Materials Science and Manufacturing Engineering Miscellaneous

Materials Science and Manufacturing Engineering Miscellaneous

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Materials Science and Manufacturing Engineering

Materials Science and Manufacturing Engineering Miscellaneous
  1. Spot welding of two 1 mm thick sheets of steel (density = 8000 kg/m³) is carried out successfully by passing a certain amount of current for 0.1 second through the electrodes. The resultant weld nugget formed is 5 mm in diameter and 1.5 mm thick. If the latent heat of fusion of steel is 1400 kJ/kg and the effective resistance in the welding operation is 200 μ-ohms, the current passing through the electrodes is approximately








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    ρ = 8000 kJ/m³
    t = 0.1 sec dn = 5 mm
    hn = 1.5 mm
    LH = 1400 kJ/kg R = 200 µΩ
    I =?
    mass = 8000 × 10-9 × (π/4) 5² × 1.5
    = 2.356 × 10-4kg.
    Heat = 1400 × 8000 × 2.356 × 10-4
    = 329.8 Joules
    Heat = I² × 200 × 10-6 × 0.1
    I = 4060 Amp.

    Correct Option: C

    ρ = 8000 kJ/m³
    t = 0.1 sec dn = 5 mm
    hn = 1.5 mm
    LH = 1400 kJ/kg R = 200 µΩ
    I =?
    mass = 8000 × 10-9 × (π/4) 5² × 1.5
    = 2.356 × 10-4kg.
    Heat = 1400 × 8000 × 2.356 × 10-4
    = 329.8 Joules
    Heat = I² × 200 × 10-6 × 0.1
    I = 4060 Amp.

  1. Filler material is.... A... in resistance welding and the heat generated in the process is directly proportional to.... B....










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    Not used & square of the current H = I² Rt.

    Correct Option: E

    Not used & square of the current H = I² Rt.

  1. Autogeneous gas tungsten arc welding of a steel plate is carried out with welding current of 500 A. Voltage of 20 V and weld speed of 20 mm/ min. Consider the heat transfer efficiency from the arc to the weld pool as 90%. The heat input per unit length (in kJ/mm) is








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    Current = 500 A
    Voltage = 20 V
    V = 20 mm/min
    ηHT = 0.9

    Heat Input/length = ηHT
    V × I
    		 =
    0.9 × 20 × 500
    N20/60

    = 27 kJ/mm

    Correct Option: A

    Current = 500 A
    Voltage = 20 V
    V = 20 mm/min
    ηHT = 0.9

    Heat Input/length = ηHT
    V × I
    		 =
    0.9 × 20 × 500
    N20/60

    = 27 kJ/mm

  1. Group-I
    P. Arc welding
    Q. Friction welding
    R. Solid state Welding
    S. Laser welding
    Group-II
    1. Diffusion
    2. Polarity
    3. Focusing
    4. Kinetic energy








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    Arc welding - Polarity
    Friction welding - Kinetic energy
    Solid state welding - Diffusion
    Laser welding - Focusing

    Correct Option: D

    Arc welding - Polarity
    Friction welding - Kinetic energy
    Solid state welding - Diffusion
    Laser welding - Focusing

  1. Circular blanks of 35 mm dia are punched from a steel sheet of 2 mm thickness. If the clearance per side between the punch and die is to be kept as 40 microns. The sizes of punch and die should respectively be








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    Dia of Die = 35 mm
    Dia of Punch = 35 – 2 × 0.04 = 34.92mm

    Correct Option: B

    Dia of Die = 35 mm
    Dia of Punch = 35 – 2 × 0.04 = 34.92mm