Deformation and Failure of Ultrafine-Grained Cu at Subambient Temperature

2017 ◽  
Vol 891 ◽  
pp. 249-253
Author(s):  
Alena Juríková ◽  
Kornel Csach ◽  
Jozef Miškuf ◽  
Mária Huráková ◽  
Elena D. Tabachnikova ◽  
...  
Keyword(s):  
Failure Process ◽  
Ductile Failure ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
High Plasticity ◽  
Pressing Method ◽  
Deformation And Failure ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Subambient Temperature

The ultrafine-grained copper was obtained by 12 passes of equal-channel angular pressing method. The uniaxial tensile tests at room temperature and the subambient temperature of 77 K show that the yield stress increases from the value of 128 MPa to the value of 138 MPa, respectively. In addition, the lowering the test temperature tends to the increase of the deformation before the failure. The fractographic analysis shows the transcrystalline ductile failure for all samples. Due to the high plasticity of nanostructured copper no influence of the nanoporosity on the failure process was observed.

Structuration of Refractory Metals Tantalum and Niobium Using Modified Equal Channel Angular Pressing Technique

2019 ◽  
Vol 799 ◽  
pp. 103-108 ◽  
Author(s):  
Lembit Kommel ◽  
Babak Shahreza Omranpour ◽  
Valdek Mikli
Keyword(s):  
Equal Channel Angular Pressing ◽  
Coarse Grained ◽  
Uniaxial Tensile ◽  
Modified Technique ◽  
Uniaxial Tensile Strength ◽  
Large Samples ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Von Mises ◽  
Ultrafine Grained Microstructure

In the present work, we use a modified Equal Channel Angular Pressing technique for structure and properties change of Tantalum and Niobium at room temperature. The main advantage of this modified technique is the possibility to produce relatively large samples with ultrafine-grained microstructure in all volume of the workpiece by reduced deformation load up to 25% via friction decrease, and also to prevent the punch fracture under high compression stress during pressing. The various microstructures and properties were produced in metals by using different von Mises strain levels up to ƐvM = 13.8. The changes in microstructure were studied by using SEM and TEM techniques. The change of mechanical properties was measured by using various tension and hardness testing setups. We can conclude that during processing the ultrafine-grained microstructure in as-cast Nb and Ta was formed. The uniaxial tensile strength, Vickers hardness, and plasticity of Nb and Ta significantly increased as compared to coarse-grained counterparts. We believe that the relatively large workpieces of pure bulk Ta and Nb metals with improved microstructure and exploitation properties are suitable materials for the modern industry.

Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe Plastic Deformation Route?

2012 ◽  
Vol 706-709 ◽  
pp. 1781-1786 ◽  
Author(s):  
You Liang He ◽  
Fei Gao ◽  
Bao Yun Song ◽  
Rong Fu ◽  
Gui Ming Wu ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Large Scale ◽  
Tensile Tests ◽  
Mg Alloys ◽  
Uniaxial Tensile ◽  
Batch Mode ◽  
Angular Pressing ◽  
Conform Process

Effective grain refinement through equal channel angular pressing (ECAP) for magnesium (Mg) alloys has been demonstrated by many researchers. Although with the capability to achieve superplasticity, the batch mode nature of this method and the required repetitive processing to attain ultrafine grained structure have prohibited it from being widely used in large-scale industrial production. In this study, a well-established metal forming method – the continuous extrusion forming (CONFORM) process – was employed as a severe plastic deformation route to refine the microstructure of Mg alloys. Cast Mg-3%Al-1%Zn (AZ31) rods were used as the feedstock and the cast structure (grain size of ~150 microns) was refined to ~1 micron afteronepass CONFORM extrusion. Uniaxial tensile tests of the as-extruded samples were conducted at a temperature of 473K and an elongation of ~200% was achieved under a strain rate of 1×10-4s-1. The significant grain refinement effect was attributed to the severe shear deformation occurred during the CONFORM process, which is very similar to ECAP but with even higher effective strains. The most important advantage of CONFORM over ECAP is that the former is a continuous route, so it is able to produce long products. It was also shown that CONFORM could be an additional forming method for Mg alloys to conventional rolling, forging and extrusion.

Specific Features of Static, Impact, and Fatigue Fracture of the 0.09%C-0.08%Mo-0.03%Nb-0.06%V Steel with Ultrafine-Grained Structure

2008 ◽  
Vol 584-586 ◽  
pp. 281-286 ◽  
Author(s):  
L.R. Botvina ◽  
Marat R. Tyutin ◽  
V.P. Levin ◽  
Y.A. Demina ◽  
I.A. Panteleev ◽  
...  
Keyword(s):  
Tensile Tests ◽  
Dynamic Fracture Toughness ◽  
Fracture Mechanisms ◽  
Plastic Deformation Zone ◽  
Initial Structure ◽  
Initial State ◽  
Surface Microrelief ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
The Impact

The mechanical properties and fracture mechanisms of the 0.09%C-0.08%Mo-0.03%Nb- 0.06%V steel in the initial state and with the ultrafine-grained (UFG) structure obtained by equalchannel angular pressing (ECAP) have been estimated. The investigation included the static and cyclic tensile tests, the impact tests at room and lower temperatures with automatic recording of force-displacement diagram, and the analysis of both the fracture surface microrelief and the evolution of plastic deformation zone by replica method. It is established that the grain refinement increases the ultimate strength and yield strength, but decreases plasticity and impact toughness and raises fatigue growth rate and the critical temperature of ductile–brittle transition. The dynamic fracture toughness of the material after ECAP as compared with that of the material with the initial structure decreases due to the raising of the critical brittleness temperature.

Measurement of Bauschinger Effect in Ultrafine-Grained A1070 Aluminum Rods

2016 ◽  
Vol 725 ◽  
pp. 202-207 ◽  
Author(s):  
Takayuki Koizumi ◽  
Mitsutoshi Kuroda
Keyword(s):  
Grain Boundaries ◽  
Bauschinger Effect ◽  
Pure Aluminum ◽  
Circular Cross Section ◽  
Dislocation Motion ◽  
Uniaxial Tensile ◽  
Internal Stresses ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Compressive Tests

In this study, the Bauschinger effect in ultrafine-grained pure aluminum rods (A1070) was investigated. The samples were produced by multipass equal-channel angular pressing (ECAP) with ‘route BC’, which is known to give nearly equiaxial-shaped crystal grains. Dumbbell-shaped specimens with a circular cross section were machined from the samples subjected to ECAP to carry out uniaxial tensile and compressive tests, which were followed by reversal of the loading direction at a prestrain of 1%. The influence of the grain size on the intensity of the Bauschinger effect was investigated. The Bauschinger effect is interpreted to be a manifestation of internal stresses produced near the grain boundaries by the accumulation of dislocations. On the basic of our experimental results, the roles of the grain boundaries, which are usually at least partially considered as barriers to dislocation motion, are reconsidered.

Finite Element Simulation of Ductile Failure Process of Spot Welded Joint under Tensile Loading

2014 ◽  
Vol 660 ◽  
pp. 623-627
Author(s):  
Mohamad Shahrul Effendy Kosnan ◽  
Zaini Ahmad ◽  
Abdoulhdi Amhmad Borhana ◽  
Mohd Nasir Tamin
Keyword(s):  
Welded Joint ◽  
Fe Simulation ◽  
Tensile Deformation ◽  
Failure Process ◽  
Damage Model ◽  
Ductile Failure ◽  
Tensile Failure ◽  
Fe Model ◽  
Deformation And Failure ◽  
Spot Welded

Deformation response and failure process of a spot welded joint are investigated in this study. For this purpose, a cross-tension spot welded joint sample made of dual phase steel sheets (DP600) is prepared and tensile tested to failure. Complementary FE simulation of the test is performed. The FE model acknowledges the variation of properties across the spot welded region. Rice-Tracey ductile damage model is approximated and employed in the simulation. Close comparison of load-displacement curves and deformed shape with measured values serve as validation of the FE model. Results show that FE simulation with damage-based model adequately predicts tensile deformation and failure of the spot welded joint. Tensile failure of the joint is confined to the heat affected zone and heat affected/fusion zone interface of the joint. Localized through-thickness necking of the sheet metal is captured. In addition, the predicted fracture of the spot welded joint is accompanied by localized extensive plastic deformation.

scholarly journals Insight Into the Strengthening Mechanism of the Al-Induced Cross-Linked Calcium Aluminosilicate Hydrate Gel: A Molecular Dynamics Study

2021 ◽  
Vol 7 ◽  
Author(s):  
Gaozhan Zhang ◽  
Yang Li ◽  
Jun Yang ◽  
Qingjun Ding ◽  
Daosheng Sun
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Coupling Effect ◽  
Failure Process ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Strengthening Mechanism ◽  
Dynamics Simulation ◽  
Uniaxial Tensile ◽  
Calcium Aluminosilicate

Understanding and controlling the mechanical properties of calcium aluminosilicate hydrate (C-A-S-H) gel is essential to the performance improvement of cementing materials. This study characterizes the mechanical properties and failure mechanism of cross-linked C-A-S-H that have Al/Si ratios ranging from 0 to 0.20 by employing the reactive molecular dynamics simulation. In these constructed C-A-S-H models, the Al-induced cross-linking effect on the aluminosilicate chains is well reproduced. With the incorporation of aluminate species, layered C-S-H structure gradually transforms into three-dimensional C-A-S-H. The uniaxial tensile tests show that Al-induced cross-links significantly increase the cohesive force and stiffness of C-A-S-H along both y- and z-directions. In the C-A-S-H model with the Al/Si ratio equal to 0.2, in which all the bridging sites are cross-linked, the toughness along y-direction significantly improves the interlayer mechanical properties compared to those within the layers. The deformation mechanism of the C-A-S-H structure is also studied. Results show that the depolymerization of the calcium aluminosilicate skeleton is the main route to uptake the loading energy. Both the increase of y- and z-directional strength of the structure can be related to the increasing polymerization of aluminosilicate chains along that direction. This demonstrates the important role of aluminosilicate chains in resisting the external tensile loading. Besides, during the failure process in C-A-S-H elongation, the hydrolysis reactions of calcium silicate skeleton are caused by the coupling effect of loading and interlayer water “attack.” While the Al-O-Si bond breakage results from the protonation of bridging oxygen atom, the hydrolytic reaction of Si-O-Si is initiated by five-coordinate silicon formation. Both pathways weaken the bridging bond and thus result in the breakage of T-O-Si, where T is Al or Si.

scholarly journals Effect of Annealing on the Microstructure, Texture and Mechanical Properties of Severely Deformed Interstitial Free Steel

2012 ◽  
Vol 706-709 ◽  
pp. 1817-1822 ◽  
Author(s):  
Sujoy S. Hazra ◽  
Azdiar A. Gazder ◽  
Elena V. Pereloma
Keyword(s):  
Mechanical Properties ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Interstitial Free ◽  
Abnormal Growth ◽  
Angular Pressing ◽  
Interstitial Free Steel ◽  
Back Scattering ◽  
Cold Rolled ◽  
Shear Punch Testing

Ti-stabilised interstitial free (IF) steel initially subjected to 8 passes, route BCequal channel angular pressing (ECAP) was further cold rolled (CR) at room temperature to 95% thickness reduction. Both samples were isothermally annealed at 710 °C following which their microstructures and micro-textures were compared via electron back-scattering diffraction (EBSD). The mechanical properties first obtained by shear punch testing (SPT) were later corroborated by uniaxial tensile tests. In the case of the ECAP material, continuous recrystallisation is followed by abnormal growth at prolonged annealing times with minor increases in high angle boundary (HAGB) fraction. On the other hand, the additionally CR material shows continuous recrystallisation accompanied by a reduction in the HAGB fraction. After 15 s annealing, the ECAP and CR samples exhibit a good strength-ductility balance; which corresponds to ~52% and ~67% softening, respectively.

scholarly journals Mechanical Properties and Microstructure of a Duplex Nanostructure

2010 ◽  
Vol 667-669 ◽  
pp. 973-978
Author(s):  
L. Chen ◽  
Ping Jiang ◽  
Xiao Lei Wu ◽  
Mu Xin Yang ◽  
Chang Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Yield Strength ◽  
Uniform Elongation ◽  
Tensile Tests ◽  
Coarse Grained ◽  
Uniaxial Tensile ◽  
Plastic Behavior ◽  
Angular Pressing ◽  
Elongation To Failure

The nanostructure was obtained in a duplex stainless steel (DSS) by means of equal channel angular pressing. The mechanical properties were characterized by uniaxial tensile tests, while the microstructure was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was shown that the yield strength in a deformed nanostructure increased significantly from 402 MPa to 1461 MPa as compared to its coarse-grained counterpart. In contrast, the uniform elongation decreased significant to only 2% together with elongation to failure of 9.8%, much lower than those of 25.4% and 42.6%. After annealing at 700°C for 10 minute, however, uniform elongation increases to 5.3% with the yield strength of 1200 MPa. TEM observation exhibited that deformation twins prevail in the austenite phase whereas the dislocations of high density present in ferrite. The plastic behavior in both phases was analyzed based on the deformation twinning and the presence of dislocation. Finally, the effect of the microstructure on mechanical properties was discussed.

scholarly journals An Experimental and Computational Study on the Orthotropic Failure of Separators for Lithium-Ion Batteries

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4399
Author(s):  
Marian Bulla ◽  
Stefan Kolling ◽  
Elham Sahraei
Keyword(s):  
Failure Criterion ◽  
Computational Study ◽  
Short Circuit ◽  
Lithium Ion ◽  
Local Strain ◽  
Damage Mechanism ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Element Analysis ◽  
Deformation And Failure

In the present study, the mechanical properties of a dry-processed polyethylene (PE) separator are investigated in terms of deformation and failure limits. The focus is set on the anisotropic mechanical behavior of this material. A deeper understanding of the damage mechanism is important for further safety and crashworthiness investigations and predictions of damage before failure. It has been found that separator integrity is one of the crucial parts in preventing internal short circuit and thermal runaway in lithium-ion (Li-ion) batteries. Based on uniaxial tensile tests with local strain measurement, a novel failure criterion for finite element analysis (FEA), using the explicit FEA solver Altair Radioss, has been developed to predict the effect of high mechanical loads with respect to triaxiality, large plastic strain and orthotropy. Finally, a simulation model of a PE separator was developed combining the novel failure criterion with Hill’s yield surface and a Swift–Voce hardening rule. The model succeeded in predicting the anisotropic response of the PE separator due to deformation and failure. The proposed failure model can also be combined with other constitutive material laws.

Effect of Ultrasonic Treatment on the Characteristics of Superplasticity of Titanium Alloy Ti-6Al-4V

2018 ◽  
Vol 385 ◽  
pp. 53-58 ◽  
Author(s):  
Asiya Samigullina ◽  
Mariya Murzinova ◽  
Aygul Mukhametgalina ◽  
Alexander P. Zhilyaev ◽  
Ayrat A. Nazarov
Keyword(s):  
Ultrasonic Treatment ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Sensitivity Coefficient ◽  
Strain Rates ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Induced Defects

Effect of ultrasonic treatment (UST) with an amplitude of oscillating tension-compression stresses 100 MPa on the characteristics of superplastic deformation of Ti-6Al-4V alloy with an ultrafine grained (UFG) structure processed by equal-channel angular pressing (ECAP) is studied. During tensile tests at 600°C with initial strain rates in the interval from 10-4 to 10-3 s-1, ultrasonically irradiated samples exhibit a reduced flow stress, higher values of the strain rate sensitivity coefficient and elongation to failure as compared to the samples tested directly after ECAP. Detailed studies of the microstructure of samples subjected to ECAP only and ECAP followed by UST revealed no considerable differences. It is suggested that the UST affected fine structure of the material bringing them to a state with a higher ability of relaxation of deformation-induced defects.

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