191. Seamless long steel tubes are manufactured by rolling, drawing and __________.

1. 1. Extrusion & Tube piercing.

   
   
   

   2. Tube piercing.

   
   
   

   3. Steel & Tube piercing.

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   Extrusion & Tube piercing.

   Correct Option: A

   Extrusion & Tube piercing.

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192. Semi brittle materials can be extruded by

1. 1. impact extrusion

   
   
   

   2. closed cavity extrusion

   
   
   

   3. hydrostatic extrusion

   
   
   

   4. backward extrusion

   
   
   

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   Hydrostatic stresses increases the ductility of Brittle material.
   

   Correct Option: C

   Hydrostatic stresses increases the ductility of Brittle material.
   

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193. Collapsible tubes are made by

1. 1. Drawing

   
   
   

   2. Spinning

   
   
   

   3. Extrusion

   
   
   

   4. Rolling

   
   
   

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1. View Hint View Answer Discuss in Forum

   Collapsible tubes are made by extrusion process.

   Correct Option: C

   Collapsible tubes are made by extrusion process.

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194. The true stress (in MPa) versus true strain relationship for a metal is given by σ = 1020 σ^0.4 The cross-sectional area at the start of a test (when the stress and strain values are equal to zero) is 100 mm². The cross-sectional area at the time of necking (in mm²) is _____(correct to two decimal places).

1. 1. 67.032 mm²

   
   
   

   2. - 67.032 mm²

   
   
   

   3. 68.032 mm²

   
   
   

   4. 66.032 mm²

   
   
   

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1. View Hint View Answer Discuss in Forum

   σ = 1020 ∈^0.4.
   at UTS ⇒ ∈ = n = 0.4
   

   ∈ = 0.4 = ln			Ai
   			Af

   
   

   0.4 = ln			100
   			Af

   
   A_f = 67.032 mm²

   Correct Option: A

   σ = 1020 ∈^0.4.
   at UTS ⇒ ∈ = n = 0.4
   

   ∈ = 0.4 = ln			Ai
   			Af

   
   

   0.4 = ln			100
   			Af

   
   A_f = 67.032 mm²

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195. A steel wire is drawn from an initial diameter (di) of 10 mm to a final diameter (d_f) of 7.5 mm. The half cone angle (α) of the die is 5° and the coefficient of friction (μ) between the die and the wire is 0.1. The average of the initial and final yield stress [(σ_y )_avg] is 350 MPa. The equation for drawing stress σf. (in MPa) is given as:
     The drawing stress (in MPa) required to carry out this operation is (correct to two decimal places).

1. 1. 316.25 MPa

   
   
   

   2. - 316.25 MPa

   
   
   

   3. 314.25 MPa

   
   
   

   4. 315.25 MPa

   
   
   

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1. View Hint View Answer Discuss in Forum

   D_i = 10 mm, D_f = 7.5 mm
   α = 5°, µ = 0.1
   (σ_y)_avg = 350 MPa
   
   σ_f = 316.25 MPa

   Correct Option: A

   D_i = 10 mm, D_f = 7.5 mm
   α = 5°, µ = 0.1
   (σ_y)_avg = 350 MPa
   
   σ_f = 316.25 MPa

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