ENGINEERING MATERIALS AND METALLURGY AUTONOMOUS For fourth SEMESTER(II YEAR) PREPARED BY S.ARAVINDHA BALAJI ASSISTANT PROFESSOR DEPARTMENT OF MECHANICAL ENGINEERING SONA COLLEGE OF TECHNOLOGY SALEM:636005 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 SAB-AP/MECH SONACT Application of EMAM(In Industry): Steel industry( e.g. steel plants, (SAIL) Essar steels, jindal steel ltd.(JSW)) Pipe maufacturing industry, Plastic industry. Some jewelry industry(Grades of the gold) Manufacturing industry. 2 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 OBJECTIVE SAB-AP/MECH SONACT Knowledge on the structure Properties of the materials Treatment Testing and applications of metals and non-metallic materials Suitable materials for various engineering application 3 ENGINEERING MATERIALS AND METALLURGY Review (Not for Exam) Crystal structure BCC, (Body cubic centre) structure FCC, (Face cubic centre) structure and HCP, (Hexagonal close packing)structure Unit cell Crystallographic planes and directions Miller indices Crystal imperfections for point, line, planar and volume defects. ENGINEERING MATERIALS AND METALLURGY 1/5/2013 SAB-AP/MECH SONACT Review (Not for Exam) Grain size ASTM grain size number 5 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Constitution of alloys-Solid solution, substitutional and interstitial-Phase diagrams, Isomorphous, eutectic, peritectic, and peritectroid reactions, Iron-Iron carbon equilibrium diagram. of steel and cast Iron, Microstructure, Properties and applications. SAB-AP/MECH SONACT Classification 6 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 UNIT:II HEAT TREATMENT SAB-AP/MECH SONACT Definition-Full annealing, stress relief, recrystallisation and spheroidizingnormalising, hardening and tempering of steel. Isothermal transformation diagrams-cooling curves superimposed on I.T.diagram, CCR-Hardenability, Jominy and quench testAustempering, Martempering-case hardeningcarburising, nitriding, cyaniding, carbonitriding, flame and induction hardening . 7 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 SAB-AP/MECH SONACT UNIT:III MECHANICAL PROPERTIES AND TESTING Mechanism of plastic deformation, slip and twinning-types of fracture-testing of materials under tension, compression and shear loadsHardness tests (Brinell, Vickers and Rockwell), Impact test-Izod and charpy, Fatigue and creep tests, fracture toughness tests. 8 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 UNIT:IV FERROUS AND NON FERROUS METALS SAB-AP/MECH SONACT Effect of alloying elements on steel(Mn, Si, Cr, Mo, V, Ti & W) –Stainless and tool steels –HSLA-maraging steels-Cast irons-Grey, White malleable, spheroidal-Graphite, Alloy cast irons, Copper and copper alloys-Brass, Bronze and Cupronickel-Aluminum and Al-Cu alloyPrecipitation hardening-Bearing alloys. 9 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 SAB-AP/MECH SONACT UNIT V NON-METALLIC MATERIALS Polymers-Types of polymer, commodity and Engineering polymers-properties and applications of PE, PP, PS, PVC, PMMA, PET, PC, PA, ABS, PI, PAI, PPO, PPS, PEEK, PTFE Polymer-Urea and Phenol formaldehydesEngineering ceramics-Introduction to fiber reinforced plastics. 10 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 Each category of engineering application requires material from any or all of these three group of materials Ceramics and glasses Polymers Engineering Materials SAB-AP/MECH SONACT Metals and alloys Application Structures Machines Devices 11 Ceramic and glasses Mgo, cds, Al2O3, S iC, BaTio3,Silica, soda-time-glass, Concrete, cement ferrites and garnets ceramic superconductors Organic polymers Plastics, Pvc,PTFE, polyethylene SAB-AP/MECH SONACT Metals and alloys Steels, aluminum, copper, silver ,gold, Brasses,, bronze s, maganin invar, super alloys boron rare earth magnetic alloys Metalreinforce d plastics Si, Ge, GaAs, Boridereinforced steel ENGINEERING MATERIALS AND METALLURGY Fibers:Terylene,nylo n,cotton, natural, and synthetic rubbers , leathers Glass fiber- reinforced plastics 1/5/2013 12 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 SAB-AP/MECH SONACT Structure: The internal structure of a material, simply called the structure. 13 NON-METALLIC MATERIALS: SAB-AP/MECH SONACT PE (polyethylene) PP (Polypropylene) PS(Polystyrene) PMMA(Polymethyl methacrylate) PET(Polyethylene teraphthalate) PC(Polycarbonates) PA(Polyamides) ABS(Acryknitrile-Butadiene-styrene) PI(Polyimide) 1/5/2013 14 NON-METALLIC MATERIALS: SAB-AP/MECH SONACT PAI( Polyamideimide) PPO(Polyphenylene oxide) PPS(Polyphenylene sulphide) PEEK(Polyether ether ketone) PTFE(Polytetra fluoro ethylene) 1/5/2013 15 ENGINEERING MATERIALS AND METALLURGY 1/5/2013 SAB-AP/MECH SONACT UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Constitution of alloys-Solid solution, substitutional and interstitial-Phase diagrams Isomorphous, eutectic, peritectic, and peritectroid reactions, Iron-Iron carbon equilibrium diagram. Classification of steel and cast Iron, Microstructure, Properties and applications. 16 CONSTITUTION- establishment, foundation, creation, formation, structure, organization, charter, bill. SAB-AP/MECH SONACT 1/5/2013 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS 17 1.SYSTEM: It is a combination of phases of one or more components. SAB-AP/MECH SONACT SOME TECHNICAL TERMS AND DEFINITIONS: 1/5/2013 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS 2.PHASE: It is a Physically and chemically homogenous part of a system under study, one phase is different from the other in structure or composition 18 3.COMPONENTS: system are called component. A system may consist of two or more components. SAB-AP/MECH SONACT The elements present in the 1/5/2013 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS 19 CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS An alloy is defined as a combination of two or more elements, of which one of the element should be a metal in major proportion. SAB-AP/MECH SONACT 1/5/2013 CONSTITUTION OF ALLOYS: 4.ALLOY: The others could be metals or non-metals, for eg: Brass (CU-Zn), Steel (Fe-C) 20 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Uses of pure metals 1. High electrical conductivity 2. High ductility SAB-AP/MECH SONACT Alloy find very wide application in the industry than pure metals. 1/5/2013 3. Corrosion resistance are required. These properties are generally at a maximum value in pure metals. 21 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Mechanical properties 2. Yield point SAB-AP/MECH SONACT 1. Tensile strength 1/5/2013 3. Hardness are improved by alloying. 22 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Pure metals Solid Solution SAB-AP/MECH SONACT CLASSIFICATION OF ALLOYS 1/5/2013 CLASSIFICATION OF ALLOYS Intermedia te phase 23 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Alloy can be either a single phase or a mixture A phases is anything which is homogeneous and SAB-AP/MECH SONACT of phases. 1/5/2013 physically distinct. In solid state alloys of three are three possible phase. 24 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS If an alloy has a single phase, it could be either If the alloy is a mixture it could be composed of any combination of the above three phases. SAB-AP/MECH SONACT a solid solution or an intermediate phase. 1/5/2013 25 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS SAB-AP/MECH SONACT major element which is large in amount is called base metal or parent metal or solvent. The other element that is lesser in amount is called the alloying element or solute, it is the minor part (such as salt or sugar which is less in amount, being mixed in water- solvent). 1/5/2013 The 26 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS 1/5/2013 SAB-AP/MECH SONACT 5. MIXTURE: It is a material more than one phase. 27 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Disordered (or) Random Ordered (or) regular Interstitial solid solution SAB-AP/MECH SONACT Substitutinal Solid solution 1/5/2013 SOLID SOLUTION 28 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS A solid solution is the simplest type of alloys. A Solution can be defined as a homogeneous mixture in which the atoms or molecules of one substance are SAB-AP/MECH SONACT solutions: 1/5/2013 Solid dispersed at random into another substance. 29 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS SAB-AP/MECH SONACT 1 . Solute: A solute is the minor part of the solution or the material which is dissolved. 1/5/2013 A solid solution may be defined as a solid that consist of two or more elements atomically dispersed in a single-phase structure. A solid solution is composed of two parts. 30 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Both the solute and the solvent can be solid, SAB-AP/MECH SONACT the solution. 1/5/2013 2. Solvent: Solvent constitutes the major portion of liquid or gas. 31 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS Solid solution: Solid solution may be defined as a solution In the solid state which consists of two kinds of atoms combined in one type of space SAB-AP/MECH SONACT Simply a solution in the solid state. 1/5/2013 lattice. 32 UNIT:I CONSTITUTION OF ALLOYS AND PHASE DIAGRAMS space lattice: points in three dimensions in which every point has surroundings identical to that every other SAB-AP/MECH SONACT Space lattice is defined as an array of 1/5/2013 point in the array. 33 SOLID SOLUTION In certain cases, the solidification of an alloy results in the formation of one kind of crystal. In which both metals are present, but they cannot be detected by the microscope Although properties of the crystals are profoundly( deeply,strongly) changed. SAB-AP/MECH SONACT Case: 1/5/2013 34 SOLID SOLUTION In such a case we have a solid metal in which the has been persevered after solidification, and it is known as a solid solution. SAB-AP/MECH SONACT interatomic state which existed in the liquid solution 1/5/2013 In a solid solution the atom occur in a definite geometrical pattern, which is usually a slightly distorted form of one of the constituent metals. 35 SOLID SOLUTION 1/5/2013 SAB-AP/MECH SONACT Soildsolution are conductors, but not so good as the pure metals on which they are based. Some examples of solid solutions are: Cu-Zn alloys (Brasses) Ni-Cu alloys (Monel metal) Au-Ag alloys(Sterling silver) Fe-Cr-Ni alloys (Certain stainless steels) Fe-C alloys (Steels) 36 SUBSTITUTIONAL SOLID SOLUTION solute-Atom of Metal-B Solvent-Atoms of zinc Metal-A zinc(Solute) Copper(Solvent) Disordered substitutinal solid solution(random,) SAB-AP/MECH SONACT SOLVENT OR MATRIX ATOMS 1/5/2013 Solute Atoms 37 SUBSTITUTIONAL SOLID SOLUTION Ordered subsitutional solid solution Solute Atoms SAB-AP/MECH SONACT SOLVENT OR MATRIX ATOMS 1/5/2013 38 SUBSTITUTIONAL SOLID SOLUTION In substitutional solid solution, there is a direct so that solute atoms(cu) enter the crystal to take positions normally occupied by solvent atoms (e.g., SAB-AP/MECH SONACT substitution of one type of atom for another. 1/5/2013 Nickel atoms); 39 SUBSTITUTIONAL SOLID SOLUTION The alloy is said to be in a disordered condition if solution, the solute atoms do not occupy any specific position but are distributed at random in SAB-AP/MECH SONACT in the formation of a substitutional solid 1/5/2013 the lattice structure of the solvent. 40 SUBSTITUTIONAL SOLID SOLUTION An ordered subsititutional solid solution is shown ordered structures. SAB-AP/MECH SONACT fig Cu-Zn, Al-Cu, α-Brass are some examples of 1/5/2013 41 INTERSTITIAL SOLID SOLUTION The four elements hydrogen, carbon, nitrogen, can occupy the empty spaces (Interstices) in the crystal lattices of many metals. SAB-AP/MECH SONACT and boron have such small diameters that they 1/5/2013 42 INTERSTITIAL SOLID SOLUTION Solute atoms (solute) SAB-AP/MECH SONACT CARBON 1/5/2013 Solvent or matrix atoms IRON ( SOLVENT) INTERSTITIAL SOLID SOLUTION 43 INTERSTITIAL SOLID SOLUTION Interstitial solid solution usually have a limited of secondary importance, but there are a few instances worthy of special attention. SAB-AP/MECH SONACT composition range and are generally considered 1/5/2013 44 INTERSTITIAL SOLID SOLUTION The interstitial solution of carbon in iron Very small amount of hydrogen introduced into SAB-AP/MECH SONACT constitutes the basis of steel hardening. 1/5/2013 steels during acid pickling(cleaning), plating, or welding operations causes a Sharpe decrease in ductility, known as hydrogen embrittlement. 45 INTERSTITIAL SOLID SOLUTION Interstitial nitrogen is useful not only in in maintaining 18Cr-8Ni SAB-AP/MECH SONACT nirtriding process but also as an important factor 1/5/2013 Stainless steel in the austenitic condition. 46 HUME - ROTHERY’S RULES OF SOLID SOLUBILITY 1/5/2013 SAB-AP/MECH SONACT Hume - Rothery’s Rules of solid solubility 47 HUME - ROTHERY’S RULES OF SOLID SOLUBILITY 1/5/2013 SAB-AP/MECH SONACT Hume - Rothery’s Rules of solid solubility 48 INTERSTITIAL SOLID SOLUTION various factors. These were stated by Hume-rothery and are as follows: 1. SAB-AP/MECH SONACT The solubility limit of solute in solvents depends on 1/5/2013 HUME –ROTHERY’S RULES OF SOLID SOLUBILITY Critical structure factor (or) Crystal structure: Metals that have the same crystal stucture (Lattice structure) have a greater solubility. 49 INTERSTITIAL SOLID SOLUTION difference in size of solute and solvent is less than 15%. If the difference is greater than 15% formation of SAB-AP/MECH SONACT The solid solution will tend to form if the 1/5/2013 2. Relative atomic size factor(or) size factor: solid solution will be limited. For good solid solubility the difference should be less than 8% 50 INTERSTITIAL SOLID SOLUTION favoured for metals that have less chemical affinity is more, then a compound is formed instead of a solid solution. SAB-AP/MECH SONACT Formulation of solid solution is 1/5/2013 3. Chemical affinity factor (or) Electronegativity: The metal which are separated in widely in the periodic table are not suitable for making alloys because of their high affinity. 51 INTERSTITIAL SOLID SOLUTION disslove only a small amount of a lower valency metal, where as the metal with low valency SAB-AP/MECH SONACT A metal that has a higher valency will 1/5/2013 4. Relative valency factor(or)valence: will have good solubility for the higher valency metal. 52 INTERSTITIAL SOLID SOLUTION In some alloys both interstitial and appreciable extent. SAB-AP/MECH SONACT substitutional solid solution are formed to an 1/5/2013 For Eg: A Cr-Ni steel contains interstitially dissolved carbon and substitution ally dissolved chromium, nickel, and minor elements. 53 POSSIBILITIES OF SOLID SOLUTIONS There are three possible solid solutions based on 1.Unsaturated solid solution: In the solvent is SAB-AP/MECH SONACT the amount of their elements. They are: 1/5/2013 • dissolving small amount of solute as well as at a given temperature and pressure, it is called unsaturated solid solution. 54 POSSIBILITIES OF SOLID SOLUTIONS limiting amount of solute, it is called saturated solid solution. SAB-AP/MECH SONACT If the solvent is dissolving 1/5/2013 2. Saturated solid solution: 55 POSSIBILITIES OF SOLID SOLUTIONS should, under equilibrium, it is called supersaturated solid solution. SAB-AP/MECH SONACT If the solvent is dissolving more of solute that it 1/5/2013 3. Supersaturated solid solution: 56 PHASE DIAGRAM 2. Eutectoid system SAB-AP/MECH SONACT 1. Isomorphous 1/5/2013 Types of phase diagram 3. Eutectic system 4.Peritectic system 5. Peritectroid reactions 57 PHASE DIAGRAM Phase Diagrams representation of what phases are present in an SAB-AP/MECH SONACT Phase diagrams are graphical 1/5/2013 alloy system at various Temperatures, pressures, and compositions. 58 PHASE DIAGRAM Phase diagrams are also known as equilibrium SAB-AP/MECH SONACT A phase diagram is a map showing the structure or phase present as the temperature and overall composition of the material are varied. 1/5/2013 (or) diagrams or constitutional diagrams. 59 WHY SHOULD PHASE DIAGRAMS BE STUDIED? The phase diagrams can answer the following What condition is the material in? Is the composition uniform throughout? SAB-AP/MECH SONACT important questions: 1/5/2013 If not, how much of each component is present? 60 WHY SHOULD PHASE DIAGRAMS BE STUDIED? Is something present that may give undesired What will happen if temperature is increased or SAB-AP/MECH SONACT properties? 1/5/2013 decreased; pressure is changed or composition is varied? 61 WHY SHOULD PHASE DIAGRAMS BE STUDIED? Phase diagrams are used by engineers and aspects of the behavior of materials. SAB-AP/MECH SONACT scientists to understand and to predict many 1/5/2013 62 TERMINOLOGY USED IN PHASE DIAGRAMS Components System 3. Alloy 4. Solid solution 5. Solute Solution SAB-AP/MECH SONACT 2. 1/5/2013 1. 63 TERMINOLOGY USED IN PHASE DIAGRAMS 8. Equilibrium SAB-AP/MECH SONACT 7. Phase 1/5/2013 6. Solvent 9. Solubility limit 10.Degrees of freedom 64 TERMINOLOGY USED IN PHASE DIAGRAMS The various terms used in the study of phase 1. COMPONENT: Component are pure metals SAB-AP/MECH SONACT diagrams have been explained below: 1/5/2013 and or compounds of which an alloy is composed. Eg: In a copper-zinc brass, the components are CU and Zn. 65 TERMINOLOGY USED IN PHASE DIAGRAMS i. System: May refer to a specific body of material under consideration. For Eg: A SAB-AP/MECH SONACT context 1/5/2013 2. SYSTEM: The system has two meanings in this ladle of molten steel is referred as a system. 66 TERMINOLOGY USED IN PHASE DIAGRAMS (ii)system: May also refer to the series of possible example, the Iron-Carbon system. SAB-AP/MECH SONACT alloys consisting of the same components. For 1/5/2013 67 TERMINOLOGY USED IN PHASE DIAGRAMS A system having one components is called a and four components are known as Binary, ternary and quaternary systems, respectively. SAB-AP/MECH SONACT Unary system, and the system having two, three 1/5/2013 68 TERMINOLOGY USED IN PHASE DIAGRAMS or a metal (metals) and a non-metal (non-metals). SAB-AP/MECH SONACT An alloy is a mixture of two or more metals 1/5/2013 3. ALLOY: 69 TERMINOLOGY USED IN PHASE DIAGRAMS more elements atomically dispersed in a singlephase structure. SAB-AP/MECH SONACT It is a solid that consist of two or 1/5/2013 4.SOLID SOLUTION: 70 TERMINOLOGY USED IN PHASE DIAGRAMS solution or the material which is dissolved. SAB-AP/MECH SONACT It is the minor part of the 1/5/2013 5. SOLUTE SOLUTION: 71 TERMINOLOGY USED IN PHASE DIAGRAMS major portion of the solution. SAB-AP/MECH SONACT The material which contributes the 1/5/2013 6. SOLVENT: 72 TERMINOLOGY USED IN PHASE DIAGRAMS portion of a system that has uniform physical SAB-AP/MECH SONACT A phase may be defined as a homogenous 1/5/2013 7. PHASE: and chemical characteristics. 73 TERMINOLOGY USED IN PHASE DIAGRAMS enough time is allowed for all possible reactions SAB-AP/MECH SONACT Equilibrium is said to exit when 1/5/2013 8. EQUILIBRIUM: to be completed. 74 TERMINOLOGY USED IN PHASE DIAGRAMS The equilibrium state refers to the constant indefinitely. Equilibrium occurs when SAB-AP/MECH SONACT characteristics of the system that remain 1/5/2013 the free energy of the system is at its minimum value. 75 TERMINOLOGY USED IN PHASE DIAGRAMS The term phase equilibrium refers to more than one phase may exist. SAB-AP/MECH SONACT equilibrium as it applies to systems in which 1/5/2013 76 TERMINOLOGY USED IN PHASE DIAGRAMS solute that may be added without forming a new phase. SAB-AP/MECH SONACT It is the maximum concentration of 1/5/2013 9. SOLUBILITY LIMIT: 77 TERMINOLOGY USED IN PHASE DIAGRAMS NOTE: The addition of solution in excess another solid solution or compound. SAB-AP/MECH SONACT of the solubility limit results in the formation of 1/5/2013 78 TERMINOLOGY USED IN PHASE DIAGRAMS independent variables ( such as temperature, pressure, and composition). SAB-AP/MECH SONACT It is the number of 1/5/2013 10. DEGREES OF FREEDOM: That can be changed independently without changing the phase or phases of the system. 79 WHAT IS MEANT BY THE TERM PHASE? A phase may be a portion of matter which is A phase may be defined as any physical distinct SAB-AP/MECH SONACT homogenous 1/5/2013 homogenous and mechanically separable portion of a substance. 80 WHAT IS MEANT BY THE TERM PHASE? In Layman’s term, a phase requires a unique boundaries or interfaces SAB-AP/MECH SONACT structure, uniform composition, and well-defined 1/5/2013 Examples: A pure substance such as water is a single phase. 81 WHAT IS MEANT BY THE TERM PHASE? The pure substance water can exist in solid, single phase, as shown in fig (a) SAB-AP/MECH SONACT liquid and vapour, each of these states being a 1/5/2013 Now consider the effect of adding salt(Nacl) to water. Salt will dissolve in water to give a homogeneous solution. 82 WHAT IS MEANT BY THE TERM PHASE? Thus the salt- water solution forms a single If more salt is added into water, then we have SAB-AP/MECH SONACT phase as shown if fig(b) 1/5/2013 two different phases as shown if fig(c) 83 WHAT IS MEANT BY THE TERM PHASE? A Single phase system is also termed as SAB-AP/MECH SONACT “homogeneous system” 1/5/2013 84 WHAT IS MEANT BY THE TERM PHASE? System composed of two or more phases are Fig (d) SAB-AP/MECH SONACT termed as mixtures or heterogeneous systems’. 1/5/2013 Most metallic alloys, ceramic, polymers, and composite are heterogenous. 85 ILLUSTRATION OF PHASES WATER(2) SAB-AP/MECH SONACT ICE (1) 1/5/2013 WATER VAPOUR(3) WATER ILLUSTRATION OF PHASES: (A) Three forms of water: 1) Ice 2)water 3) 86 water vapour are each a phase. ILLUSTRATION OF PHASES 1/5/2013 salt SAB-AP/MECH SONACT • (b) Salt and water have unlimited solubility (Homogeneous solution)- from a single phase 87 ILLUSTRATION OF PHASES 1/5/2013 Saturated brine SAB-AP/MECH SONACT Excess salt (C) Salt and water have limited solubility (Heterogenous solution)-from two distinct phases 88 ILLUSTRATION OF PHASES 1/5/2013 SAB-AP/MECH SONACT OIL WATER OIL AND WATER HAVE VIRTUALLY NO SOLUBILITY FROM TWO DISTINCT PHASES 89 PHASE DIAGRAM OF PURE SUBSTANCE One- Component Phase diagram 1/5/2013 SAB-AP/MECH SONACT 90 PHASE DIAGRAM OF PURE SUBSTANCE 1/5/2013 SAB-AP/MECH SONACT 91 PHASE DIAGRAM OF PURE SUBSTANCE A pure substance such as water can exist in condition of temperature and pressure SAB-AP/MECH SONACT solid, liquid, or vapour phases, depending on the 1/5/2013 92 PHASE DIAGRAM OF PURE SUBSTANCE The phase relationships may be represented on a one-component (or unary) phase diagram, for the H2O System. SAB-AP/MECH SONACT a pressure- temperature (PT) diagram, known as 1/5/2013 93 PHASE DIAGRAM OF PURE SUBSTANCE The phase diagram is composed of regions of phase is stable. SAB-AP/MECH SONACT pressure and temperature where only a single 1/5/2013 The line OA indicates the vapourisation line and the line OB indicates the freezing line. 94 PHASE DIAGRAM OF PURE SUBSTANCE Liquid and vapour phase exist along the along the freezing line, shows in figure. These lines are also known as Two phase equilibrium SAB-AP/MECH SONACT vapourisation line and liquid and solid phases 1/5/2013 lines. 95 PHASE DIAGRAM OF PURE SUBSTANCE The point “O” is know as Triple point. (Solid, liquid, and vapour phases(gas)). SAB-AP/MECH SONACT Triple point is the point at which three phases 1/5/2013 of a single material coexit. This triple point of water exists at temperature 0.00980C and at pressure 4.58 mm of Hg. 96 PHASE DIAGRAMS The properties of an alloy depend on nature, phases. SAB-AP/MECH SONACT amount, size, distribution and orientation of the 1/5/2013 A phase is the chemically and structurally homogeneous portion of the microstructure. 97 PHASE DIAGRAMS It has the following characteristics 2. Roughly the same composition and properties throughout. SAB-AP/MECH SONACT 1. Same structure throughout. 1/5/2013 3. Definite interface between the phase and surrounding. 98 1/5/2013 J.W. GIBBS ( JOSIAH WILLARD GIBBS) SAB-AP/MECH SONACT 99 J.W. GIBBS( JOSIAH WILLARD GIBBS) (OR) (OR) GIBB’S PHASE RULE (or) SAB-AP/MECH SONACT J.W. GIBBS LAW 1/5/2013 JOSIAH WILLARD GIBBS PROPOSAL PHASE RULE 100 GIBBS PHASE RULE J.W. Gibbs, American physicist derived an system between the number of phases, SAB-AP/MECH SONACT equation which established relationship in a 1/5/2013 The number of degree of freedom and the number of components. 101 GIBB’S PHASE RULE The phase rule indicates the phases that exists The Gibb’s phase rule satisfies the following relation: SAB-AP/MECH SONACT at equilibrium. 1/5/2013 P+F=C+n 102 GIBB’S PHASE RULE P- Number of phases that exist in a C-Number of components in the system. SAB-AP/MECH SONACT system under certain conditions. 1/5/2013 n- It represents the number of variables, examples: Temperature, pressure and concentration. 103 GIBB’S PHASE RULE pressure or concentration which can be change independently without SAB-AP/MECH SONACT variables such as temperature or 1/5/2013 F- Degree of freedom. It is the number of changing the number of phases that are present in the system. 104 GIBB’S PHASE RULE i.e., 1 atmospheric pressure and hence pressure is not considered a variable. Usually the only variable under consideration is temperature and hence the Gibb’s phase rule becomes; SAB-AP/MECH SONACT In most studies the pressure is constant 1/5/2013 P+F=C+1 105 USES OF PHASE RULE The phase rule predicts maximum number of conditions at any point of diagram. If the number of phases are known, one can determine the degree of freedom using phase SAB-AP/MECH SONACT phases present in the alloy under equilibrium 1/5/2013 rule. 106 USES OF PHASE RULE Thus the phase rule is useful to know whether can be changed without changing the structure of the alloy. SAB-AP/MECH SONACT the temperature or pressure or both variables 1/5/2013 107 ILLUSTRATION OF THE USE OF THE PHASE RULE Let us consider the application of gibbs phase rule Case 1 : Consider a triple point in the diagram. At the triple point, three phases coexist in equilibrium . SAB-AP/MECH SONACT to the phase diagram of water system 1/5/2013 P=3. Since there is one component (water) in the system C= 1 108 THE USE OF THE PHASE RULE The number of degree of freedom can be F=1- 3+2 F=0 (Zero degree of freedom) SAB-AP/MECH SONACT calculated using the Gibbs phase rule as, 1/5/2013 This means that one of the variables (Temperature or pressure) can be changed at the triple point. 109 THE USE OF THE PHASE RULE Note: Since the variables temperature or three phases of coexistence. SAB-AP/MECH SONACT pressure cannot be changed and still keep the 1/5/2013 The triple point is called an invariant point. 110 THE USE OF THE PHASE RULE liquid- 1/5/2013 SAB-AP/MECH SONACT Case 2: Next consider a point along solid freezing curve P=2 Then for water system C=1 Applying the phase rule, we get: F=1- 2+ 2 F=1 (one degree of freedom) 111 THE USE OF THE PHASE RULE ( Temperature or pressure) can be changed independently and still maintain a system SAB-AP/MECH SONACT This means that one variable 1/5/2013 with two coexisting phases. 112 THE USE OF THE PHASE RULE Case:3 SAB-AP/MECH SONACT Now consider a point on the phase diagram of water inside a single phase in this case there will be only one phase present. P=1 , Then for water system, C=1 Now the phase rule gives 1/5/2013 113 THE USE OF THE PHASE RULE F=1-1+2 This means that two variables ( Temperature and pressure) can be varied independently and SAB-AP/MECH SONACT F=2 ( two degree of freedom) 1/5/2013 the system will still remain in a single phase. 114 THE USE OF THE PHASE RULE Note: In many application (especially for most atmosphere. In this case Gibbs phase rule is modified as SAB-AP/MECH SONACT binary alloy) the pressure is kept constant at 1 1/5/2013 F=C-P+1 115 THE USE OF THE PHASE RULE The above equation is known as condensed phase This equation can be applied to most of SAB-AP/MECH SONACT rule. 1/5/2013 the binary phase diagram. 116 OBJECTIVE TYPE QUESTIONS of a small group of atoms oriented into one of the common crystal patterns. SAB-AP/MECH SONACT centre of freezing, or nucleus, which is composed 1/5/2013 1. -----------May be visualized as forming from a Crystal 117 OBJECTIVE TYPE QUESTIONS conditions SAB-AP/MECH SONACT obtained only if crystallisation develops under 1/5/2013 2.Perfect crystal of proper external shape can be when degree of ----------------is very slight and the metal has a very high purity. 118 MICRO-CONSTITUENTS OF IRON-CARBON ALLOYS There are different micorscope constituents of The study of these micro-constituents is SAB-AP/MECH SONACT Iron-Carbon alloys exit. 1/5/2013 essential in order to understand iron-iron carbide (Fe-Fe3C) equilibrium phase diagram. 119 VARIOUS MICRO-CONSTITUENTS OF IRONCARBON ALLOYS ARE: 3.Cementite SAB-AP/MECH SONACT 2.Austenite 1/5/2013 1.Ferrite 4.Pearlite 5.Ledeburite 6.Martensite 120 VARIOUS MICRO-CONSTITUENTS OF IRONCARBON ALLOYS ARE: 9.Bainite SAB-AP/MECH SONACT 8. Sorbite, and 1/5/2013 7. Troosite 121 VARIOUS MICRO-CONSTITUENTS OF IRONCARBON ALLOYS ARE: Ferrite is a primary solid solution based on α iron having BCC structure. SAB-AP/MECH SONACT Ferrite (or α-Iron) 1/5/2013 1. It is Nothing but the interstitial solid solution of carbon in iron. 122 FERRITE 1/5/2013 SAB-AP/MECH SONACT 123 VARIOUS MICRO-CONSTITUENTS OF IRONCARBON ALLOYS ARE: Maximum solubility of carbon in iron is 0.025% carbon only 0.008%. SAB-AP/MECH SONACT at 723°C, While its solubility at room temperature is 1/5/2013 Ferrite is soft, ductile, and highly Magnetic. It can undergo extensive cold working 124 VARIOUS MICRO-CONSTITUENTS OF IRONCARBON ALLOYS ARE: Austenite is a primary solid solution based on γ iron having FCC structure. SAB-AP/MECH SONACT 1/5/2013 2. Austenite(or γ-Iron) This is also an interstitial solid solution of carbon in iron 125 AUSTENITE 1/5/2013 SAB-AP/MECH SONACT 126 AUSTENITE Austentite has a greater electrical resistance and coefficient of expansion than ferrite. SAB-AP/MECH SONACT It is also a non-magnetic (paramagnetic) 1/5/2013 127 CEMENTITE Cementite is the name given to the carbide of It is the hard, brittle, intermetallic compound of SAB-AP/MECH SONACT iron(Fe3c). 1/5/2013 iron with 6.69% of carbon. 128 CEMENTITE The hardness and brittleness of cast iron is cementite. SAB-AP/MECH SONACT believed to be due to the presence of the 1/5/2013 It is Magnetic below 250°c 129 CEMENTITE 1/5/2013 SAB-AP/MECH SONACT 130 PEARLITE Pearlite is the eutectoid mixture of ferrite It is formed when austenite decomposes SAB-AP/MECH SONACT (87.5%) and cementite (12.5%). 1/5/2013 during cooling. It contains 0.8% of carbon 131 PEARLITE 1/5/2013 SAB-AP/MECH SONACT 132 1/5/2013 PEARLITE LAMELLAR-PEARLITE BEADED BAG SAB-AP/MECH SONACT 133 PEARLITE It consist of alternate thin layers (or lamellae) of The name derives from its lustrous apperance SAB-AP/MECH SONACT ferrite and cementite shown in fig. 1/5/2013 (similar to mother of pearl) when viewed in white light under a microscope. 134 PEARLITE The properties of pearlite is midway between and ductile. SAB-AP/MECH SONACT ferrite and cementite. It is relatively strong, hard 1/5/2013 135 LEDEBURITE Ledeburite is the eutectic mixture of austenite(γ-Iron) and In pure iron-carbon alloy, it forms at 1140 °C. Most of the engineering alloy materials belong to SAB-AP/MECH SONACT cementite (Fe3C) Containing 4.3% carbon. 1/5/2013 this range of alloy. 136 LEDEBURITE Pig iron, the most important engineering SAB-AP/MECH SONACT material, is ledeburite. 1/5/2013 137 LEDEBURITE 1/5/2013 SAB-AP/MECH SONACT 138 LEDEBURITE 1/5/2013 SAB-AP/MECH SONACT 139 MARTENSITE Martensite is the super saturated solid solution It is formed when steel is very rapidly cooled from the SAB-AP/MECH SONACT of carbon in α-Iron. 1/5/2013 austenitic state. It exhibits a characteristic acicular or needle like structure. 140 MARTENSITE It is very hard more brittle and low ductility There is an increase in specific volume during SAB-AP/MECH SONACT properties. 1/5/2013 formation of martensite from austenite. 141 MARTENSITE As a result internal stresses are set up in the cracks. SAB-AP/MECH SONACT materials leading to the formation of minute 1/5/2013 142 MARTENSITE (RED AND YELLOW MARTENSITE. GREEN: AUSTENITE) 1/5/2013 SAB-AP/MECH SONACT 143 TROOSTITE Troosite is the mixture of radial lamella of pearlite only in the degree of fitness. SAB-AP/MECH SONACT ferrite and cementite. In fact, it differs from 1/5/2013 This constituents is also known as troostite pearlite. 144 TROOSTITE It is the microstructure consisting ferrite and martensite below 450 °C SAB-AP/MECH SONACT finely divided cementite, produced on tempering 1/5/2013 145 TROOSTITE It is formed by the decomposition of austenite will yield a martensitic structure and faster than that which will produce a sorbitic structure. SAB-AP/MECH SONACT when cooled at a rate slower than that which 1/5/2013 146 TROOSTITE It has hardness intermediate between SAB-AP/MECH SONACT martensite and sorbite. 1/5/2013 147 TROOSTITE 1/5/2013 SAB-AP/MECH SONACT 148 SORBITE Sorbite is the microstructure consisting ferrite, tempering martensite above 450°C SAB-AP/MECH SONACT and finely divided cementite, produced on 1/5/2013 149 SORBITE This constituents is also known as sorbitic It is formed by the decomposition of austenite SAB-AP/MECH SONACT pearlite. 1/5/2013 when cooled at a rate slower than that which will produce a pearlitic structure 150 SORBITE Though sorbitic steel is slightly less ductile than high. SAB-AP/MECH SONACT pearlite steel, its tensile and yield strength are 1/5/2013 The sorbite steels are often known as Toughened steels. 151 SORBITE 1/5/2013 SAB-AP/MECH SONACT 152 SORBITE 1/5/2013 Note: All the pearlite, troosite and sorbite are ferritecementite mixtures having lamellar structure. However they are distinguished by their degree of SAB-AP/MECH SONACT dispersion. Pearlite has corase pearlite. 153 SORBITE And sorbite has medium pearlite SAB-AP/MECH SONACT Troosite has fine pearlite 1/5/2013 154 BAINITE Bainite is a decomposition product of austenite, Bainite is obtained by transformation of pearlite SAB-AP/MECH SONACT consisting of an aggregate of ferrite and carbide. 1/5/2013 higher temperature ( has a feathery structure) is called upper bainite. 155 BAINITE Lower bainite provides high mechanical used for components of machine and structures. SAB-AP/MECH SONACT properties and that is why it is extensively 1/5/2013 Bainite has hardness in between the hardness of pearlite and martensite. 156 BAINITE 1/5/2013 SAB-AP/MECH SONACT 157 IRON/CARBON ALLOY PHASE DIAGRAM 1/5/2013 SAB-AP/MECH SONACT 158 1/5/2013 SAB-AP/MECH SONACT 159
