Cold Working Hot Working Q A For Students

7/22/2011

IES 2011

Metal Forming By  S K Mondal Compiled By: S K Mondal                    Made Easy

GATE‐2003  Cold working of steel is defined as working (a) At its recrystallisation temperature (b) Above its recrystallisation temperature (c) Below its recrystallisation temperature (d) At two thirds of the melting temperature of the metal Ans. (c)

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IES – 2006 Which one of the following is the process to refine the grains of metal after it has been distorted by hammering or cold working? (a) Annealing (b) Softening (c) ( ) Re‐crystallizing R t lli i (d) Normalizing N li i Ans. (c)

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Assertion (A): Lead, Zinc and Tin are always hot worked. Reason (R) : If they are worked in cold state they cannot retain their mechanical properties. (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true Ans. (c) Compiled By: S K Mondal                    Made Easy

GATE‐2002 Hot rolling of mild steel is carried out (a) At recrystallisation temperature (b) Between 100°C to 150°C (c) Below recrystallisation temperature (d) Above recrystallisation temperature Ans. (d)

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IES – 2004 Consider the following statements: In comparison to hot working, in cold working, 1. Higher forces are required 2. No heating is required 3. Less ductility is required 4. Better surface finish is obtained Which of the statements given above are correct? (a) 1, 2 and 3 (b) 1, 2 and 4 (c) 1 and 3 (d) 2, 3 and 4 Ans. (b) Compiled By: S K Mondal                    Made Easy

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IES – 2009

IES – 2008

Consider the following characteristics: 1. Porosity in the metal is largely eliminated. 2. Strength is decreased. 3. Close tolerances cannot be maintained. Which of the above characteristics of hot working is/are correct? (a) 1 only (b) 3 only (c) 2 and 3 (d) 1 and 3 Ans. (d)

Consider the following statements: 1. Metal forming decreases harmful effects of impurities and improves mechanical strength. 2. Metal working process is a plastic deformation process. 3. Very intricate shapes can be produced by forging process as compared to casting process. Which of the statements given above are correct? (a) 1, 2 and 3 (b) 1 and 2 only (c) 2 and 3 only (d) 1 and 3 only Ans. (b) Compiled By: S K Mondal                    Made Easy

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IES – 2008

IES – 2004

Cold forging results in improved quality due to which of the following? 1. Better mechanical properties of the process. 2. Unbroken grain flow. 3. Smoother finishes. 4. High pressure. Select the correct answer using the code given below: (a) 1, 2 and 3 (b) 1, 2 and 4 (c) 2, 3 and 4 (d) 1, 3 and 4 Ans. (a)

Assertion (A): Cold working of metals results in increase of strength and hardness Reason (R): Cold working reduces the total number of dislocations per unit volume of the material ( ) Both (a) B th A and d R are individually i di id ll true t and d R is i the th correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true Ans. (c) Compiled By: S K Mondal                    Made Easy

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IES – 2003 Cold working produces the following effects: 1. Stresses are set up in the metal 2. Grain structure gets distorted 3. Strength and hardness of the metal are decreased 4. Surface finish is reduced Which of these statements are correct? (a) 1and 2 (b) 1, 2 and 3 (c) 3 and 4 (d) 1 and 4 Ans. (a) Compiled By: S K Mondal                    Made Easy

IES – 2000 Assertion (A): To obtain large deformations by cold working intermediate annealing is not required. Reason (R): Cold working is performed below the recrystallisation temperature of the work material. ( ) Both (a) B th A and d R are individually i di id ll true t and d R is i the th correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true Ans. (d) Compiled By: S K Mondal                    Made Easy

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IES – 1997 In metals subjected to cold working, strain  hardening effect is due to (a) Slip mechanism (b) Twining mechanism (c) Dislocation mechanism (d) Fracture mechanism Ans. (c)

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IES – 2006 Assertion (A): In case of hot working of metals, the temperature at which the process is finally stopped should not be above the recrystallisation temperature. Reason (R): If the process is stopped above the recrystallisation temperature, grain growth will take place again and spoil the attained structure. structure (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true Ans. (d) Compiled By: S K Mondal                    Made Easy

IES – 1996 Consider the following statements: When a metal or alloy is cold worked 1. It is worked below room temperature. 2. It is worked below recrystallisation temperature. 3. 3 Its hardness and strength increase. Its hardness and strength increase 4. Its hardness increases but strength does not  increase. Of these correct statements are (a) 1 and 4  (b) 1 and 3  (c) 2 and 3  (d) 2 and 4 Ans. (c) Compiled By: S K Mondal                    Made Easy

IES – 1992 Specify the sequence correctly (a) Grain growth, recrystallisation, stress relief (b) Stress relief, grain growth, recrystallisation (c) Stress relief, recrystallisation, grain growth (d) Grain growth, stress relief, recrystallisation Ans. ( c)

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IAS – 1996

IAS – 2004

For mild steel, the hot forging temperature range is (a) 4000C to 6000C (b) 7000C to 9000C (c) 10000C to 12000C (d) 13000Cto 15000C Ans. (c)

Assertion (A): Hot working does not produce strain  hardening. Reason (R): Hot working is done above the re‐ crystallization temperature. ( ) Both A and R are individually true and R is the  (a) B th A  d R   i di id ll  t   d R i  th   correct explanation of A (b) Both A and R are individually true but R is not the  correct explanation of A  (c) A is true but R is false (d) A is false but R is true Ans. (a) Compiled By: S K Mondal                    Made Easy

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IAS‐2002 Assertion (A): There is good grain refinement in hot working. Reason (R): In hot working physical properties are generally improved. (a) and ( ) Both B th A and d R are individually i di id ll true t d R is i the th correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true Ans. (b) Compiled By: S K Mondal                    Made Easy

IES Made Easy

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