ME-303 Materials Technology - Dec 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDiscuss the various types of bonds found in metals and their impact on material properties.
   How to answer

   • Define primary and secondary chemical bonds (focus on metallic bonding, ionic, covalent).
   • Describe metallic bond structure (electron sea model/positive ion cores).
   • Correlate bonding nature with mechanical, thermal, and electrical properties (ductility, conductivity, melting point).
2. 7 Marks
   bExplain the terms ductility, hardness and creep, and how they influence the behaviour of materials under stress.
   How to answer

   • Define ductility (plastic deformation before fracture) and measure (% elongation).
   • Define hardness (resistance to indentation, scratching, or penetration).
   • Define creep (time-dependent permanent deformation under constant load at elevated temperatures).
   • Explain how each affects material performance under tensile, compressive, and high-temperature stress.
3. 7 Marks
   aExplain the concept of eutectoid solid solution and its significance in the steel-making process.
   How to answer

   • Define eutectoid reaction: solid phase transformation into two different solid phases ($\gamma \rightarrow \alpha + \text{Fe}_3\text{C}$ at $727^\circ\text{C}$, 0.76% C).
   • Explain the microstructural transformation from austenite to pearlite (lamellar structure of ferrite and cementite).
   • Discuss significance in tailoring hardness, tensile strength, and toughness in steel production.
4. 7 Marks
   bDescribe the cooling curves and their importance in understanding the solidification process of alloys.
   How to answer

   • Define cooling curve (temperature vs. time plot during solidification).
   • Contrast pure metal curve (isothermal plateau) with binary solid-solution alloy (thermal arrests at liquidus and solidus).
   • Sketch typical cooling curves.
   • Explain application in constructing equilibrium phase diagrams and detecting phase changes.
5. 7 Marks
   aDraw and explain the T-T-T diagram for steel and its relevance in heat treatment processes.
   How to answer

   • Draw TTT (Time-Temperature-Transformation / C-curve) diagram for eutectoid steel showing nose, start, and finish lines.
   • Label regions: Austenite, Pearlite (coarse and fine), Bainite (upper and lower), Martensite ($M_s$, $M_f$).
   • Explain critical cooling rate.
   • Discuss significance in designing heat treatment cycles (annealing, normalizing, hardening, austempering, martempering).
6. 7 Marks
   bWhat is case carburizing? Discuss its purpose and the process involved.
   How to answer

   • Define carburizing: diffusion of nascent carbon into low-carbon steel surface at austenitic temperatures ($900-950^\circ\text{C}$).
   • State purpose: achieve hard, wear-resistant outer surface (case) with tough, ductile core.
   • Describe main processes: Pack, Liquid, and Gas carburizing.
   • Outline post-carburizing heat treatment (quenching and tempering).
7. 7 Marks
   aExplain flame hardening and ion implantation as methods of surface treatment for metals.
   How to answer

   • Explain flame hardening: rapid heating using oxy-fuel torch to austenitic range followed by immediate water quenching; applied to medium carbon steels.
   • Explain ion implantation: bombardment of metal surface with high-energy ions (e.g., nitrogen) in high vacuum to modify near-surface microstructure and properties.
   • State advantages, limitations, and engineering applications of each.
8. 7 Marks
   bDescribe a few non-destructive tests for the detection of cracks in metals and their importance in quality control.
   How to answer

   • Define Non-Destructive Testing (NDT) and its role in quality assurance without impairing component serviceability.
   • Describe Dye Penetrant Testing (PT) for surface cracks.
   • Describe Magnetic Particle Testing (MT) for surface and near-surface defects in ferromagnetic materials.
   • Describe Ultrasonic Testing (UT) / Radiographic Testing (RT) for internal cracks.
   • State their role in defect detection and structural integrity evaluation.
9. 7 Marks
   aWrite short notes on volumetric and gravimetric analysis and their roles in the chemical analysis of metals.
   How to answer

   • Define volumetric analysis (titrimetric methods measuring volume of reagent of known concentration reacting with analyte).
   • Define gravimetric analysis (quantitative determination by mass of a precipitated pure compound).
   • Explain step-by-step procedures for each in identifying metallic composition.
   • Compare accuracy, speed, and typical applications in alloy chemical testing.
10. 7 Marks
    bExplain optical and spectrophotometric analysis and how they are used in the metallurgical industry?
    How to answer

    • Explain optical emission spectrometry (OES) based on excitation of atoms and emission of light at characteristic wavelengths.
    • Explain spectrophotometry based on light absorption as a function of wavelength (Beer-Lambert Law).
    • Discuss applications in rapid elemental analysis of molten metal during steelmaking and grade verification.
11. 7 Marks
    aDescribe the main ores of chromium and their significance in the metallurgical industry.
    How to answer

    • Identify principal chromium ore: Chromite ($\text{FeCr}_2\text{O}_4$).
    • Mention secondary sources/minerals if any (crocoite).
    • Discuss metallurgical significance: production of ferrochrome used in stainless steel and alloy steel manufacturing.
    • Explain its contribution to corrosion resistance, hardness, and wear resistance.
12. 7 Marks
    bList the main alloys of aluminium and nickel and explain their applications in engineering.
    How to answer

    • List key aluminium alloys: Duralumin, Hindalium, Al-Si alloys, Magnalium.
    • State engineering applications of Al alloys: aerospace structures, automotive pistons, electrical conductors.
    • List key nickel alloys: Monel, Inconel, Nichrome, Hastelloy.
    • State engineering applications of Ni alloys: turbine blades, heating elements, chemical processing vessels.
13. 7 Marks
    aWhat do you mean by crystal Imperfection? Explain.
    How to answer

    • Define crystal imperfection / defect: deviation from ideal, periodic arrangement of atoms in a crystal lattice.
    • Classify defects by dimensionality: 0D (point - vacancy, interstitial, Frenkel, Schottky), 1D (line - edge and screw dislocations), 2D (planar - grain boundaries, stacking faults), 3D (volume - voids, inclusions).
    • Briefly explain their effect on plastic deformation and mechanical properties.
14. 7 Marks
    bDraw an Iron-Carbon phase diagram? Explain.
    How to answer

    • Draw neat, labeled $Fe\text{-}Fe_3C$ phase diagram up to 6.67% C and $1600^\circ\text{C}$.
    • Label all phases: $\alpha$-ferrite, austenite ($\gamma$), $\delta$-ferrite, cementite ($Fe_3C$), liquid.
    • Identify and write the three invariant reactions with temperatures and compositions: Peritectic ($1495^\circ\text{C}$), Eutectic ($1147^\circ\text{C}$), and Eutectoid ($727^\circ\text{C}$).
    • Briefly explain significance in classification of steels and cast irons.
15. 7 Marks
    aWhat is a charpy impact test, and how does it assess the toughness of a material?
    How to answer

    • Define Charpy impact test: a standardized dynamic test using a swinging pendulum to fracture a V-notched specimen supported at both ends as a simple beam.
    • Explain the measurement principle: absorbed impact energy determined from the difference between initial potential energy and post-fracture rebound height.
    • Sketch specimen and test configuration.
    • Explain how absorbed energy evaluates notch sensitivity and ductile-to-brittle transition temperature (DBTT).
16. 7 Marks
    bExplain the significance of ductility, malleability, toughness and brittleness in materials engineering.
    How to answer

    • Define each property: ductility (drawn into wires under tension), malleability (flattened into sheets under compression), toughness (energy absorption before fracture), brittleness (fracture with little or no plastic deformation).
    • Explain their engineering importance in manufacturing processes (wire drawing, rolling, forging).
    • Discuss their role in structural design and failure prevention under static and impact loads.