The Effect of Strain Rate and Temperature on Yielding in Steels

The Effect of Strain Rate and Temperature on Yielding in Steels PDF Author: David P. Kendall
Publisher:
ISBN:
Category :
Languages : en
Pages : 35

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Book Description
The effect of elastic strain rates ranging from 0.001 to 10/sec and temperatures ranging from 200K ( -100F) to 590K (600F) on the yield strength of several steels is reported. The steels utilized are a 1018 mild steel, 4340 steel, H-11 tool steel and 300 grade maraging steel. The results are interpreted in terms of the Cottrel-Bilby yielding model based on release of dislocations from locking carbon atmospheres. The results for all of the materials except the maraging steel are consistent with this model if it is modified to account for re-locking of dislocations by migration of carbon atoms. The maraging steel shows a constant strain rate sensitivity at a constant temperature, over the range of strain rates investigated. This rate sensitivity decreases with increasing temperature and at 590K (600 F) a decreasing strength with increasing strain rate is found. This is attributed to stress aging effects. (Author).

The Effect of Strain Rate and Temperature on Yielding in Steels

The Effect of Strain Rate and Temperature on Yielding in Steels PDF Author: David P. Kendall
Publisher:
ISBN:
Category :
Languages : en
Pages : 35

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Book Description
The effect of elastic strain rates ranging from 0.001 to 10/sec and temperatures ranging from 200K ( -100F) to 590K (600F) on the yield strength of several steels is reported. The steels utilized are a 1018 mild steel, 4340 steel, H-11 tool steel and 300 grade maraging steel. The results are interpreted in terms of the Cottrel-Bilby yielding model based on release of dislocations from locking carbon atmospheres. The results for all of the materials except the maraging steel are consistent with this model if it is modified to account for re-locking of dislocations by migration of carbon atoms. The maraging steel shows a constant strain rate sensitivity at a constant temperature, over the range of strain rates investigated. This rate sensitivity decreases with increasing temperature and at 590K (600 F) a decreasing strength with increasing strain rate is found. This is attributed to stress aging effects. (Author).

Effects of Moderately High Strain Rates on the Tensile Properties of Metals

Effects of Moderately High Strain Rates on the Tensile Properties of Metals PDF Author: D. P. Moon
Publisher:
ISBN:
Category : Metals
Languages : en
Pages : 38

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Book Description


The Effect of Strain Rate on Yielding in High-strength Steels

The Effect of Strain Rate on Yielding in High-strength Steels PDF Author: David P. Kendall
Publisher:
ISBN:
Category :
Languages : en
Pages : 35

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Book Description
The effect of strain rates ranging from 0.0001 to 10 in/in/sec. on the yield strengths of several high strength alloy steels is investigated. Quenched and tempered type alloys exhibit two regions of strain rate sensitivity with the strain rate dividing the sensitive and insensitive regions varying from 0.5 to greater than 10 in/in/sec, depending on composition, microstructure and grain size. At the higher rates a power law relationship is found which is consistent with a yielding model involving breakaway of dislocations from solute atmospheres. Maraging steel exhibits a continuous power law strain rate sensitivity over the entire range. (Author).

Introduction to Unified Mechanics Theory with Applications

Introduction to Unified Mechanics Theory with Applications PDF Author: Cemal Basaran
Publisher: Springer Nature
ISBN: 3030577724
Category : Science
Languages : en
Pages : 452

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Book Description
This text describes the mathematical formulation and proof of the unified mechanics theory (UMT) which is based on the unification of Newton’s laws and the laws of thermodynamics. It also presents formulations and experimental verifications of the theory for thermal, mechanical, electrical, corrosion, chemical and fatigue loads, and it discusses why the original universal laws of motion proposed by Isaac Newton in 1687 are incomplete. The author provides concrete examples, such as how Newton’s second law, F = ma, gives the initial acceleration of a soccer ball kicked by a player, but does not tell us how and when the ball would come to a stop. Over the course of Introduction to Unified Mechanics Theory, Dr. Basaran illustrates that Newtonian mechanics does not account for the thermodynamic changes happening in a system over its usable lifetime. And in this context, this book explains how to design a system to perform its intended functions safely over its usable life time and predicts the expected lifetime of the system without using empirical models, a process currently done using Newtonian mechanics and empirical degradation/failure/fatigue models which are curve-fit to test data. Written as a textbook suitable for upper-level undergraduate mechanics courses, as well as first year graduate level courses, this book is the result of over 25 years of scientific activity with the contribution of dozens of scientists from around the world including USA, Russia, Ukraine, Belarus, Spain, China, India and U.K.

The Influence of Temperature and Rate of Strain on the Properties of Metals in Torsion

The Influence of Temperature and Rate of Strain on the Properties of Metals in Torsion PDF Author: Clyde Everette Work
Publisher:
ISBN:
Category : Metals
Languages : en
Pages : 316

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Book Description


Viscoelastic Properties of Polymers

Viscoelastic Properties of Polymers PDF Author: John D. Ferry
Publisher: John Wiley & Sons
ISBN: 9780471048947
Category : Technology & Engineering
Languages : en
Pages : 676

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Book Description
Viscoelastic behavior reflects the combined viscous and elastic responses, under mechanical stress, of materials which are intermediate between liquids and solids in character. Polymers the basic materials of the rubber and plastic industries and important to the textile, petroleum, automobile, paper, and pharmaceutical industries as well exhibit viscoelasticity to a pronounced degree. Their viscoelastic properties determine the mechanical performance of the final products of these industries, and also the success of processing methods at intermediate stages of production. Viscoelastic Properties of Polymers examines, in detail, the effects of the many variables on which the basic viscoelastic properties depend. These include temperature, pressure, and time; polymer chemical composition, molecular weight and weight distribution, branching and crystallinity; dilution with solvents or plasticizers; and mixture with other materials to form composite systems. With guidance by molecular theory, the dependence of viscoelastic properties on these variables can be simplified by introducing certain ancillary concepts such as the fractional free volume, the monomeric friction coefficient, and the spacing between entanglement loci, to provide a qualitative understanding and in many cases a quantitative prediction of how to achieve desired results. The phenomenological theory of viscoelasticity which permits interrelation of the results of different types of experiments is presented first, with many useful approximation procedures for calculations given. A wide variety of experimental methods is then described, with critical evaluation of their applicability to polymeric materials of different consistencies and in different regions of the time scale (or, for oscillating deformations, the frequency scale). A review of the present state of molecular theory follows, so that viscoelasticity can be related to the motions of flexible polymer molecules and their entanglements and network junctions. The dependence of viscoestic properties on temperature and pressure, and its descriptions using reduced variables, are discussed in detail. Several chapters are then devoted to the dependence of viscoelastic properties on chemical composition, molecular weight, presence of diluents, and other features, for several characteristic classes of polymer materials. Finally, a few examples are given to illustrate the many potential applications of these principles to practical problems in the processing and use of rubbers, plastics, and fibers, and in the control of vibration and noise. The third edition has been brought up to date to reflect the important developments, in a decade of exceptionally active research, which have led to a wider use of polymers, and a wider recognition of the importance and range of application of viscoelastic properties. Additional data have been incorporated, and the book s chapters on dilute solutions, theory of undiluted polymers, plateau and terminal zones, cross-linked polymers, and concentrated solutions have been extensively rewritten to take into account new theories and new experimental results. Technical managers and research workers in the wide range of industries in which polymers play an important role will find that the book provides basic information for practical applications, and graduate students in chemistry and engineering will find, in its illustrations with real data and real numbers, an accessible introduction to the principles of viscoelasticity.

Yield Point Phenomena in Metals and Alloys

Yield Point Phenomena in Metals and Alloys PDF Author: E. Hall
Publisher: Springer Science & Business Media
ISBN: 1468418602
Category : Technology & Engineering
Languages : en
Pages : 312

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Book Description
Exceptions to the rule are always interesting, and the anomalies in the stress-strain curves of mild steel and in many other metals and alloys have excited the curiosity of engineers and scientists for well over a hundred years. Yet it is only during the last twenty years that significant theoretical advances have been made, and the aim of this book has been to examine these theories against the background of the considerable volume of experimental results published over the last few years, up to mid-1969. Hence this review volume has a two-fold aim; the first chapter attempts to review the general theories of yield point phenomena, using sufficient examples only to illustrate the theories. This chapter is intended to be complete in itself, and could be read by under graduates who wish to appraise rapidly the general background to the problem. The remaining chapters deal, in turn, with the various alloys exhibiting yield point phenomena. Thus, chapter 2 on mild steel, is a more extensive study of quench and strain ageing, while Chapter 3 is on the refractory metals and discusses theories of the low-temperature strength. The next concerns hydrogen in meta-Is. Chapters 5 and 6 discuss the face-centred cubic alloys, particularly the cases of the unloading yield point and intermetallic compounds. Chapter 7 covers hexagonal and ionic structures. A brief final chapter considers the areas where further research may be fruitful.

An Evaluation of Some Current Practices for Short-time Elevated-temperature Tensile Tests of Metals

An Evaluation of Some Current Practices for Short-time Elevated-temperature Tensile Tests of Metals PDF Author: Charles R. Manning
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 48

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Book Description
The effect of different testing practices on the short-time elevated-temperature tensile properties was determined for 2024-T3 aluminum-alloy, HM21A-T8 and HK31A-H24 magnesium-alloy, and 12 MoV stainless-steel sheet. Tests were made under single strain-rate and single head-speed conditions. A dual strain-rate test was also included. An evaluation of the effects of these practices is given for the tensile and yield strengths, the elongation in 2 inches, and the uniform elongation. The need for a uniform testing practice is demonstrated. Recommended practices suggested by different organizations are included.

Strain-Rate Effects on the Ductile/Brittle Transition in Steels

Strain-Rate Effects on the Ductile/Brittle Transition in Steels PDF Author: GA. Knorovsky
Publisher:
ISBN:
Category : Crack initiation
Languages : en
Pages : 28

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Book Description
A recently implemented fracture control plan for structural steel high-way bridges makes use of a linear relation to describe the effect of strain rate on the ductile/brittle transition temperature as a function of yield strength. Literature data show that the predictions of the aforementioned relation are not general. An alternative analysis is offered along with a qualitative model for understanding the phenomenon. Results of an experimental program investigating microstructural effects on the ductile/brittle strain rate dependence are also presented. The results exhibit linear behavior of ?Tdb versus ??/?, where ?Tdb is the transition temperature shift, ? is the yield stress, and ?? is the change in yield stress caused by strain rate. The magnitude of the temperature shift, however, is dependent upon the test specimen used. Factors discussed include microstructure, type of test specimen (Charpy V-notch, nil ductility temperature [NDT], modified NDT, or compact toughness), crack initiation versus crack propagation, and implications for regulatory bodies.

Matter and Methods at Low Temperatures

Matter and Methods at Low Temperatures PDF Author: Frank Pobell
Publisher: Springer Science & Business Media
ISBN: 366208578X
Category : Science
Languages : en
Pages : 328

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Book Description
The aim of this book is to provide information about performing experi ments at low temperatures, as well as basic facts concerning the low tem perature properties of liquid and solid matter. To orient the reader, I begin with chapters on these low temperature properties. The major part of the book is then devoted to refrigeration techniques and to the physics on which they are based. Of equal importance, of course, are the definition and measurement of temperature; hence low temperature thermometry is extensively discussed in subsequent chapters. Finally, I describe a variety of design and construction techniques which have turned out to be useful over the years. The content of the book is based on the three-hour-per-week lecture course which I have given several times at the University of Bayreuth between 1983 and 1991. It should be particularly suited for advanced stu dents whose intended masters (diploma) or Ph.D. subject is experimental condensed matter physics at low temperatures. However, I believe that the book will also be of value to experienced scientists, since it describes sev eral very recent advances in experimental low temperature physics and technology, for example, new developments in nuclear refrigeration and thermometry.