreement ◽  
Micromechanical Modeling ◽  
Two Phase ◽  
Shear Cracking ◽  
Semi Solid ◽  
Boltzmann Method

To gain better understanding of rheological transitions from suspension flow to granular deformation and shear cracking, this research conducted shear-deformation on globular semi-solid Al-Cu alloys to study the rheological behavior of semi-solid as a function of solid fraction (38% - 85%) and shear rate (10-4 – 10-1 s-1) under real-time synchrotron radiography observation. By analyzing 17 X-ray imaging datasets, we define three rheological transitions: (i) the critical solid fraction from a suspension to a loosely percolating assembly; (ii) from the net contraction of a loose assembly to the net dilation of a densely packed assembly, and (iii) to shear cracking at high solid fraction and shear rate. Inspired by in-situ observations of semi-solid deformation showing a disordered assembly of percolating crystals in partially-cohesive contact with liquid flow, we reproduced a two-phase sample using the coupled lattice Boltzmann method-discrete element method (LBM-DEM) simulation approach for granular micromechanical modeling. In DEM, each globular Al grain is represented by a discrete element, and the flow of interstitial liquid is solved by LBM. The LBM-DEM simulations show quantitative agreement of semi-solid strain localization with the experiments and are used to explore the components involved in the shear rate dependence of the transitions, and the role of liquid pressure on the initiation of shear cracking.

Modeling of Semi-Solid A356 Alloy under Upsetting Process

2006 ◽  
Vol 116-117 ◽  
pp. 622-625
Author(s):  
M. Shakiba ◽  
Hossein Aashuri
Keyword(s):  
Solid Fraction ◽  
Yield Criterion ◽  
Flow Behavior ◽  
A356 Alloy ◽  
Two Phase ◽  
Thermomechanical Process ◽  
Modeling Process ◽  
High Solid Fraction ◽  
Flow Through ◽  
Semi Solid

The flow behavior of a semi-solid A356 alloy at high solid fraction was studied. The mushy zone was considered as an effective two-phase, so that the solid continuum can be compressible porous media, and the liquid phase interaction with the solid skeleton was of Darcy type. The semi-solid flow through the upsetting test was modeled in ABAQUS finite element method software. The Gurson yield criterion has been developed for the modeling process of the flow behavior of solid porous medium. Specimens were globulized by a thermomechanical process and then were tested for various percentages of upsetting. The distribution of solid fraction along the radius of the specimens at different height reduction showed a good correlation with model prediction.

scholarly journals Rheology-based method for calculating polymer inaccessible pore volume in core flooding experiments

2019 ◽  
Vol 89 ◽  
pp. 04001 ◽  
Author(s):  
V. H. S. Ferreira ◽  
R. B. Z. L. Moreno
Keyword(s):  
Shear Rate ◽  
Pore Volume ◽  
Single Phase ◽  
Relative Difference ◽  
Core Flooding ◽  
Two Phase ◽  
Shear Rates ◽  
The Core ◽  
Inaccessible Pore Volume

Polymer flooding is an enhanced oil recovery (EOR) method that reduces the mobility ratio between the displaced oil and the displacing injected water. The flow of polymer solutions through porous media is subject to some process-specific phenomena, such as the inaccessible pore volume (IAPV). Due to IAPV, polymer molecules move faster through the porous medium than smaller ones. Thus the IAPV value needs to be accounted for in experiments and field projects. Recent reports found that polymer in-situ rheology correlates with the IAPV. The objective of this paper is to develop a method for estimating IAPV based on the in-situ rheology of polymers. The methodology proposed here can be used in both single- and two-phase experiments. The technique requires measurement of polymer resistance factor (RF) and residual resistance factor (RRF) at steady state conditions. Core permeability, porosity, and residual oil saturation, as well as water and polymer bulk viscosities, also need to be taken into account. Correlations for polymer in-situ viscosity and shear rate are solved simultaneously, to wield an estimative for the IAPV. Aiming at to prove the method, we report 16 core-flooding experiments, eight single- and eight two-phase experiments. We used a flexible polymer and sandstone cores. All the tests were run using similar rock samples. In the single-phase experiments, we compare the alternative method with the classic tracer method to estimate IAPV. The results show an average relative difference of 11.5% between the methods. The two-phase results display, on average, an 18% relative difference to the IAPV measured in the single-phase experiments. The difference between single- and two-phase results can be an effect of the higher shear rates experienced in the two-phase floodings since, in these cases, the aqueous phase shear rate is also dependent on the phase saturation. Additionally, temperature, core length, pore pressure, and iron presence on the core did not show any influence on the IAPV for our two-phase experiments. The method proposed in this paper is limited by the accuracy of the pressure drop measurements across the core. For flexible polymers, the method is valid only for low and mid shear rates, but, accoording to literature, for rigid polymers the method should be accurate for a broad range of shear rates. The method proposed here allows the measurement of polymer IAPV on two- and single- phase core-flooding experiments when a tracer is not used.

The Rheological Behavior of HS6-5-2 Tool Steel for Non-Isothermal Processing

2012 ◽  
Vol 192-193 ◽  
pp. 317-322
Author(s):  
Farzad Hosseini Yekta ◽  
S.A. Sadough ◽  
Vahid Pouyafar ◽  
Amin Jabbari
Keyword(s):  
Shear Rate ◽  
Cooling Rate ◽  
Tool Steel ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Liquid Fraction ◽  
Outer Cylinder ◽  
Processing Temperature ◽  
Applied Torque ◽  
Semi Solid

The rheological behavior of semi-solid tool steel is investigated using a conventional rheometer under cooling rate and shear rate. The processing of steels in semi-solid state is still at development stage due to the high processing temperature involved. The candidate grades of steel for thixoforming are high speed, high carbon, stainless steel and ductile iron. TheHS6-5-2 tool steel has a wide semi-solid range of over 200 C and the required spheroidal microstructure achieved by partial re-melting from as supplied state without any mechanical agitation, indicated the potential of this grade to be investigated in semi-solid processing. For non-isothermal processing an increase of solid fraction related to solidification due to thermal exchanges is observed. In the first series of experiment after melting the feed stock in an alumina cup, the alloy is sheared continuously by a rotating rod with a constant shear rate under three different cooling rates to the 55% corresponding liquid fraction. In the second series of experiment three different shear rates were applied under a constant cooling rate. The apparent viscosity of the slurry as a function of cooling rate and solid fraction is calculated from the applied torque to the outer cylinder. The results show that the slurry viscosity decreases with increasing shear rate and increases with increasing cooling rate and solid fraction. Additionally for a given solid fraction, shear thinning behavior is observed.

In Situ Observation of Deformation in Semi-solid Fe-C Alloys at High Shear Rate

2014 ◽  
Vol 45 (12) ◽  
pp. 5613-5623 ◽  
Author(s):  
Tomoya Nagira ◽  
Shugo Morita ◽  
Hiroyoshi Yokota ◽  
Hideyuki Yasuda ◽  
Christopher M. Gourlay ◽  
...  
Keyword(s):  
Shear Rate ◽  
High Shear Rate ◽  
In Situ Observation ◽  
High Shear ◽  
Semi Solid

Ti-Zr-V-Cu-Be BMGMCs Processed by Semi-Solid Processing

2019 ◽  
Vol 285 ◽  
pp. 111-114
Author(s):  
Hong Min Guo ◽  
Le Rong Bai ◽  
Bin Liu ◽  
Xiang Jie Yang
Keyword(s):  
Glass Matrix ◽  
Isothermal Holding ◽  
Solidification Process ◽  
Time Interval ◽  
Compression Tests ◽  
Two Phase ◽  
Semi Solid ◽  
Glass Matrix Composites ◽  
Copper Mould

Compared with monolithic bulk-metallic glasses at room temperature, in-situ two-phase bulk metallic glass matrix composites (BMGMCs) exhibit improved toughness. However, most of in-situ BMGMCs are developed through extremely rapid cooling, during which the solidification process cannot be controlled effectively. As a consequence, the microstructures of in situ two-phase composites, even with the same composition, vary from one to another, highly depend on the cooling rate. In the present investigation, the Ti-Zr-V-Cu-Be BMGMCs was prepared by using copper mould suction process, and the evolution of microstructures at semi-solid stage was investigated. The results indicated that microstructures of billets, produced by copper mould suction and water quenching after isothermal holding at semi-solid stage, mainly contained β-Ti phase and glass matrix. Isothermal holding temperature and time interval determined the final morphology of β-Ti phase. Compression tests showed that semi-solid processing could further improve ductility of BMGMCs effectively.

scholarly journals A non-destructive method for measuring the salinity and solid fraction of growing sea ice in situ

2005 ◽  
Vol 51 (172) ◽  
pp. 159-166 ◽  
Author(s):  
Dirk Notz ◽  
John S. Wettlaufer ◽  
M. Grae Worster
Keyword(s):  
Sea Ice ◽  
Solid Fraction ◽  
Ice Core ◽  
Ice Cores ◽  
The Arctic ◽  
Two Phase ◽  
Theoretical Predictions ◽  
Bulk Salinity ◽  
General Studies

AbstractWe describe an instrument developed to make in situ measurements of salinity and solid- fraction profiles in growing sea ice. The vertical resolution of the measurements is up to a few millimeters, with a temporal resolution of up to fractions of a second. The technique is based on impedance measurements between platinum wires around which sea ice grows. Data obtained using this instrument in laboratory experiments are in good agreement with theoretical predictions. In a field test in the Arctic, the bulk salinity of growing sea ice has been measured in situ throughout the whole depth of the ice layer. The data are compared with bulk salinities obtained from ice cores, and confirm the general understanding that the bulk salinity in ice-core studies is significantly underestimated in the lower parts of the cores. The approach can also be used in other glaciological applications and for general studies of two-phase, two-component porous media.

In Situ Study of the Altering Globule Packing-Density during Semisolid Alloy Deformation

2012 ◽  
Vol 192-193 ◽  
pp. 185-190
Author(s):  
C.M. Gourlay ◽  
T. Nagira ◽  
Kentaro Uesugi ◽  
Hideyuki Yasuda
Keyword(s):  
Solid Fraction ◽  
Packing Density ◽  
Solid Deformation ◽  
Synchrotron Radiography ◽  
Semisolid Alloy ◽  
Local Compaction ◽  
Semi Solid ◽  
The Individual ◽  
Water Saturated

Synchrotron radiography experiments are overviewed that directly image semi-solid deformation at the globule-scale. Globular Al-15Cu at 50-60% solid was deformed in direct-shear at 10-2 s-1. Deformation is shown to occur by globule rearrangement without discernible deformation of the individual globules. Globules were found to translate and rotate as quasi-discrete bodies in response to forces acting at globule-globule contacts, similar to liquid-saturated granular materials such as water-saturated sand. Rearrangement caused the globule packing-density (the solid fraction) to adjust by local compaction and local dilation of the globule assembly, and deformation is highly inhomogeneous. During shear, there was a net dilation and strain began to localize into a shear band of decreased solid fraction by the end of the experiments.

Rheological Behavior and Fluidity of Semi-Solid SiCp/A357 Composites with Different SiC Addition Levels

2016 ◽  
Vol 256 ◽  
pp. 126-132 ◽  
Author(s):  
Zhen Lin Zhang ◽  
Zhi Feng Zhang ◽  
Jun Xu ◽  
Wei Min Mao
Keyword(s):  
Shear Rate ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Stir Casting ◽  
Sic Particles ◽  
Semi Solid ◽  
Test Casting ◽  
Good Agreement

The apparent viscosities of the semi-solid SiCp/A357 composites with 0vol.%, 10vol.% and 20vol.% SiC particles manufactured by stir casting were investigated using a Couette type viscometer, and the composite fluidity was examined with a test casting. The results showed that, the viscosities of the semi-solid SiCp/A357 composites decreased with an increase in shear rate, but increased with the increasing of solid fraction, and apparent viscosity of 10vol.% SiCp/A357 composite was the lower than that of 20vol.% SiCp/A357 composite at the same solid fraction; and the composite fluidity results were in a good agreement with the viscosity ones.

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