ME-303 Materials Technology - Jun 2025 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
   aDefine engineering materials and classify them based on their properties and applications.
   How to answer

   • Definition of engineering materials
   • Broad classification: Metals, Polymers, Ceramics, Composites, Advanced/Smart materials
   • Classification based on mechanical, thermal, electrical properties
   • Industrial applications corresponding to each class
2. 7 Marks
   bExplain the concepts of ductility, hardness and creep in materials. Discuss how these properties are measured and their importance in material selection.
   How to answer

   • Definitions of ductility, hardness, and creep
   • Measurement methods: Tensile test (percentage elongation/reduction in area) for ductility
   • Hardness tests (Brinell, Vickers, Rockwell)
   • Creep testing curve (primary, secondary, tertiary stages)
   • Importance of each property in engineering design and material selection
3. 7 Marks
   aDescribe the major characteristics of alloying elements and their role in modifying the properties of base metals.
   How to answer

   • Characteristics of common alloying elements (Cr, Ni, Mo, V, Mn, etc.)
   • Mechanisms of property modification: solid solution strengthening, precipitation hardening, phase transformation control
   • Effects on mechanical properties (strength, hardness, toughness)
   • Effects on physical/chemical properties (corrosion resistance, high-temperature stability)
4. 7 Marks
   bProvide a classification of steel and discuss the properties and applications of each type.
   How to answer

   • Classification of steels based on carbon content (low, medium, high carbon steel)
   • Classification based on alloying content (low alloy, high alloy / stainless steel, tool steel)
   • Specific mechanical and physical properties of each class
   • Typical engineering applications for each category
5. 7 Marks
   aExplain the heat treatment processes for metals, including annealing, normalizing and hardening and their effects on material properties.
   How to answer

   • Objectives and general principles of heat treatment
   • Annealing: process temperature, slow furnace cooling, effects (softening, stress relief)
   • Normalizing: heating range, air cooling, fine pearlite structure formation
   • Hardening: heating above critical temperature, rapid quenching, martensitic structure
   • Comparison of effects on mechanical properties
6. 7 Marks
   bDefine cyaniding and describe its application in surface hardening of steels.
   How to answer

   • Definition of cyaniding (liquid carbonitriding process)
   • Process details: bath composition (sodium cyanide, sodium carbonate, sodium chloride) and temperature (800–900 °C)
   • Quenching mechanism and resultant case depth/composition (C and N absorption)
   • Applications, advantages, and limitations/safety concerns
7. 7 Marks
   aList the main ores of manganese and describe their properties and industrial applications.
   How to answer

   • Major ores of manganese (Pyrolusite - $\text{MnO}_2$, Psilomelane, Rhodochrosite, Braunite)
   • Physical and chemical properties of manganese ores/metal
   • Industrial applications: deoxidizing and desulfurizing agent in steelmaking
   • Applications in alloys (ferromanganese, silicomanganese), dry-cell batteries, and chemicals
8. 7 Marks
   bIdentify the main alloys of aluminium and nickel and discuss their significance in engineering applications.
   How to answer

   • Major aluminium alloys: Duralumin, Hindalium, Al-Si alloys, wrought/cast alloy series
   • Major nickel alloys: Monel, Inconel, Nichrome, Hastelloy
   • Properties: high strength-to-weight ratio for Al; high corrosion resistance and high-temperature creep resistance for Ni
   • Key engineering applications: aerospace, marine, turbine blades, chemical processing
9. 7 Marks
   aDiscuss different chemical reagents used in the metallurgical industry and their purposes.
   How to answer

   • Flotation reagents: collectors, frothers, activators, depressants
   • Hydrometallurgical/leaching reagents (acids, cyanides, alkalis)
   • Fluxes used in smelting and refining (limestone, fluorite, borax)
   • Etching reagents used in metallography (Nital, Picral, Keller's reagent) and their purposes
10. 7 Marks
    bExplain the spot test method and its application in the qualitative analysis of metals.
    How to answer

    • Principle of chemical spot testing on metal surfaces
    • Procedure: localized chemical attack, reaction with specific reagent, color development
    • Applications: rapid non-destructive identification of alloy grades, sorting scrap metals, detection of coatings/plating
    • Advantages and limitations of the spot test method
11. 7 Marks
    aDraw and annotate the stress-strain curve for polycrystalline materials, highlighting the yield point, ultimate tensile strength and fracture point.
    How to answer

    • Neat stress-strain diagram with axes labeled (Engineering stress $\sigma$ vs. Engineering strain $\epsilon$)
    • Indication of proportional limit, elastic limit, upper and lower yield points
    • Annotation of Ultimate Tensile Strength (UTS) and necking region
    • Fracture/rupture point indication
    • Brief explanation of physical significance of each designated point
12. 7 Marks
    bDescribe the main ores of chromium and their properties and uses in the industry.
    How to answer

    • Main ore of chromium: Chromite ($\text{FeCr}_2\text{O}_4$)
    • Key physical and chemical properties of chromium and chromite
    • Uses in metallurgical industry: production of stainless steel, ferrochrome, nichrome
    • Refractory applications (chromite bricks) and chemical industry uses (chrome plating, tanning)
13. 7 Marks
    aWhat is case carburizing? Explain briefly.
    How to answer

    • Definition of case carburizing (diffusion of carbon into low carbon steel surface)
    • Temperature range (austenitic region, ~900–950 °C)
    • Types: Pack carburizing, Gas carburizing, Liquid carburizing
    • Subsequent heat treatment (quenching and tempering) to achieve a hard case and tough core
14. 7 Marks
    bDescribe an few non-destructive tests for the detection of cracks in metals.
    How to answer

    • Introduction to Non-Destructive Testing (NDT)
    • Dye Penetrant Testing (DPT): principle, steps, for surface cracks
    • Magnetic Particle Testing (MPT): principle, flux leakage, for ferromagnetic surface/subsurface cracks
    • Ultrasonic Testing (UT): high-frequency sound wave reflection for internal cracks
    • Radiographic Testing (RT): X-ray/Gamma-ray detection of internal flaws
15. 7 Marks
    aWhat is Charpy impact test and what does it reveal about material toughness?
    How to answer

    • Definition and setup of the Charpy impact test (pendulum machine, standard notched specimen supported as simple beam)
    • Procedure: release of hammer, fracture of specimen, energy absorption measurement
    • Interpretation of toughness (energy absorbed in Joules)
    • Determination of ductile-to-brittle transition temperature (DBTT) via temperature variation
16. 7 Marks
    bExplain briefly the theory of tempering and the process of austempering and martempering.
    How to answer

    • Theory of tempering: relief of internal stresses, decomposition of unstable martensite into stable ferrite and carbide phases
    • Martempering (marquenching): quenching above $M_s$, holding for temperature equalization, cooling in air to form uniform martensite with reduced residual stress and distortion
    • Austempering: isothermal quenching above $M_s$ directly into the bainitic transformation zone to produce bainite
    • Comparison of mechanical properties and benefits