Lecture 18 Strain Hardening And Recrystallization
|
|
- Edmund Harris
- 7 years ago
- Views:
Transcription
1 -138- Lecture 18 Strain Hardening And Recrystallization Strain Hardening We have previously seen that the flow stress (the stress necessary to produce a certain plastic strain rate) increases with increasing plastic strain as σ t = κ' ε t m 18.1 Now we realize that the plastic strain is produced by the motion of dislocations, we should eamine the microscopic basis for this strain hardening behavior. A logical first step is to eamine the dislocations in a highly strain hardened metal. We can do that (at least in thin foils of metal) using the transmission electron microscope (TEM). Please see: ructurevg.html Figure 18.1 (Courtesy C. Cho) A typical TEM micrograph of a heavily deformed metal (in this case Al) is shown in Figure One can see very dense regions of dark lines (the dislocations) surrounding other regions which have very few dislocations. This structure is called a cell structure and the dense dislocation regions are called cell walls. These are tangles of immobile dislocations (if they were able to move the dislocations would glide out of the thin foil). If we want to produce more plastic strain we must produce fresh dislocation from dislocation sources and push these through the tangled immobile dislocations of the cell structure. This process requires more applied stress (more force on the dislocation) than to push a fresh dislocation through a region free of dislocation tangles. The (immobile) dislocation density in the cell structure increases with plastic strains. In fact below a certain strain dense tangles are not formed. An eample of this increase in dislocation density with strain is shown in Figure See ationcellstemvg.html
2 -139- Figure 18.2 From: A.S. Keh in Direct Observations of Imperfections in Crystals ed J.B. Neukirk and J.H. Wernick (1962, Metallurgical Society AIME, Interscience Pub.) p.216. The increasing density of immobile dislocations in the cell walls as the plastic strain increases makes these walls or tangles more effective obstacles to fresh dislocation motion. Hence the flow stress increases resulting in the observed strain hardening. Although many details of the nature of the interactions between the fresh dislocations and the tangles are obscure (for some eamples, see Barrett, Ni and Tetelman p.270 & 271) the increase in flow stress is predicted to be proportional to the square root of overall dislocation density ρ (since fresh dislocations are present at much lower density than the immobile dislocations, ρ ρ immobile ). In fact all theories predict σt = σ o + α Gb ρ 18.2 where G is the shear modulus, b is the magnitude of the dislocation Burger vector and α is a constant which varies from theory to theory but which is approimately equal to 0.2. Eperimentally this relation is obeyed quite well as can be seen from Figure 18.3 which shows typical data for copper τ G b ρ 10-3 Figure 18.3 Effect of dislocation density on the flow stress of polycrystalline copper.
3 -140- All that is necessary to finally describe strain hardening then is to know how ρ (the density of immobile dislocations in the cell structure) builds up with plastic strain ε p. Unfortunately this is difficult to predict since the dislocation tangles form statistically (especially in single crystals). In polycrystals however (where multiple slip occurs even at low strains) one finds that 2 m ρ = ρ o + κ ε p 18.3 If one substitutes ρ from Eq into Eq and makes the approimation that ρ o and σ y are small compared to ρ and σ t one arrives at the empirical equation for strain hardening, Eq A particularly interesting application of these ideas is the prediction of the strain hardening behavior of metals with hard uncuttable particles. We learned in Lecture 13 that dislocations circumvent such particles by etruding between them, leaving a loop of dislocation around the particle. If we push many dislocations through the array of particles, as we need to do to achieve large plastic strains, we will rapidly produce a very large immobile dislocation density where the dislocations are loops around the particles. One would predict that the metal with hard particles would have a much larger strain hardening rate (higher) than the metal without particles. The eperiments (Fig. 18.4) show eactly the predicted behavior. 300 Shear Stress (MN/m ) % Shear Strain γ Figure 18.4 Strain hardening then is the hardening of the metal by immobile dislocation debris left as a result of plastic strain. In many pure metals it is the most important way to harden the material. On the other hand there are many instances where
4 -141- strain hardening is a nuisance or worse. For eample, in attempting to roll a bar of metal into a thin sheet the metal may become so hardened that cracks develop in the outside edges of the sheet. In such situations one would like to periodically soften the metal as the sheet is rolled thinner and thinner, i.e., one wants to remove the strain hardening. To do that it is necessary to remove the immobile dislocation debris. The primary way of removing the dislocation debris is by recrystallization. Recrystallization Not only can one remove the dislocation tangles built up in the course of strain hardening by the process of recrystallization but one also can use it to manipulate and control the grain size of the metal. The grain size is defined as the average diameter of the crystallites or "grains" in the polycrystal. One usually desires a small grain size. Small grained samples have higher yield stress σ y than large grained samples. In steels the ductile-to-brittle transition moves to lower temperatures (the steel becomes more ductile at room temperature) as the grain size is decreased. A large grain size leads to a large scale rumpling of the surface ("orange peel" effect) if the material is to undergo further plastic deformation during fabrication. Only for certain high temperature creep applications does one want a large grain size (in fact in these one would like a single crystal). Recrystallization takes place on annealing at elevated temperatures by the nucleation of new nearly dislocation-free grains in the dense dislocation tangles of the cell walls. The nuclei of these new grains are very small (often <100Å diameter) and the microscopic processes by which they form are not well understood. What is known is that they form in the densest parts of the dislocation tangles and that the driving force for their formation (nucleation) is the very high (local) strain energy in the dislocation tangle. [Remember the strain energy of a dislocation per unit length is ~Gb 2 (its line tension); if there is a high local ρ, there is a high local strain energy.] That strain energy is wiped out if a new dislocationfree grain is formed. It is known that the nuclei do not form by a melting and refreezing as implied by the word "recrystallization", but rather they form entirely in the solid state, for eample, by a shuffling of atoms across an eisting grain boundary. The number of nuclei formed per unit volume is directly proportional to the number of high strain energy (very dense) dislocation tangles per unit volume. In
5 -142- fact recrystallization will not take place at all until such dense tangles are formed. Thus a metal given no, or only a small plastic strain, will not recrystallize. It would not be possible to recrystallize the metal in Fig. 18.2a whereas in Fig. 18.2d where dense tangles are present recrystallization is possible. The fact that the number of new grain nuclei is proportional to the number of dense dislocation tangles is what allows us to control the final grain size of the metal after recrystallization is complete. After nucleation the new grains grow in size by migration outwards of the grain boundary surrounding the new grain. As the boundary moves outwards (actually by the shuffling of atoms across the grain boundary it destroys the high strain energy dislocation debris structure and replaces it with a low strain energy nearly dislocation-free material resulting from the grain boundary migration). After a certain time however, new grains growing from different nuclei eliminate all the old high dislocation density metal between them and impinge, forming a grain boundary between two strain free grains. When this impingement has occurred everywhere in the sample recrystallization is over. There is no more dislocation debris to cause either nucleation of new grains or migration of grain boundaries. (But see the process of grain growth, net lecture). Since each new grain nucleus ends up as a larger, strain free grain in the final recrystallized grain structure, the more nuclei we have to begin with, the smaller the size of the final grains will be. Thus if we want a large grain size we plastically deform to a strain where only a few very dense dislocation tangles have formed so that only a few new grains nucleate. The final recrystallized grain size will thus be very large. [It is even possible, but tedious, to grow a single crystal this way by knowing there is only one dislocation tangle in the entire sample capable of nucleating a new grain]. Conversely if one wants a very small grain size, one deforms to very high plastic strains where the number of dense dislocation tangles per unit volume is very high. The number of nuclei of new grains is very large and when they finally impinge, the grain size will be very small. Fig shows the recrystallized grain diameter vs. prior plastic strain for a brass. Notice that at low prestrains there is no recrystallization and one has the original grain structure of the metal. It is possible to produce grain sizes larger than or smaller than the original grain size by suitable plastic prestrain.
6 -143- Recrystallization grain si ze, mm Initial grain size, 0.5 mm Initial grain size, 0.05 mm % deformation, rolling Figure 18.5 After S. Channon and H. Walker, Trans. Am. Soc. Metals, 45, 200 (1953). Kinetics of Recrystallization From optical microscopy one can determine the percentage of the material that is recrystallized (that eists as new, rather than old, high dislocation density, grains.) Fig shows micrographs as various percentages of recrystallization. Figure 18.6 From: Nes and Ryum, Acta. Met (1975) The fraction recrystallized increases as a function of time at a given T as shown in Fig The process may take as much as 2 decades of time from start (nucleation) to finish (impingement) and the result is a characteristic sigmoidal (S shaped) curve. If one wanted to characterize the kinetics of the recrystallization by
7 -144- a single number one can use the time to 50% recrystallization, t 50%. Recrystallization (%) Incubation period { Time for 50% recrystallization Time of Annealing Figure 18.7 If we anneal at different temperatures we will find that the sigmoidal curve shifts to shorter times at higher temperatures as shown in Fig If we plot log t 50% from Fig vs. 1/T where T is the absolute temperature we find that the data are described by a straight line (Fig. 18.9). One can use that straight line relationship to etrapolate to conditions where eperiments are impractical. For eample one can use Figure 18.8 to predict that very pure copper will be 50% recrystallized at 24 F ( 3 C) in 25 years. Processes or mechanisms which give kinetic laws where log rate or log time varies as 1/T are said to be thermally activated. (Diffusion is another such process.) 275 F 235 F 191 F 109 F Recrystallization, % Time of Heating, min. Figure 18.8
8 F Temperature, F ,000 1,000,000 Time for 50% Recrystallization, mi n. 25 years Figure 18.9 Isothermal recrystallization of % pure copper. (After Decker and Harker.) One should mention that if one looks in handbooks (such as the Metals Handbook) one will find for various metals something called the "recrystallization temperature". Clearly from the eample above there is no such thing since if we wait long enough we can get recrystallization at almost any annealing temperature. However the Metals Handbook is designed for practical engineers and practical engineers do not like to anneal anything for much more than one hour. The recrystallization temperature T R is defined as the temperature at which T 50%, the time for 50% recrystallization, is one hour. For the eample of Cu used above, T R is about 240 F (116 C). A number of other material variables affect the recrystallization kinetics and thus the recrystallization temperature. Small amounts of trace impurities can drastically increase the T R since they slow down outward growth of the grain boundary surrounding the new dislocation-free grain. For eample T R for % Al (less than 1 part per million impurities) is 50 C whereas commercially pure Al (99% pure) has a T R of 250 C! The amount of prior plastic strain also affects the T R (can you think why?) giving rise to a decrease in T R with prior plastic strain as shown in Figure
9 T R ( F) % Al % Plastic Strain Figure Effects of the Amount of Cold Work on Kinetics - the greater the amount of cold work, the lower the T R on the lower t 50% at a given T. Just as strain hardening can produce large increases in the flow stress, recrystallization annuls these increases. Starting with a highly strain hardened metal (well-developed dislocation cell structure) the decreases in flow stress (or hardness) as a function of annealing temperature are shown schematically in Figure (Specimens are given a one hour anneal at each temperature before testing). There is a small decrease in flow stress below temperatures where recrystallization begins. This decrease is due to processes of dislocation rearrangement and a small amount of dislocation annihilation in the cell walls, processes which are called recovery processes. The major decrease in flow stress, to approimately its value before plastic deformation, occurs as a result of recrystallization. True Flow Stress σ t original flow stress before strain hardening recovery recrystallization begins T R microstructure is fully recrystallized Annealing Temperature Figure 18.11
CHAPTER 7 DISLOCATIONS AND STRENGTHENING MECHANISMS PROBLEM SOLUTIONS
7-1 CHAPTER 7 DISLOCATIONS AND STRENGTHENING MECHANISMS PROBLEM SOLUTIONS Basic Concepts of Dislocations Characteristics of Dislocations 7.1 The dislocation density is just the total dislocation length
More informationChapter Outline Dislocations and Strengthening Mechanisms
Chapter Outline Dislocations and Strengthening Mechanisms What is happening in material during plastic deformation? Dislocations and Plastic Deformation Motion of dislocations in response to stress Slip
More informationStrengthening. Mechanisms of strengthening in single-phase metals: grain-size reduction solid-solution alloying strain hardening
Strengthening The ability of a metal to deform depends on the ability of dislocations to move Restricting dislocation motion makes the material stronger Mechanisms of strengthening in single-phase metals:
More informationChapter Outline Dislocations and Strengthening Mechanisms
Chapter Outline Dislocations and Strengthening Mechanisms What is happening in material during plastic deformation? Dislocations and Plastic Deformation Motion of dislocations in response to stress Slip
More informationMechanical Properties of Metals Mechanical Properties refers to the behavior of material when external forces are applied
Mechanical Properties of Metals Mechanical Properties refers to the behavior of material when external forces are applied Stress and strain fracture or engineering point of view: allows to predict the
More informationModule #17. Work/Strain Hardening. READING LIST DIETER: Ch. 4, pp. 138-143; Ch. 6 in Dieter
Module #17 Work/Strain Hardening READING LIST DIETER: Ch. 4, pp. 138-143; Ch. 6 in Dieter D. Kuhlmann-Wilsdorf, Trans. AIME, v. 224 (1962) pp. 1047-1061 Work Hardening RECALL: During plastic deformation,
More informationConcepts of Stress and Strain
CHAPTER 6 MECHANICAL PROPERTIES OF METALS PROBLEM SOLUTIONS Concepts of Stress and Strain 6.4 A cylindrical specimen of a titanium alloy having an elastic modulus of 107 GPa (15.5 10 6 psi) and an original
More informationMSE 528 - PRECIPITATION HARDENING IN 7075 ALUMINUM ALLOY
MSE 528 - PRECIPITATION HARDENING IN 7075 ALUMINUM ALLOY Objective To study the time and temperature variations in the hardness and electrical conductivity of Al-Zn-Mg-Cu high strength alloy on isothermal
More informationx100 A o Percent cold work = %CW = A o A d Yield Stress Work Hardening Why? Cell Structures Pattern Formation
Work Hardening Dislocations interact with each other and assume configurations that restrict the movement of other dislocations. As the dislocation density increases there is an increase in the flow stress
More informationChapter Outline. Mechanical Properties of Metals How do metals respond to external loads?
Mechanical Properties of Metals How do metals respond to external loads? Stress and Strain Tension Compression Shear Torsion Elastic deformation Plastic Deformation Yield Strength Tensile Strength Ductility
More informationMaterials Issues in Fatigue and Fracture
Materials Issues in Fatigue and Fracture 5.1 Fundamental Concepts 5.2 Ensuring Infinite Life 5.3 Finite Life 5.4 Summary FCP 1 5.1 Fundamental Concepts Structural metals Process of fatigue A simple view
More informationChapter Outline: Phase Transformations in Metals
Chapter Outline: Phase Transformations in Metals Heat Treatment (time and temperature) Microstructure Mechanical Properties Kinetics of phase transformations Multiphase Transformations Phase transformations
More informationSolution for Homework #1
Solution for Homework #1 Chapter 2: Multiple Choice Questions (2.5, 2.6, 2.8, 2.11) 2.5 Which of the following bond types are classified as primary bonds (more than one)? (a) covalent bonding, (b) hydrogen
More informationDefects Introduction. Bonding + Structure + Defects. Properties
Defects Introduction Bonding + Structure + Defects Properties The processing determines the defects Composition Bonding type Structure of Crystalline Processing factors Defects Microstructure Types of
More informationDislocation theory. Subjects of interest
Chapter 5 Dislocation theory Subjects of interest Introduction/Objectives Observation of dislocation Burgers vector and the dislocation loop Dislocation in the FCC, HCP and BCC lattice Stress fields and
More informationChapter Outline. Diffusion - how do atoms move through solids?
Chapter Outline iffusion - how do atoms move through solids? iffusion mechanisms Vacancy diffusion Interstitial diffusion Impurities The mathematics of diffusion Steady-state diffusion (Fick s first law)
More informationSize effects. Lecture 6 OUTLINE
Size effects 1 MTX9100 Nanomaterials Lecture 6 OUTLINE -Why does size influence the material s properties? -How does size influence the material s performance? -Why are properties of nanoscale objects
More informationLösungen Übung Verformung
Lösungen Übung Verformung 1. (a) What is the meaning of T G? (b) To which materials does it apply? (c) What effect does it have on the toughness and on the stress- strain diagram? 2. Name the four main
More informationPROPERTIES OF MATERIALS
1 PROPERTIES OF MATERIALS 1.1 PROPERTIES OF MATERIALS Different materials possess different properties in varying degree and therefore behave in different ways under given conditions. These properties
More informationMaterial Deformations. Academic Resource Center
Material Deformations Academic Resource Center Agenda Origin of deformations Deformations & dislocations Dislocation motion Slip systems Stresses involved with deformation Deformation by twinning Origin
More informationIron-Carbon Phase Diagram (a review) see Callister Chapter 9
Iron-Carbon Phase Diagram (a review) see Callister Chapter 9 University of Tennessee, Dept. of Materials Science and Engineering 1 The Iron Iron Carbide (Fe Fe 3 C) Phase Diagram In their simplest form,
More informationNorth American Stainless
North American Stainless Long Products Stainless Steel Grade Sheet 2205 UNS S2205 EN 1.4462 2304 UNS S2304 EN 1.4362 INTRODUCTION Types 2205 and 2304 are duplex stainless steel grades with a microstructure,
More informationUNCLASSIFIED AD 404 5'18 DEFENSE DOCUMENIATION CENTER FO3 SCIENTIFIC AND TECHNICAL INFORMATION CAMERON STATIONH, ALEXANDRIA, V!RGINIA UNCLASSIF]HED
UNCLASSIFIED AD 404 5'18 DEFENSE DOCUMENIATION CENTER FO3 SCIENTIFIC AND TECHNICAL INFORMATION CAMERON STATIONH, ALEXANDRIA, V!RGINIA UNCLASSIF]HED NOTICE: When government or other drawings, specifications
More informationCH 6: Fatigue Failure Resulting from Variable Loading
CH 6: Fatigue Failure Resulting from Variable Loading Some machine elements are subjected to static loads and for such elements static failure theories are used to predict failure (yielding or fracture).
More informationLECTURE SUMMARY September 30th 2009
LECTURE SUMMARY September 30 th 2009 Key Lecture Topics Crystal Structures in Relation to Slip Systems Resolved Shear Stress Using a Stereographic Projection to Determine the Active Slip System Slip Planes
More informationLecture 14. Chapter 8-1
Lecture 14 Fatigue & Creep in Engineering Materials (Chapter 8) Chapter 8-1 Fatigue Fatigue = failure under applied cyclic stress. specimen compression on top bearing bearing motor counter flex coupling
More informationCrystal Defects p. 2. Point Defects: Vacancies. Department of Materials Science and Engineering University of Virginia. Lecturer: Leonid V.
Crystal Defects p. 1 A two-dimensional representation of a perfect single crystal with regular arrangement of atoms. But nothing is perfect, and structures of real materials can be better represented by
More informationLecture 19: Eutectoid Transformation in Steels: a typical case of Cellular
Lecture 19: Eutectoid Transformation in Steels: a typical case of Cellular Precipitation Today s topics Understanding of Cellular transformation (or precipitation): when applied to phase transformation
More informationLABORATORY EXPERIMENTS TESTING OF MATERIALS
LABORATORY EXPERIMENTS TESTING OF MATERIALS 1. TENSION TEST: INTRODUCTION & THEORY The tension test is the most commonly used method to evaluate the mechanical properties of metals. Its main objective
More informationThe atomic packing factor is defined as the ratio of sphere volume to the total unit cell volume, or APF = V S V C. = 2(sphere volume) = 2 = V C = 4R
3.5 Show that the atomic packing factor for BCC is 0.68. The atomic packing factor is defined as the ratio of sphere volume to the total unit cell volume, or APF = V S V C Since there are two spheres associated
More informationCONSOLIDATION AND HIGH STRAIN RATE MECHANICAL BEHAVIOR OF NANOCRYSTALLINE TANTALUM POWDER
CONSOLIDATION AND HIGH STRAIN RATE MECHANICAL BEHAVIOR OF NANOCRYSTALLINE TANTALUM POWDER Sang H. Yoo, T.S. Sudarshan, Krupa Sethuram Materials Modification Inc, 2929-P1 Eskridge Rd, Fairfax, VA, 22031
More informationIntroduction to microstructure
Introduction to microstructure 1.1 What is microstructure? When describing the structure of a material, we make a clear distinction between its crystal structure and its microstructure. The term crystal
More informationLecture slides on rolling By: Dr H N Dhakal Lecturer in Mechanical and Marine Engineering, School of Engineering, University of Plymouth
Lecture slides on rolling By: Dr H N Dhakal Lecturer in Mechanical and Marine Engineering, School of Engineering, University of Plymouth Bulk deformation forming (rolling) Rolling is the process of reducing
More informationME 612 Metal Forming and Theory of Plasticity. 1. Introduction
Metal Forming and Theory of Plasticity Yrd.Doç. e mail: azsenalp@gyte.edu.tr Makine Mühendisliği Bölümü Gebze Yüksek Teknoloji Enstitüsü In general, it is possible to evaluate metal forming operations
More informationFATIGUE CONSIDERATION IN DESIGN
FATIGUE CONSIDERATION IN DESIGN OBJECTIVES AND SCOPE In this module we will be discussing on design aspects related to fatigue failure, an important mode of failure in engineering components. Fatigue failure
More informationORIENTATION CHARACTERISTICS OF THE MICROSTRUCTURE OF MATERIALS
ORIENTATION CHARACTERISTICS OF THE MICROSTRUCTURE OF MATERIALS K. Sztwiertnia Polish Academy of Sciences, Institute of Metallurgy and Materials Science, 25 Reymonta St., 30-059 Krakow, Poland MMN 2009
More informationObjectives. Experimentally determine the yield strength, tensile strength, and modules of elasticity and ductility of given materials.
Lab 3 Tension Test Objectives Concepts Background Experimental Procedure Report Requirements Discussion Objectives Experimentally determine the yield strength, tensile strength, and modules of elasticity
More informationBending, Forming and Flexing Printed Circuits
Bending, Forming and Flexing Printed Circuits John Coonrod Rogers Corporation Introduction: In the printed circuit board industry there are generally two main types of circuit boards; there are rigid printed
More informationFluid Mechanics: Static s Kinematics Dynamics Fluid
Fluid Mechanics: Fluid mechanics may be defined as that branch of engineering science that deals with the behavior of fluid under the condition of rest and motion Fluid mechanics may be divided into three
More informationHEAT UNIT 1.1 KINETIC THEORY OF GASES. 1.1.1 Introduction. 1.1.2 Postulates of Kinetic Theory of Gases
UNIT HEAT. KINETIC THEORY OF GASES.. Introduction Molecules have a diameter of the order of Å and the distance between them in a gas is 0 Å while the interaction distance in solids is very small. R. Clausius
More informationFatigue of Metals Copper Alloys. Samuli Heikkinen 26.6.2003
Fatigue of Metals Copper Alloys Samuli Heikkinen 26.6.2003 T 70 C Temperature Profile of HDS Structure Stress amplitude 220 MPa Stress Profile of HDS Structure CLIC Number of Cycles f = 100 Hz 24 hours
More informationHeat Treatment of Steels : Spheroidize annealing. Heat Treatment of Steels : Normalizing
Heat Treatment of Steels :Recrystallization annealing The carbon and alloy steels were treated at a temperature of about 700 C, which is about 20 C below the eutectoid temperature. The holding time should
More informationThe Viscosity of Fluids
Experiment #11 The Viscosity of Fluids References: 1. Your first year physics textbook. 2. D. Tabor, Gases, Liquids and Solids: and Other States of Matter (Cambridge Press, 1991). 3. J.R. Van Wazer et
More informationWJM Technologies excellence in material joining
Girish P. Kelkar, Ph.D. (562) 743-7576 girish@welding-consultant.com www.welding-consultant.com Weld Cracks An Engineer s Worst Nightmare There are a variety of physical defects such as undercut, insufficient
More informationSTRAIN-LIFE (e -N) APPROACH
CYCLIC DEFORMATION & STRAIN-LIFE (e -N) APPROACH MONOTONIC TENSION TEST AND STRESS-STRAIN BEHAVIOR STRAIN-CONTROLLED TEST METHODS CYCLIC DEFORMATION AND STRESS-STRAIN BEHAVIOR STRAIN-BASED APPROACH TO
More informationEDEXCEL NATIONAL CERTIFICATE/DIPLOMA MECHANICAL PRINCIPLES OUTCOME 2 ENGINEERING COMPONENTS TUTORIAL 1 STRUCTURAL MEMBERS
ENGINEERING COMPONENTS EDEXCEL NATIONAL CERTIFICATE/DIPLOMA MECHANICAL PRINCIPLES OUTCOME ENGINEERING COMPONENTS TUTORIAL 1 STRUCTURAL MEMBERS Structural members: struts and ties; direct stress and strain,
More informationDIFFUSION IN SOLIDS. Materials often heat treated to improve properties. Atomic diffusion occurs during heat treatment
DIFFUSION IN SOLIDS WHY STUDY DIFFUSION? Materials often heat treated to improve properties Atomic diffusion occurs during heat treatment Depending on situation higher or lower diffusion rates desired
More informationObjective To conduct Charpy V-notch impact test and determine the ductile-brittle transition temperature of steels.
IMPACT TESTING Objective To conduct Charpy V-notch impact test and determine the ductile-brittle transition temperature of steels. Equipment Coolants Standard Charpy V-Notched Test specimens Impact tester
More informationTENSILE TESTING PRACTICAL
TENSILE TESTING PRACTICAL MTK 2B- Science Of Materials Ts epo Mputsoe 215024596 Summary Material have different properties all varying form mechanical to chemical properties. Taking special interest in
More informationMechanical Properties - Stresses & Strains
Mechanical Properties - Stresses & Strains Types of Deformation : Elasic Plastic Anelastic Elastic deformation is defined as instantaneous recoverable deformation Hooke's law : For tensile loading, σ =
More informationM n = (DP)m = (25,000)(104.14 g/mol) = 2.60! 10 6 g/mol
14.4 (a) Compute the repeat unit molecular weight of polystyrene. (b) Compute the number-average molecular weight for a polystyrene for which the degree of polymerization is 25,000. (a) The repeat unit
More informationLecture 12. Physical Vapor Deposition: Evaporation and Sputtering Reading: Chapter 12. ECE 6450 - Dr. Alan Doolittle
Lecture 12 Physical Vapor Deposition: Evaporation and Sputtering Reading: Chapter 12 Evaporation and Sputtering (Metalization) Evaporation For all devices, there is a need to go from semiconductor to metal.
More informationHeat Treatment of Steel
Heat Treatment of Steel Steels can be heat treated to produce a great variety of microstructures and properties. Generally, heat treatment uses phase transformation during heating and cooling to change
More informationThe stored energy of cold work: Predictions from discrete dislocation plasticity
Acta Materialia 53 (2005) 4765 4779 www.actamat-journals.com The stored energy of cold work: Predictions from discrete dislocation plasticity A.A. Benzerga a, *, Y. Bréchet b, A. Needleman c, E. Van der
More informationRAPIDLY SOLIDIFIED COPPER ALLOYS RIBBONS
Association of Metallurgical Engineers of Serbia AMES Scientific paper UDC:669.35-153.881-412.2=20 RAPIDLY SOLIDIFIED COPPER ALLOYS RIBBONS M. ŠULER 1, L. KOSEC 1, A. C. KNEISSL 2, M. BIZJAK 1, K. RAIĆ
More information14:635:407:02 Homework III Solutions
14:635:407:0 Homework III Solutions 4.1 Calculate the fraction of atom sites that are vacant for lead at its melting temperature of 37 C (600 K). Assume an energy for vacancy formation of 0.55 ev/atom.
More informationDesign MATERIAIS 9000 0 1960 History of Materials Science and Engineering http://www.crc4mse.org/what/mse_history.html FORÇAS TÉCNOLÓGICAS REVOLUCIONÁRIAS Têxtil Ferroviária Automotiva Computador
More informationThe Viscosity of Fluids
Experiment #11 The Viscosity of Fluids References: 1. Your first year physics textbook. 2. D. Tabor, Gases, Liquids and Solids: and Other States of Matter (Cambridge Press, 1991). 3. J.R. Van Wazer et
More informationNorth American Stainless
North American Stainless Flat Products Stainless Steel Sheet T409 INTRODUCTION NAS 409 is an 11% chromium, stabilized ferritic stainless steel. It is not as resistant to corrosion or high-temperature oxidation
More informationChapter 5: Diffusion. 5.1 Steady-State Diffusion
: Diffusion Diffusion: the movement of particles in a solid from an area of high concentration to an area of low concentration, resulting in the uniform distribution of the substance Diffusion is process
More informationMartensite in Steels
Materials Science & Metallurgy http://www.msm.cam.ac.uk/phase-trans/2002/martensite.html H. K. D. H. Bhadeshia Martensite in Steels The name martensite is after the German scientist Martens. It was used
More informationWeld Cracking. An Excerpt from The Fabricators' and Erectors' Guide to Welded Steel Construction. The James F. Lincoln Arc Welding Foundation
Weld Cracking An Excerpt from The Fabricators' and Erectors' Guide to Welded Steel Construction The James F. Lincoln Arc Welding Foundation Weld Cracking Several types of discontinuities may occur in welds
More informationTIE-31: Mechanical and thermal properties of optical glass
PAGE 1/10 1 Density The density of optical glass varies from 239 for N-BK10 to 603 for SF66 In most cases glasses with higher densities also have higher refractive indices (eg SF type glasses) The density
More informationUniaxial Tension and Compression Testing of Materials. Nikita Khlystov Daniel Lizardo Keisuke Matsushita Jennie Zheng
Uniaxial Tension and Compression Testing of Materials Nikita Khlystov Daniel Lizardo Keisuke Matsushita Jennie Zheng 3.032 Lab Report September 25, 2013 I. Introduction Understanding material mechanics
More information9. TIME DEPENDENT BEHAVIOUR: CYCLIC FATIGUE
9. TIME DEPENDENT BEHAVIOUR: CYCLIC FATIGUE A machine part or structure will, if improperly designed and subjected to a repeated reversal or removal of an applied load, fail at a stress much lower than
More informationMECHANICAL PRINCIPLES HNC/D PRELIMINARY LEVEL TUTORIAL 1 BASIC STUDIES OF STRESS AND STRAIN
MECHANICAL PRINCIPLES HNC/D PRELIMINARY LEVEL TUTORIAL 1 BASIC STUDIES O STRESS AND STRAIN This tutorial is essential for anyone studying the group of tutorials on beams. Essential pre-requisite knowledge
More informationLecture 9, Thermal Notes, 3.054
Lecture 9, Thermal Notes, 3.054 Thermal Properties of Foams Closed cell foams widely used for thermal insulation Only materials with lower conductivity are aerogels (tend to be brittle and weak) and vacuum
More informationENGINEERING COUNCIL CERTIFICATE LEVEL
ENGINEERING COUNCIL CERTIICATE LEVEL ENGINEERING SCIENCE C103 TUTORIAL - BASIC STUDIES O STRESS AND STRAIN You should judge your progress by completing the self assessment exercises. These may be sent
More informationEDEXCEL NATIONAL CERTIFICATE/DIPLOMA MECHANICAL PRINCIPLES AND APPLICATIONS NQF LEVEL 3 OUTCOME 1 - LOADING SYSTEMS TUTORIAL 3 LOADED COMPONENTS
EDEXCEL NATIONAL CERTIICATE/DIPLOMA MECHANICAL PRINCIPLES AND APPLICATIONS NQ LEVEL 3 OUTCOME 1 - LOADING SYSTEMS TUTORIAL 3 LOADED COMPONENTS 1. Be able to determine the effects of loading in static engineering
More informationCopper Alloys for Injection, Thermoform and Blow Molds
Copper Alloys for Injection, Thermoform and Blow Molds by Robert Kusner Manager of Technical Services June 2015 Today s Agenda History of copper mold alloys Why use copper? Which copper alloy should I
More informationCh. 4: Imperfections in Solids Part 1. Dr. Feras Fraige
Ch. 4: Imperfections in Solids Part 1 Dr. Feras Fraige Outline Defects in Solids 0D, Point defects vacancies Interstitials impurities, weight and atomic composition 1D, Dislocations edge screw 2D, Grain
More informationMassachusetts Institute of Technology Department of Mechanical Engineering Cambridge, MA 02139
Massachusetts Institute of Technology Department of Mechanical Engineering Cambridge, MA 02139 2.002 Mechanics and Materials II Spring 2004 Laboratory Module No. 5 Heat Treatment of Plain Carbon and Low
More informationProperties of Materials
CHAPTER 1 Properties of Materials INTRODUCTION Materials are the driving force behind the technological revolutions and are the key ingredients for manufacturing. Materials are everywhere around us, and
More informationThe mechanical properties of metal affected by heat treatment are:
Training Objective After watching this video and reviewing the printed material, the student/trainee will learn the basic concepts of the heat treating processes as they pertain to carbon and alloy steels.
More informationIntroduction to Materials Science, Chapter 9, Phase Diagrams. Phase Diagrams. University of Tennessee, Dept. of Materials Science and Engineering 1
Phase Diagrams University of Tennessee, Dept. of Materials Science and Engineering 1 Chapter Outline: Phase Diagrams Microstructure and Phase Transformations in Multicomponent Systems Definitions and basic
More informationEffects of Sulfur Level and Anisotropy of Sulfide Inclusions on Tensile, Impact, and Fatigue Properties of SAE 4140 Steel
Paper 28-1-434 Effects of Sulfur Level and Anisotropy of Sulfide Inclusions on Tensile, Impact, and Fatigue Properties of SAE 414 Steel Copyright 28 SAE International Nisha Cyril and Ali Fatemi The University
More informationFriction Surfacing of Austenitic Stainless Steel on Low Carbon Steel: Studies on the Effects of Traverse Speed
, June 30 - July 2, 2010, London, U.K. Friction Surfacing of Austenitic Stainless Steel on Low Carbon Steel: Studies on the Effects of Traverse Speed H. Khalid Rafi, G. D. Janaki Ram, G. Phanikumar and
More informationFATIGUE TESTS AND STRESS-LIFE (S-N) APPROACH
FATIGUE TESTS AND STRESS-LIFE (S-N) APPROACH FATIGUE TESTING LOADING TEST MACHINES SPECIMENS STANDARDS STRESS-LIFE APPEROACH S-N CURVES MEAN STRESS EFFECTS ON S-N BEHAVIOR FACTORS INFLUENCING S-N BEHAVIOR
More informationFundamentals of Extrusion
CHAPTER1 Fundamentals of Extrusion The first chapter of this book discusses the fundamentals of extrusion technology, including extrusion principles, processes, mechanics, and variables and their effects
More informationFree Electron Fermi Gas (Kittel Ch. 6)
Free Electron Fermi Gas (Kittel Ch. 6) Role of Electrons in Solids Electrons are responsible for binding of crystals -- they are the glue that hold the nuclei together Types of binding (see next slide)
More informationExperiment 1: Colligative Properties
Experiment 1: Colligative Properties Determination of the Molar Mass of a Compound by Freezing Point Depression. Objective: The objective of this experiment is to determine the molar mass of an unknown
More informationIntroduction To Materials Science FOR ENGINEERS, Ch. 5. Diffusion. MSE 201 Callister Chapter 5
Diffusion MSE 21 Callister Chapter 5 1 Goals: Diffusion - how do atoms move through solids? Fundamental concepts and language Diffusion mechanisms Vacancy diffusion Interstitial diffusion Impurities Diffusion
More informationHEAT TREATMENT OF STEEL
HEAT TREATMENT OF STEEL Heat Treatment of Steel Most heat treating operations begin with heating the alloy into the austenitic phase field to dissolve the carbide in the iron. Steel heat treating practice
More informationEFFECT OF SEVERE PLASTIC DEFORMATION ON STRUCTURE AND PROPERTIES OF AUSTENITIC AISI 316 GRADE STEEL
EFFECT OF SEVERE PLASTIC DEFORMATION ON STRUCTURE AND PROPERTIES OF AUSTENITIC AISI 316 GRADE STEEL Ladislav KANDER a, Miroslav GREGER b a MATERIÁLOVÝ A METALURGICKÝ VÝZKUM, s.r.o., Ostrava, Czech Republic,
More informationChapter Outline. How do atoms arrange themselves to form solids?
Chapter Outline How do atoms arrange themselves to form solids? Fundamental concepts and language Unit cells Crystal structures Simple cubic Face-centered cubic Body-centered cubic Hexagonal close-packed
More informationExperiment: Crystal Structure Analysis in Engineering Materials
Experiment: Crystal Structure Analysis in Engineering Materials Objective The purpose of this experiment is to introduce students to the use of X-ray diffraction techniques for investigating various types
More informationIn order to solve this problem it is first necessary to use Equation 5.5: x 2 Dt. = 1 erf. = 1.30, and x = 2 mm = 2 10-3 m. Thus,
5.3 (a) Compare interstitial and vacancy atomic mechanisms for diffusion. (b) Cite two reasons why interstitial diffusion is normally more rapid than vacancy diffusion. Solution (a) With vacancy diffusion,
More informationEnvironmental Stress Crack Resistance of Polyethylene Pipe Materials
Environmental Stress Crack Resistance of Polyethylene Pipe Materials ROBERT B. TAMPA, Product Development and Service Engineer* Abstract Slow crack growth is a phenomenon that can occur in most plastics.
More informationTensile Testing of Steel
C 265 Lab No. 2: Tensile Testing of Steel See web for typical report format including: TITL PAG, ABSTRACT, TABL OF CONTNTS, LIST OF TABL, LIST OF FIGURS 1.0 - INTRODUCTION See General Lab Report Format
More informationσ y ( ε f, σ f ) ( ε f
Typical stress-strain curves for mild steel and aluminum alloy from tensile tests L L( 1 + ε) A = --- A u u 0 1 E l mild steel fracture u ( ε f, f ) ( ε f, f ) ε 0 ε 0.2 = 0.002 aluminum alloy fracture
More informationTechnology of EHIS (stamping) applied to the automotive parts production
Laboratory of Applied Mathematics and Mechanics Technology of EHIS (stamping) applied to the automotive parts production Churilova Maria, Saint-Petersburg State Polytechnical University Department of Applied
More informationSheet metal operations - Bending and related processes
Sheet metal operations - Bending and related processes R. Chandramouli Associate Dean-Research SASTRA University, Thanjavur-613 401 Table of Contents 1.Quiz-Key... Error! Bookmark not defined. 1.Bending
More informationRadioactivity III: Measurement of Half Life.
PHY 192 Half Life 1 Radioactivity III: Measurement of Half Life. Introduction This experiment will once again use the apparatus of the first experiment, this time to measure radiation intensity as a function
More informationContinuous Cooling Bainite Transformation Characteristics of a Low Carbon Microalloyed Steel under the Simulated Welding Thermal Cycle Process
Available online at SciVerse ScienceDirect J. Mater. Sci. Technol., 2013, 29(5), 446e450 Continuous Cooling Bainite Transformation Characteristics of a Low Carbon Microalloyed Steel under the Simulated
More informationFEATURES AND BENEFITS OF DIFFERENT PLATINUM ALLOYS. Kris Vaithinathan and Richard Lanam Engelhard Corporation
FEATURES AND BENEFITS OF DIFFERENT PLATINUM ALLOYS Kris Vaithinathan and Richard Lanam Engelhard Corporation Introduction There has been a significant increase in the world wide use of platinum for jewelry
More informationMaterials Sciences. Dr.-Ing. Norbert Hort norbert.hort@gkss.de. International Masters Programme in Biomedical Engineering
Materials Sciences International Masters Programme in Biomedical Engineering Magnesium Innovations Center (MagIC) GKSS Forschungszentrum Geesthacht GmbH Dr.-Ing. Norbert Hort norbert.hort@gkss.de Contents
More informationModern Construction Materials Prof. Ravindra Gettu Department of Civil Engineering Indian Institute of Technology, Madras
Modern Construction Materials Prof. Ravindra Gettu Department of Civil Engineering Indian Institute of Technology, Madras Module - 2 Lecture - 2 Part 2 of 2 Review of Atomic Bonding II We will continue
More informationNorth American Stainless
Introduction: North American Stainless Flat Products Stainless Steel Grade Sheet 309S (S30908)/ EN1.4833 SS309 is a highly alloyed austenitic stainless steel used for its excellent oxidation resistance,
More informationLecture: 33. Solidification of Weld Metal
Lecture: 33 Solidification of Weld Metal This chapter presents common solidification mechanisms observed in weld metal and different modes of solidification. Influence of welding speed and heat input on
More informationKinetics of Phase Transformations: Nucleation & Growth
Kinetics of Phase Transformations: Nucleation & Growth Radhika Barua Department of Chemical Engineering Northeastern University Boston, MA USA Thermodynamics of Phase Transformation Northeastern University
More information