Work hardening

Definition

Work hardening, also known as strain hardening, is the process by which a metal becomes stronger and harder as it is deformed plastically. This occurs because dislocations within the material's crystal structure are created and tangled during deformation, making further deformation more difficult. As a result, the material can exhibit increased strength and resistance to further plastic deformation.

5 Must Know Facts For Your Next Test

1. Work hardening occurs primarily in ductile materials like metals when they undergo processes such as rolling, bending, or drawing.
2. The degree of work hardening depends on factors such as the amount of plastic deformation and the material's intrinsic properties.
3. As work hardening increases, a material's yield strength and ultimate tensile strength also increase, making it tougher and more resistant to further deformation.
4. Work hardened materials may become more brittle if excessively deformed, leading to potential failure under certain conditions.
5. Common examples of work-hardened metals include copper and aluminum, which are often used in applications requiring enhanced strength without significant weight increases.

Review Questions

• How does work hardening relate to plastic deformation in materials?
  • Work hardening is a direct result of plastic deformation in materials. When a ductile metal is subjected to stress beyond its elastic limit, it undergoes permanent changes in shape. During this process, dislocations are generated and interact with each other, making further deformation more challenging. As a consequence, the material becomes stronger and harder due to this entanglement of dislocations.
• What are some common processes that can lead to work hardening in metals, and how do these processes affect their properties?
  • Common processes that lead to work hardening include rolling, drawing, and bending of metals. These mechanical processes apply significant stress that causes plastic deformation. As a result of work hardening, the yield strength and ultimate tensile strength of the metal increase, allowing it to withstand greater loads without deforming further. However, it's important to note that excessive work hardening can lead to brittleness, which may cause the material to fracture under certain conditions.
• Evaluate the implications of work hardening on engineering applications, particularly regarding material selection and performance.
  • The implications of work hardening on engineering applications are significant when considering material selection and performance requirements. Engineers must account for the increased strength and hardness achieved through work hardening while also being aware of potential brittleness that may arise from excessive deformation. Choosing work-hardened materials can be advantageous in applications requiring lightweight yet strong components. However, careful design considerations must be made to ensure that these materials can endure operational stresses without failing unexpectedly due to brittleness.

Related terms

plastic deformation:

Plastic deformation refers to the permanent distortion that occurs in a material when subjected to stress beyond its elastic limit, leading to a change in shape that remains even after the stress is removed.

dislocation: A dislocation is a defect in the crystal structure of a material, which allows for the movement of atoms and contributes to plastic deformation under applied stress.

yield strength: Yield strength is the amount of stress at which a material begins to deform plastically, marking the transition from elastic behavior to permanent deformation.