Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

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Development of substructure in 1100 aluminum during cold rolling

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011012x ◽

1978 ◽

Vol 36 (1) ◽

pp. 596-597

Author(s):

D.L. Rohr ◽

S.S. Hecker

Keyword(s):

Room Temperature ◽

Mechanical Response ◽

Large Strains ◽

Plastic Response ◽

Final Thickness ◽

Commercially Pure ◽

Thin Foils ◽

Transmission Electron ◽

Aluminum Plates ◽

Comprehensive Study

The plastic response of metals at very large plastic strains is of considerable interest for practical and academic reasons. The question of the existence of a saturation stress remains largely unanswered because most experiments are not carried out to sufficiently large strains. In this paper we report our preliminary findings on the development of substructure in 1100 aluminum during rolling to reductions of 99.8%. This is part of a comprehensive study of microstructure and mechanical response of metals to large uniaxial and biaxial deformations.Commercially pure (1100) aluminum plates, annealed at 500°C, were rolled at room temperature from various starting thicknesses to a final thickness of 0.127 mm in a 2-high laboratory rolling mill. Sheets with final reductions ranging from 9.1 to 99.8% were examined by transmission electron microscopy. Thin foils were prepared directly from the 0.127-mm thick sheets by electropolishing with a 50cc-50cc-2cc HNO3-CH3OH-HCl solution in a jet polisher.

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Microstructural Characterization of Chip Segmentation Under Different Machining Environments in Orthogonal Machining of Ti6Al4V

Journal of Engineering Materials and Technology ◽

10.1115/1.4028841 ◽

2015 ◽

Vol 137 (1) ◽

Cited By ~ 29

Author(s):

Shashikant Joshi ◽

Asim Tewari ◽

Suhas S. Joshi

Keyword(s):

Plastic Strain ◽

Room Temperature ◽

Microstructural Analysis ◽

Cutting Speed ◽

Microstructural Characterization ◽

Shear Plane ◽

Band Formation ◽

Orthogonal Machining ◽

Two Temperatures ◽

Experimental Values

Segmented chips are known to form in machining of titanium alloys due to localization of heat in the shear zone, which is a function of machining environment. To investigate the correlation between machining environments and microstructural aspects of chip segmentation, orthogonal turning experiments were performed under three machining environments, viz., room, LN2, and 260 °C. Scanning electron and optical microscopy of chip roots show that the mechanism of chip segment formation changes from plastic strain and mode II fracture at room temperature, to predominant mode I fracture at LN2 and plastic strain leading to shear band formation at 260 °C. The chip segment pitch and shear plane length predicted using Deform™ matched well with the experimental values at room temperature. The microstructural analysis of chips show that higher shear localization occurs at room temperature than the other two temperatures. The depth of machining affected zone (MAZ) on work surfaces was lower at the two temperatures than that of at the room temperature at a higher cutting speed of 91.8 m/min.

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Biaxial Strength of HY 80 Steel

Journal of Engineering Materials and Technology ◽

10.1115/1.3225788 ◽

1985 ◽

Vol 107 (2) ◽

pp. 132-137 ◽

Cited By ~ 2

Author(s):

K. S. Chan ◽

U. S. Lindholm ◽

J. Wise

Keyword(s):

Biaxial Tension ◽

Strain Ratio ◽

Thin Wall ◽

Plastic Strain Ratio ◽

Axial Tension ◽

Diffuse Necking ◽

Stress States ◽

Von Mises ◽

Tube Geometry ◽

Good Agreement

The biaxial deformation behavior of HY 80 steel has been examined by testing thin wall tubes under combined axial tension and internal pressure. The effective stress-strain curves and the hardening response have been found to vary with the stress state. The plastic strain ratio at a given stress ratio deviates from the von Mises value except at the stress states near uniaxial tension, plane strain and equi-biaxial tension. Using Drucker theory, these deviations are eliminated and the resulting yield locus is in good agreement with both the Bishop-Hill theory and the experimental results. Influenced by the tube geometry, the instability strains at the onset of diffuse necking are decreased by an increase in hoop tension. The diffuse necking strains are reasonably predicted by the Swift and the Lankford-Saibel/Mellor criteria.

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COMPRESSION OF ECAPED TITANIUM MICRO-PILLARS FOR TWO PRINCIPAL ORIENTATIONS

Acta Polytechnica CTU Proceedings ◽

10.14311/app.2020.27.0001 ◽

2020 ◽

Vol 27 ◽

pp. 1-5

Author(s):

David Vokoun ◽

Jan Maňák ◽

Karel Tesař ◽

Stanislav Habr

Keyword(s):

Room Temperature ◽

Focused Ion Beam ◽

Mechanical Response ◽

Thermomechanical Processing ◽

Ion Beam ◽

Orientation Dependence ◽

Material Strength ◽

Angular Pressing ◽

Macro Scale ◽

Micro Pillars

The thermomechanical processing by equal-channel angular pressing (ECAP) is used for certain metals and alloys in order to make their structure fine and to increase material strength. In the previous study done at our institute, grade 2 titanium was successfully processed using four consecutive route A passes via a 90 ° ECAP die with high backpressure at room temperature. Orientation dependence of compressive and tensile loading of ECAPed titanium samples was demonstrated at macro-scale. However, scarce attention has been paid so far to the mechanical behavior of ECAPed titanium samples at micro-scale. In the present study, compression experiments on titanium micropillars, fabricated using focused ion beam, are carried out for two main directions in respect to preceding ECAP pressing (insert and extrusion directions). The purpose of this study is to discuss the orientation dependence of mechanical response during compression of the as-ECAPed titanium micro-pillars.

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The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

MRS Proceedings ◽

10.1557/proc-806-mm7.5 ◽

2003 ◽

Vol 806 ◽

Author(s):

Wendelin J. Wright ◽

R. H. Dauskardt ◽

W. D. Nix

Keyword(s):

Plastic Strain ◽

Metallic Glasses ◽

Room Temperature ◽

Tensile Axis ◽

Uniaxial Stress ◽

Temperature Deformation ◽

Steel Alloys ◽

Cyclic Torsion ◽

Perfectly Plastic ◽

Elastic Perfectly Plastic

ABSTRACTThe major mechanical shortcoming of metallic glasses is their limited ductility at room temperature. Monolithic metallic glasses sustain only a few percent plastic strain when subjected to uniaxial compression and essentially no plastic strain under tension. Here we describe a room temperature deformation process that may have the potential to overcome the limited ductility of monolithic metallic glasses and achieve large plastic strains. By subjecting a metallic glass sample to cyclic torsion, the glass is brought to the yield surface; the superposition of a small uniaxial stress (much smaller than the yield stress) should then produce increments in plastic strain along the tensile axis. This accumulation of strain during cyclic loading, commonly known as ratcheting, has been extensively investigated in stainless and carbon steel alloys, but has not been previously studied in metallic glasses. We have successfully demonstrated the application of this ratcheting technique of cyclic torsion with superimposed tension for polycrystalline Ti–6Al–4V. Our stability analyses indicate that the plastic deformation of materials exhibiting elastic–perfectly plastic constitutive behavior such as metallic glasses should be stable under cyclic torsion, however, results obtained thus far are inconclusive.

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Mechanical response of all-MoS2 single-layer heterostructures: a ReaxFF investigation

Physical Chemistry Chemical Physics ◽

10.1039/c6cp03612k ◽

2016 ◽

Vol 18 (34) ◽

pp. 23695-23701 ◽

Cited By ~ 39

Author(s):

Bohayra Mortazavi ◽

Alireza Ostadhossein ◽

Timon Rabczuk ◽

Adri C. T. van Duin

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Mechanical Response ◽

Single Layer ◽

Layer Structures

Mechanical properties of all-MoS2 single-layer structures at room temperature are explored using ReaxFF simulations.

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Thermal Stability of Magnetic Properties in Dehydrogenated Triarylmethane Resins

MRS Proceedings ◽

10.1557/proc-173-71 ◽

1989 ◽

Vol 173 ◽

Author(s):

Michiya Otani ◽

Sugio Otani

Keyword(s):

Thermal Stability ◽

Magnetic Properties ◽

Magnetic Property ◽

Room Temperature ◽

Permanent Magnets ◽

Elevated Temperatures ◽

Mechanical Response ◽

The Stability ◽

Thermal Stability Of

ABSTRACTThe stability of the magnetic properties of dehydrogenated triaryl-methane resins was investigated both at room temperature and at elevated temperatures. A magnetic property different from that reported in a previous paper was found in the course of studying the reproducibility of synthesis. This new property was examined through a mechanical response of the resins to a set of permanent magnets.

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Effect of Combined Stress on Yield and Fracture Behavior of Zircaloy-2

Journal of Basic Engineering ◽

10.1115/1.3662246 ◽

1961 ◽

Vol 83 (4) ◽

pp. 499-508 ◽

Cited By ~ 26

Author(s):

R. L. Mehan

Keyword(s):

Plastic Flow ◽

Biaxial Tension ◽

Effective Strain ◽

Tension Stress ◽

Combined Stress ◽

Flow Properties ◽

Axial Tension ◽

Fracture Ductility ◽

Stress States ◽

Single Stress

The yielding and fracture characteristics of Zircaloy-2 as a function of stress state were investigated at room temperature through the medium of thin-walled cylindrical specimens under internal pressure and axial tension. Stress states from uniaxial longitudinal tension to uniaxial tangential tension were examined. Two tests at elevated temperature were performed at a single stress ratio. It was found that the fracture ductility lessened with increasing biaxiality. A minimum in ductility was found at balanced biaxial tension where the fracture ductility, as expressed by the effective strain, was 29 per cent. The yielding and plastic flow properties were found to be highly anisotropic. Two methods were used to express the plastic flow data: a graphical approach and a theoretical analysis based on a theory proposed by R. Hill, either one of which is suitable to express the flow properties of Zircaloy-2 under various states of combined stress.

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Numerical Analysis and Mechanical Properties of Nomex™ Honeycomb Core

Volume 14: Emerging Technologies; Materials: Genetics to Structures; Safety Engineering and Risk Analysis ◽

10.1115/imece2017-72654 ◽

2017 ◽

Author(s):

Yue Liu ◽

Weicheng Gao ◽

Wei Liu ◽

Zhou Hua

Keyword(s):

Compressive Strength ◽

Cell Walls ◽

Mechanical Response ◽

Compressive Loading ◽

Fe Model ◽

Honeycomb Core ◽

Practical Applications ◽

Honeycomb Sandwich ◽

Nomex Honeycomb ◽

Strength And Stiffness

This paper presents an investigation on the mechanical response of the Nomex honeycomb core subjected to flatwise compressive loading. Thin plate elastic in-plane compressive buckling theory is used to analyze the Nomex honeycomb core cell wall. A mesoscopic finite element (FE) model of honeycomb sandwich structure with the Nomex honeycomb cell walls is established by employing ABAQUS/Explicit shell elements. The compressive strength and compressive stiffness of Nomex honeycomb core with different heights and thickness of cell walls, i.e. double cell walls and single cell walls, are analyzed numerically using the FE model. Flatwise compressive tests are also carried out on bare honeycomb cores to validate the numerical method. The results suggest that the compressive strength and compression stiffness are related to the geometric dimensions of the honeycomb core. The Nomex honeycomb core with a height of 6 mm has a higher strength than that of 8 mm. In addition, the honeycomb core with lower height possesses stronger anti-instability ability, including the compressive strength and stiffness. The proposed mesoscopic model can effectively simulate the crushing process of Nomex honeycomb core and accurately predict the strength and stiffness of honeycomb sandwich panels. Our work is instructive to the practical applications in engineering.

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