Explanation:

Cold working, also known as cold forming or cold rolling, is a process used to strengthen metals by deforming them at low temperatures. The strain hardening effect is a result of this process. The answer to the given question is option A, i.e. slip mechanism. The following points explain the role of slip mechanism in strain hardening:

Slip Mechanism:

Slip is the movement of dislocations in a crystal lattice under an applied stress. Dislocations are the defects in the crystal structure of metals that cause plastic deformation. When a metal is subjected to cold working, the dislocations move and multiply, causing the metal to become harder and stronger. This process is known as strain hardening.

Process of Strain Hardening:

The process of strain hardening involves the following steps:

1. Deformation: The metal is deformed by rolling, bending, or stretching at low temperatures.

2. Dislocation Movement: The applied stress causes the dislocations to move and multiply.

3. Obstacle Interaction: The movement of dislocations is hindered by obstacles such as other dislocations, impurities, and grain boundaries.

4. Strain Hardening: The obstacles increase the resistance to dislocation movement, making the metal harder and stronger.

Advantages of Strain Hardening:

The following are the advantages of strain hardening:

1. Increased Strength: Strain hardening increases the strength of metals without changing their chemical composition.

2. Improved Ductility: Strain hardening improves the ductility of metals, making them less brittle and more resistant to fracture.

3. Cost-Effective: Strain hardening is a cost-effective way of strengthening metals without the need for additional materials or processes.

Conclusion:

In conclusion, strain hardening is a process that strengthens metals by deforming them at low temperatures. The strain hardening effect is due to the movement of dislocations in the crystal lattice of metals, which is known as the slip mechanism. This process increases the strength and ductility of metals, making them more resistant to fracture.

Strain hardening is a process where material is subjected to undergo plastic deformation and gains strength.
how the strength increase is: when a slip is being propagated post yield point it involves permanant deformation as the atoms move away from their natural position the other atoms will exhibit a pull on the moving dislocation there by arresting the slip. arresting the slip means it requires more force than Usual to cause the motion again i.e. increase to with stand load (aka strength increase) inturn makes the metal less ductile and more brittle.

hence due to the behaviour of dislocations strain hardening happens. don't confuse it with slip ( slip is an effect caused by dislocation it is not a mechanism by itself)