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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
Reason (R): Cold working reduces the total number of dislocations per unit volume of the material
- a)Both A and R are true and R is the correct explanation of A
- b)Both A and R arc true but R is NOT the correct explanation of A
- c)A is true hut R is false
- d)A is false but R is true
Correct answer is option 'B'. Can you explain this answer?
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Assertion (A): Cold working of metals results in increase of strength ...
Explanation:
• Cold working of metals is a process of plastic deformation at temperatures below the recrystallization temperature of the metal.
• When the metal is subjected to cold working, its grain structure undergoes deformation and elongation due to the application of external forces.
• This results in an increase in the dislocation density of the metal, which in turn leads to an increase in its strength and hardness.
• The dislocations act as barriers to the movement of dislocation lines, which makes it harder for the metal to deform further under the application of external forces.
• The increase in the dislocation density also results in a decrease in the ductility of the metal, making it more brittle.
Assertion (A): Cold working of metals results in an increase in strength and hardness.
• This assertion is true as explained above.
Reason (R): Cold working reduces the total number of dislocations per unit volume of the material.
• This reason is false as the cold working process increases the total number of dislocations per unit volume of the material.
• This is because cold working creates more dislocations in the metal due to the plastic deformation and elongation of its grain structure.
Therefore, option B is the correct answer as both the assertion and reason are true, but the reason is not the correct explanation of the assertion.
• Cold working of metals is a process of plastic deformation at temperatures below the recrystallization temperature of the metal.
• When the metal is subjected to cold working, its grain structure undergoes deformation and elongation due to the application of external forces.
• This results in an increase in the dislocation density of the metal, which in turn leads to an increase in its strength and hardness.
• The dislocations act as barriers to the movement of dislocation lines, which makes it harder for the metal to deform further under the application of external forces.
• The increase in the dislocation density also results in a decrease in the ductility of the metal, making it more brittle.
Assertion (A): Cold working of metals results in an increase in strength and hardness.
• This assertion is true as explained above.
Reason (R): Cold working reduces the total number of dislocations per unit volume of the material.
• This reason is false as the cold working process increases the total number of dislocations per unit volume of the material.
• This is because cold working creates more dislocations in the metal due to the plastic deformation and elongation of its grain structure.
Therefore, option B is the correct answer as both the assertion and reason are true, but the reason is not the correct explanation of the assertion.
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Community Answer
Assertion (A): Cold working of metals results in increase of strength ...
Abhi to pichhle question me ye naser diya tha ki only hardness increased not strength
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Assertion (A): Cold working of metals results in increase of strength and hardnessReason (R): Cold working reduces the total number of dislocations per unit volume of the materiala)Both A and R are true and R is the correct explanation of Ab)Both A and R arc true but R is NOT the correct explanation of Ac)A is true hut R is falsed)A is false but R is trueCorrect answer is option 'B'. Can you explain this answer?
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Assertion (A): Cold working of metals results in increase of strength and hardnessReason (R): Cold working reduces the total number of dislocations per unit volume of the materiala)Both A and R are true and R is the correct explanation of Ab)Both A and R arc true but R is NOT the correct explanation of Ac)A is true hut R is falsed)A is false but R is trueCorrect answer is option 'B'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about Assertion (A): Cold working of metals results in increase of strength and hardnessReason (R): Cold working reduces the total number of dislocations per unit volume of the materiala)Both A and R are true and R is the correct explanation of Ab)Both A and R arc true but R is NOT the correct explanation of Ac)A is true hut R is falsed)A is false but R is trueCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion (A): Cold working of metals results in increase of strength and hardnessReason (R): Cold working reduces the total number of dislocations per unit volume of the materiala)Both A and R are true and R is the correct explanation of Ab)Both A and R arc true but R is NOT the correct explanation of Ac)A is true hut R is falsed)A is false but R is trueCorrect answer is option 'B'. Can you explain this answer?.
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