scholarly journals The plastic deformation of iron and the formation of Neumann lines

1925 ◽  
Vol 108 (745) ◽  
pp. 231-231
Keyword(s):  
Plastic Deformation ◽  
Pure Iron ◽  
Crystal Surfaces ◽  
Size And Shape ◽  
Slip Bands ◽  
Wide Range ◽  
Moderate Rate ◽  
Rapid Deformation

The object of the investigation described in the present paper was to ascertain the manner in which wide variations in speed affect the mechanism of deformation in plastic metals. Iron was selected as the first metal for experiment, mainly because it is known that rapid deformation produced by shock is accompanied in this metal by special features, known as Neumann lines or lamellæ. When a piece of nearly pure iron, of suitable size and shape, with one face polished and etched, is subsequently subjected to plastic deformation at a moderate rate, the crystal surfaces, when examined under the microscope after deformation, show the well-known appearance of slip bands (1). The present experiments were undertaken in the first instance to ascertain whether the character, number and appearance of such slip bands would be appreciably affected by varying the rate of deformation over a wide range. For the sake of convenience, deformation by compression has been employed, the metal being used in the form of small rectangular prisms, measuring in some instances 0.44 inch by 0.44 inch in section by 0.7 inch in height.

scholarly journals The plastic deformation of iron and the formation of Neumann lines

1925 ◽  
Vol 108 (746) ◽  
pp. 231-239 ◽  
Keyword(s):  
Plastic Deformation ◽  
Testing Machine ◽  
Hardened Steel ◽  
Guard Ring ◽  
Crystal Surfaces ◽  
Slip Bands ◽  
Wide Range ◽  
Moderate Rate ◽  
Falling Weight ◽  
Rapid Deformation

The object of the investigation described in the present paper was to ascertain the manner in which wide variations in speed affect the mechanism of deformation in plastic metals. Iron was selected as the first metal for experiment, mainly because it is known that rapid deformation produced by shock is accompanied in this metal by special features, known as Neumann lines or lamellæ. When a piece of nearly pure iron, of suitable size and shape, with one face polished and etched, is subsequently subjected to plastic deformation at a moderate rate, the crystal surfaces, when examined under the microscope after deformation, show the well-known appearance of slip bands (1). The present experiments were undertaken in the first instance to ascertain whether the character, number and appearance of such slip bands would be appreciably affected by varying the rate of deformation over a wide range. For the sake of convenience, deformation by compression has been employed, the metal being used in the form of small rectangular prisms, measuring in some instances 0·44 inch by 0·44 inch in section by 0·7 inch in height, and 0·3 inch by 0·3 inch in section and 0·5 inch in height. These were prepared with considerable care, particularly in regard to their length, and the amount of deformation applied to them was measured in every case. In the majority of experiments these small prisms were placed in a compression testing machine, and were surrounded by a hardened steel ring of such size as to limit the deformation exactly to the desired amount. A similar guard-ring was employed in connection with deformation by a blow from a falling weight. The actual amount of deformation could be varied, while still employing the same ring, by inserting small flat strips of hardened steel as packing-pieces under the specimen of iron.

Failure analysis of laser-textured surfaces

2000 ◽  
Vol 214 (5) ◽  
pp. 471-483 ◽  
Author(s):  
S Chilamakuri ◽  
X Zhao ◽  
B Bhushan
Keyword(s):  
Plastic Deformation ◽  
Operating Conditions ◽  
Disk Drives ◽  
Critical Number ◽  
Textured Surfaces ◽  
Tribological Behaviour ◽  
Magnetic Disk ◽  
Size And Shape ◽  
Ultrahigh Density ◽  
Theoretical Results

Friction/stiction behaviour of ultrahigh-density magnetic disk drives can be controlled by controlling the size and shape of the laser bumps. Tribological behaviour of laser-textured disk surfaces depends on the size and shape of the laser bumps, bump density and operating conditions. In this study, theoretical and experimental analyses have been carried out on nine different laser-textured disk surfaces. Stiction and friction experiments have been carried out on sombrero, V-type and W-type laser-textured disks and these results are compared with theoretical results. A good correlation is obtained between experimental and theoretical results. The effect of laser bump uniformity on critical number of bumps required to prevent plastic deformation and stiction has also been studied.

The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

2007 ◽  
Vol 558-559 ◽  
pp. 1283-1294 ◽  
Author(s):  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Metallic Materials ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Ultrafine Grained Materials ◽  
Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

Dependence of Scintillators Optical Properties on Intrinsic Structural Defects

1994 ◽  
Vol 348 ◽  
Author(s):  
N.V. Kilassen
Keyword(s):  
Plastic Deformation ◽  
Optical Properties ◽  
Crystal Growth ◽  
Spectral Distribution ◽  
Light Output ◽  
Structural Defects ◽  
High Quality ◽  
Intrinsic Defects ◽  
Distribution Kinetics ◽  
Wide Range

ABSTRACTThe studies of the dependence of the optical properties of various scintillators on intrinsic structural defects have been reviewed. The greater part of the review is devoted to the defects introduced by plastic deformation. A wide range of variations in the light output, spectral distribution, kinetics and other properties has been observed. These defects can be induced during crystal growth, annealing, processing, etc. The proper regulation of the superstructure of intrinsic defects can ensure the production of high quality scintillators having required properties.

scholarly journals Initial stages of yield in nanoindentation

1999 ◽  
Vol 14 (6) ◽  
pp. 2219-2227 ◽  
Author(s):  
J. D. Kiely ◽  
K. F. Jarausch ◽  
J. E. Houston ◽  
P. E. Russell
Keyword(s):  
Plastic Deformation ◽  
Plastic Zone ◽  
Applied Load ◽  
Elastic Behavior ◽  
Load Relaxation ◽  
Crystal Surfaces ◽  
Small Deviations ◽  
Single Crystal Surfaces ◽  
Complete Relaxation ◽  
Interfacial Force

We have used the interfacial force microscope to perform nanoindentations on Au single-crystal surfaces. We have observed two distinct regimes of plastic deformation, which are distinguished by the magnitude of discontinuities in load relaxation. At lower stresses, relaxation occurs in small deviations from elastic behavior, while at the higher stresses they take the form of large load drops, often resulting in complete relaxation of the applied load. These major events create a relatively wide plastic zone that subsequently deepens more rapidly than it widens. We discuss these findings in terms of contrasting models of dislocation processes in the two regimes.

Improving the efficiency of electromechanical processing by surface plastic deformation

2021 ◽  
pp. 16-22
Author(s):  
N.G. Dudkina ◽  
I.N. Zakharov ◽  
V. V. Barinov
Keyword(s):  
Plastic Deformation ◽  
Surface Plastic Deformation ◽  
Carbon Steels ◽  
Scientific School ◽  
Surface Plastic ◽  
State Technical ◽  
Effective Combination ◽  
Wide Range ◽  
Long Time ◽  
Selection Of

The article provides an overview of the experimental research developments of the recent years of the scientific school of the Volgograd State Technical University in the field of combined surface hardening of metals by electromechanical processing (EMP) in combination with surface plastic deformation (SPD). For a long time, the authors have been developing a scientifically based approach to the selection of an effective combination of technological effects based on electromechanical processing using surface plastic deformation on the surface layer of medium- and high-carbon steels. The advantage of the combined technologies based on EMP is the possibility to control the quality, structure, physical-mechanical and operational properties within a wide range by changing the hardening modes.

scholarly journals Fracture toughness of wet and dry particulate materials comprised of colloidal sized particles: role of plastic deformation

Soft Matter ◽  
2017 ◽  
Vol 13 (27) ◽  
pp. 4746-4755 ◽  
Author(s):  
Mitchell L. Sesso ◽  
George V. Franks
Keyword(s):  
Fracture Toughness ◽  
Plastic Deformation ◽  
Particulate Materials ◽  
Wide Range

This work demonstrates a method of measuring the fracture toughness of particulate materials comprised of colloidal sized particles over a wide range of saturation.

A Model for the Conductivity and Compliance of Unpropped and Natural Fractures

SPE Journal ◽  
2017 ◽  
Vol 22 (06) ◽  
pp. 1893-1914 ◽  
Author(s):  
Weiwei Wu ◽  
Mukul M. Sharma
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Correlation Length ◽  
Young's Modulus ◽  
Heterogeneous Surfaces ◽  
Natural Fractures ◽  
Wide Range ◽  
Fracture Closure ◽  
Deformation Interaction

Summary Fluid flow in unpropped and natural fractures is critical in many geophysical processes and engineering applications. The flow conductivity in these fractures depends on their closure under stress, which is a complicated mechanical process that is challenging to model. The challenges come from the deformation interaction and the close coupling among the fracture geometry, pressure, and deformation, making the closure computationally expensive to describe. Hence, most of the previous models either use a small grid system or disregard deformation interaction or plastic deformation. In this study, a numerical model is developed to simulate the stress-driven closure and the conductivity for fractures with rough surfaces. The model integrates elastoplastic deformation and deformation interaction, and can handle contact between heterogeneous surfaces. Computation is optimized and accelerated by use of an algorithm that combines the conjugate-gradient (CG) method and the fast-Fourier-transform (FFT) technique. Computation time is significantly reduced compared with traditional methods. For example, a speedup of five orders of magnitude is obtained for a grid size of 512 × 512. The model is validated against analytical problems and experiments, for both elastic-only and elastoplastic scenarios. It is shown that interaction between asperities and plastic deformation cannot be ignored when modeling fracture closure. By applying our model, roughness and yield stress are found to have a larger effect on fracture closure and compliance than Young's modulus. Plastic deformation is a dominant contributor to closure and can make up more than 70% of the total closure in some shales. The plastic deformation also significantly alters the relationship between fracture stiffness and conductivity. Surfaces with reduced correlation length produce greater conductivity because of their larger apertures, despite more fracture closure. They have a similar fraction of area in contact as compared with surfaces with longer fracture length, but the pattern of area in contact is more scattered. Contact between heterogeneous surfaces with more soft minerals leads to increased plastic deformation and fracture closure, and results in lower fracture conductivity. Fracture compliance appears not to be as sensitive to the distribution pattern of hard and soft minerals. Our model compares well with experimental data for fracture closure, and can be applied to unpropped or natural fractures. These results are obtained for a wide range of conditions: surface profile following Gaussian distribution with correlation length of 50 µm and roughness of 4 to 50 µm, yield stress of 100 to 1500 MPa, and Young's modulus of 20 to 60 GPa. The results may be different for situations outside this range of parameters.

Plasticity and Microstructure of Irradiated Pd

1998 ◽  
Vol 540 ◽  
Author(s):  
N. Baluc ◽  
Y. Dai ◽  
M. Victoria
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Ambient Temperature ◽  
Tensile Deformation ◽  
Microscopic Level ◽  
Macroscopic Scale ◽  
Slip Bands ◽  
Transmission Electron ◽  
Mev Protons

AbstractSingle crystalline specimens of pure Pd have been irradiated at ambient temperature with 590 MeV protons to doses ranging between 10−4 and 10−1 dpa. Tensile deformation experiments revealed that irradiation induces hardening and embrittlement, while scanning (SEM) and transmission electron microscopy (TEM) observations showed that plastic deformation of specimens irradiated to a dose ≥ 10−2 dpa is strongly localized and yields the creation of slip bands at the macroscopic scale and of defect-free channels at the microscopic level.

The Semicircular Canals of the Inner Ear and the Pneumatization of the Temporal Bone

1986 ◽  
Vol 27 (3) ◽  
pp. 325-329
Author(s):  
C. Muren ◽  
H. Wilbrand
Keyword(s):  
Inner Ear ◽  
Temporal Bone ◽  
Semicircular Canals ◽  
Petrous Bone ◽  
General Outline ◽  
Size And Shape ◽  
Wide Range

In an investigation of 94 plastic casts of temporal bone specimens a wide range of variations both in the general outline of the pyramid and in the anatomy of its specific structures was found. Attempts were made to estimate the transverse and vertical dimensions of the petrous bone. Both the mastoid and the perilabyrinthine pneumatization correlated to the dimensions of some structures, but not to the size and shape of the semicircular canals. References

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