1. Write the Ms temperature equation. Calculate the Ms temperature for a carbon steel with 0.2C, 0.4 Si, 0.7Mn and for an alloy with 0.2C, 0.4Si, 0.7Mn, 1,0%Cr and 0.3%Mo. 2. What do you mean by white layer in nit riding process ? 3. What is the difference between harden ability and hardness. 4. What is need for sub zero treatment? 5. What are the application of carbonitriding? 6. Why we are not heat treating ferritic stainless steels. 7. Why the carbon content is restricted to 6.67% in the Iron-Carbon diagram. 8. Why we are not heating the hyper eutectoid steels above the upper critical temperature for annealing. 9. Draw the microstructure of a 0.4% carbon steel (a) Annealed (b) Normalized and (c) Hardened condition. 10. Why we are not hardening mild steel. PART - B (5 X 16 = 80 Marks) 11. (a) Discuss in detail the mechanism of pearlitic and bainitic transformation. (8) (b) How to develop the TTT diagram. Draw the TTT diagram for an eutectoid steel and explain the various factors affecting it. (8)
12.(a) Discuss in detail the heat treatment temperature, holding time, microstructural changes for annealing, normalising, hardening and tempering for a 0.2% carbon steel, 0.8% carbon steel, 1.2% carbon steel. (16) ( OR ) (b) Discuss briefly Jominy End quench test and hardenability testing based on ASTM Number and chemical composition. (16) 13. (a) (i) Give a detailed account of gas carburizing. (8) (ii) Explain in detail different methods of Nitriding and give the advantages advantages and limitations. limit ations. (8) ( OR ) (b) (i) Discuss in detail silionising, chronising and boronising processes. (8) (ii) Explain flame hardening and induction hardening with neat sketches. (8)
14. (a) (i) Give a detailed account of various quenching media's used and their characteristics (8) (ii) Give a detailed account of various types of furnace atmospheres. (8) ( OR ) (b) (i) List the various types of heat treatment furnaces and explain the working of fluidised bed heat treatment furnace. (8) (ii) Discuss in detail about temperature control in heat treatment furnaces. (8) 15. (a)(i) Explain in detail heat treatment of white cast iron and grey cast iron. (8) (ii)Give the typical heat treatment for a high speed tool steep and explain the different steps. (8) ( OR ) (b)(i) Discuss in detail precipitation hardening of an aluminium copper alloy.(8) (ii) List the various defects normally observed in heat treated parts and discuss the causes and remedies for any four such defects. (8)
Answer ALL questions. PART A — (10 ´ 2 = 20 marks) 1. Define Fracture Toughness. 2. What is Arrhenius equation? What are its uses? 3. Give two examples for precipitation hardenable steels. 4. Show the relationship between critical stress intensity factor KIC and thickness of the material. 5. Why heterogeneous nucleation occurs more readily than homogeneous nucleation? 6. What is the effect of applied stress on martensite formation? 7. What are the essential conditions for precipitation hardening? 8. What is low cycle fatigue? Give two examples where this is significant. 9. State the factors that influence creep rate in metals. 10. What are the different types of martensites in steels? PART B — (5 ´ 16 = 80 marks) 11. (i) What are the steps in precipitation hardening? (6) (ii) Explain the mechanism and stages in the strengthening of alloys by precipitation hardening with a suitable example. (6) (iii) Compare dispersion strengthening and precipitation strengthening. Give one example for
each. (4) (a) (i) Derive an expression for the critical free energy change of a spherical particle homogeneously nucleating from the melt. (10) (ii) Discuss how the activation energy for a reaction can be determined graphically. (6) Or (b) (i) Discuss the mechanism of pearlite formation in steels. (8) (ii) Discuss uphill diffusion with suitable examples. (8) (a) (i) What are the characteristics of martensitic transformation? Discuss with reference to steels. (10) (ii) Discuss briefly martensitic transformation in non – ferrous alloys. (6) Or (b) (i) What is shape memory effect in alloys? Give two examples and applications for shape memory alloys. (10) (ii) What is thermoelastic martensite? (6) 12. (a) (i) Discuss strengthening of metal by grain size control. (8) (ii) What are the factors that can control the grain size of steels? (8) Or (b) What are the different modes of fracture? Explain stress intensity factor. Discuss the factors that influence fracture toughness. (16) 13. (a) State Griffith's theory of brittle fracture and derive the Griffith's equation. Explain Orowan's modification suggested to Griffith's equation. (16) Or (b) (i) Explain low cycle fatigue and high cycle fatigue with the use of Coffin – Manson law and Basquin's law. (10) (ii) Discuss the mechanism of creep failure in metals. (6)
1. (a) Name and discuss atleast four important metallic properties? (b) What causes metals to show alloying behavior? [8+8] 2. (a) Differentiate between a single crystal and polycrystalline material? (b) Explain why fine grained materials have superior properties than coarse grained materials? (c) Explain the purpose of etching in metallographic examination? [6+6+4] 3. (a) Write short notes on: i. Austenite ii. Alpha ferrite iii. Delta ferrite iv. Cementite (b) Write the allotropy nature of iron with temperature and also explain the effect of pressure on allotropy of iron? [8+8] 4. (a) Write in detail about hot working tool steels and cold working tool steels? (b) Write in detail about nickel steels? [8+8]
5. (a) Carburized components are subjected to subsequent hardening heat treatment. However, nitrided articles will not be heat treated subsequently. Explain why? (b) What is chemical heat treatment? Explain how it is done? What are t he properties of cyamided case? [6+10] 6. Discuss the following alloys: (a) Cupronickels (b) Beryllium Bronzes. [8+8] 7. (a) Briefly explain few mechanical properties of ceramic materials. Also describe how the strength of the glass can be increased. (b) Discuss briefly glass forming. [10+6] 8. (a) What is the purpose of reinforcements? Describe different types of reinforcements in composites. (b) Suggest an appropriate matrix to be used for the following fiber t ypes with proper instification: i. SiC, ii. Polyethylene iii. E-glass. [10+6]
1. (a) The distance between (111) plane in FCC crystal is 2A0. Find out lattice parameter and atomic diameter? (b) Describe briefly miller bravais indices? (c) Distinguish between space lattice and crystal structure? (d) Give the relation between lattice parameter ‗a‘ and atomic radius ‗r‘ for simple cubic, BCC, FCC and HCP with examples? [4+4+4+4] 2. (a) What are intermediate phases? Discuss various types of intermediate phases? (b) What is the importance of ratio of radius of interstitial to solvent atom in interstitial compounds? [8+8] 3. (a) Explain the procedure of preparation of steel samples for metallographic examination? (b) Under Microscope grain boundaries appear black. Why? (c) Ferrite and Cementite both etch white but their mixture pearlite normally appears as black and white plates. Why? [8+4+4] 4. (a) Give the typical composition of white cast iron? (b) Explain the malleabilizing treatment given to white cast Iron with a neat sketch? (c) Explain the composition, microstructure and properties of gray cast Iron?[2+7+7] 5. (a) Distinguish between an alloy and a solid solution. (b) Compare and contrast annealing and normalizing treatments. [4+12] 6. (a) Distinguish between manganese bronze and aluminium bronze. Mention their properties and uses.
(b) Discuss briefly: i. 70:30 Brass and ii. Muntz metal. [8+8] 7. (a) In a heterogeneous multiphase refractory, what are the microstructural features present? Mention their applications. (b) Why chemically synthesized magnesium-aluminate spinel is used exclusively as refractory in molten salt electrolysis cell for producing magnesium? [10+6] 8. (a) What are the characteristics of Al-MMC-continuous filament? Mention their applications. (b) Describe briefly any two important methods of component manufacture of composites. [6+10]
1. Write a short note on (a) Nucleation and growth (b) Micro segregation and macro segregation (c) Homogeneous and Heterogeneous nucleation (d) Directional solidification. [4+4+4+4] 2. (a) Why is an octahedral void called Octahedral? (b) Draw a unit cell of FCC and also show atleast one octahedral void in it. How many such voids are present in it? (c) Draw a unit cell of BCC and show atleast one octahedral void in it. How many such voids are present in it? (d) Draw a unit cell of HCP. Show one of the octahedral holes in it. How many octahedral holes are present in it? [4+4+4+4] 3. Duralumin alloy rivets used in aircraft construction are kept at -400C after solution treatment. Whenever required they are taken out and riveted on the spot. Explain the reason for keeping them at -400C and also explain how rivets operation at room temperature strengthen the rivets? [16] 4. (a) Give the classification of stainless steels? (b) Explain each type of steel with chemical composition, microstructure, properties and applications? [4+12] 5. (a) What is Martensite? Distinguish between Lath Martensite and Accicular martensite. (b) Discuss briefly Nitriding of steels. [8+8] 6. Discuss the following alloys: (a) Cupronickels (b) Beryllium Bronzes. [8+8] 7. (a) Compare the properties of crystalline ceramics and glass ceramics. (b) Why annealing and tempering operations are performed on glass? Describe. 8. (a) What is the role of matrix in a composite material? Discuss various types matrix materials.
(b) Indicate any one important metal matrix composite and mention its characteristics, properties and applications.
1. (a) Define grain and grain boundary? How does the presence of grain boundary affect the physical and mechanical properties of metals? (b) What is the effect of heating rate and cooling rate of steel on grain growth and properties of steel?( Consider heating to Austenite zone and cooling from the same zone)? [8+8] 2. (a) What are intermediate phases? Discuss various types of intermediate phases? (b) What is the importance of ratio of radius of interstitial to solvent atom in interstitial compounds? [8+8] 3. (a) Discuss the effect of alloying elements in Fe-Fe3C diagram? (b) Discuss the effect of carbon on i. Mechanical properties ii. Grain size. [8+8] 4. (a) Give the heat treatment and applications for the following steels i. Austenitic stainless steels ii. Martensitic stainless steels iii. Ferritic stainless steels iv. Precipitation hardening stainless steels. (b) Explain each type of steel with chemical composition, microstructure, properties and applications? [16] 5. (a) What is the difference between Iron-Cementite and Iron-graphite phase diagram? (b) Draw T-T-T diagram for a eutectoid steel and explain the effect of cooling rate on the transformation products and hardness obtained. [6+10] 6. (a) Differentiate between oxygen free high conductivity copper and electrolytic tough pitch copper. Indicate their relative conductivities. (b) For any three important brasses, give composition, treatment, structure, properties and applications. [4+12] 7. Discuss the effect of the following factors on mechanical behaviour of ceramic materials: (a) grain size and shape (b) Purity and (c) Porosity [8+4+4] 8. (a) What are laminates? Indicate their characteristics. (b) Compare and contrast carbon matrices with glass matrices.
1. (a) Define crystallization of metal? How is that commercial alloy invariably solidify with heterogeneous nucleation?
(b) What factor favours the formation of fine grained material? How is a large single crystal being produced? [8+8] 2. (a) Discuss in detail the necessity of alloying with few examples. (b) Explain how are alloys actually made in industry? [8+8] 3. (a) Define cast irons ? Explain the cooling history of 4.3% C in Fe-Fe3C system by drawing cooling curve? (b) Calculate proportionate of different phases for 2.8%C in Fe-Fe3C diagram at 12000C, 11730C, and 6000C. Also draw the microstructures at room temperature? [6+10] 4. (a) Why stainless steels are stainless? (b) Is it possible to harden 18%Cr-8%Ni steels by heat treatment? (c) Why Austenitic stainless steels prone to welddecay? How can you avoid weld decay? [2+7+7] 5. (a) Distinguish between hardness and hardenability. (b) Critically discuss Pack carburizing of steels. [5+11] 6. (a) What are light metals? Explain the important characteristics of aluminium and its alloys. (b) Describe alloy and temper designation of Al and its alloys. [8+8] 7. (a) Calculate the density of FeO which has an NaCl-type structure. (assume stoichiometry). Radius of Iron is 0.74A0 & oxygen is 1.40 A0. (b) Discuss briefly the structure, properties and uses of Al2O3. [6+10] 8. (a) Explain how to improve damping ability of a composite. (b) Compare and contrast whisker and particulate reinforced composites. 1. (a) What is the importance of grain size in steel? How do you determine grain size of the given steel? (b) Explain why grains are stronger than grain boundaries at high temperature and grain boundaries are stronger than grains at room temperatures? [8+8] 2. (a) Distinguish between commercially pure metal and an alloy? (b) What is a master alloy? What are its chief characteristics? (c) Justify the statement ― Alloy is a material which is expected of a metal, but it is not a pure metallic element‖. [6+6+4] 3. (a) Name possible types of Cementite in Fe-Fe3C diagram? Explain why proeutectiod product forms at grain boundaries of austenite ? (b) Differentiate between i. Proeutectiod ferrite and eutectoid ferrite ii. Hypoeutectic and Hyper eutectic white cast iron. [8+8] 4. What are four basic types of cast Irons? Explain them with respect to properties, microstructure with a diagram and applications? [16] 5. (a) What is an alloy? Give two examples. (b) Discuss in detail the effect of alloying elements in steels. [4+12]
6. (a) Alpha brasses are cold worked while Alpha-Beta brasses are hot worked. Explain. (b) Extensive coring occurs in cast bronzes compared to cast brasses. Give reasons. (c) What is dezincification? What are its effects? How is it prevented? [7+4+5] 7. (a) In a heterogeneous multiphase refractory, what are the microstructural features present? Mention their applications. (b) Why chemically synthesized magnesium-aluminate spinel is used exclusively as refractory in molten salt electrolysis cell for producing magnesium? [10+6] 8. (a) What is aspect ratio? Why is it so important? (b) Discuss briefly about whisker reinforced composites? PART A — (10 ´ 2 = 20 marks) 1. Define Strain Hardening. 2. Compare edge and screw dislocation. 3. Sketch a tensile test specimen showing all dimensions in mm. 4. What type of grips are provided in a torsion testing machine to fix the specimen? 5. List out the different types of Hardness testing machines. 6. What property of metal does the impact test measure? Give its significance. 7. What is true stress? How to determine the same? 8. Define Endurance limit. 9. Sketch and mark the various stages in creep. 10. What are the four basic variables involved in creep tests? PART B — (5 ´ 16 = 80 marks) 11. Explain different types of fatigue stress cycle, stresses and ratios. 12. (a) Explain strengthening mechanism due to dislocations with neat sketches. Or (b) List out the types of deformations in metals. With a neat sketch explain any one type of plastic deformation. 13. (a) State the working principle of the machine used for tension test. What care should be taken while performing a test on UTM? Or (b) State the importance of torque – twist curve and explain how to determine modulus of rigidity from torque – twist curve. 14. (a) Explain the working principles of machines used to conduct Charpy and Izod impact test. How specimens are put – up in both the tests? Why? Or (b) Discuss the factors considered for selection of hardness testing machine. What care must be taken while selecting specimens for hardness test.
15. (a) Define fracture. Explain the types of fracture. Which type of fracture is preferable? Why? Or (b) Discuss the following : (i) Notch effects on fracture (ii) Stages in the formation of ductile fracture. ——————
1.a) Explain the factors influencing critical cooling rate. Explain hardenability of steel. b) Describe two different methods of obtaining spheroidized cementite structure? 2.a) Draw I-T diagram of 1080 steel and show a cooling curve that will result in a structure of (i)50% pearlite + 50% Mrtensite (ii)uniform pearlitic structure of Rc 4 0 (iii)100% Martensite (iv)100% coarse pearlite(v)100% fine pearlite. b) Explain the residual stresses setup during handening. What is the purpose of deep freezing. 3.a) Explain temper brittleness in steels and suggest remedy? b) What are the advantages and limitations of austempering? c) Explain heat treatment to be given after carburising. 4.a) Describe precipitation hardening treatment. Differentiate between coherent and incoherent precipitates. b) What is the purpose of addition of alloying elements to the steels? c) What is the effect of alloying elements upon Iron-Iron carbide diagram? 5. Write short notes on any THREE of the following: a)Precipitation hardening stainless steels (b) HSLA steels ©Maraging steel c)Heat resisting steels (d) High speed tool steel. 6. Explain Malleablising treatment. Explain structure, properties and applications of Ni-hard and S.G.Iron. 7. Briefly write on any THREE of the following : a) Muntz metal (b) Al-Li alloys (c) Titanium alloys d) Nickel based super alloys (e) Babbits 8.a) Explain heat treatment, properties and applications of Ti-6Al – 4V alloy? b) Explain the control of heat treatment atmospheres. What are the difficulties involved in vacuum heat treatment
