Which term describes a material's capacity to resist plastic deformation, penetration, indentation, and scratching?

Which term describes a material's capacity to resist plastic deformation, penetration, indentation, and scratching?

• A. Elasticity
• B. Brittleness
• C. Hardness
• D. Degradation

Answer: (C)

Hardness describes a material's resistance to local plastic deformation, including penetration, indentation, and scratching. When a force is applied at a small scale, a harder material resists leaving a permanent impression more than a softer one. Elasticity, in contrast, is about reversible deformation when the load is removed; a material can recover its shape. Brittleness refers to a tendency to fracture with little plastic deformation, not to surface resistance. Degradation means loss of properties over time due to environmental or chemical effects, not resistance to indentation. Hardness is measured with tests like Rockwell, Vickers, or Brinell, linking the surface resistance to wear and scratching performance in service. However, hardness isn’t the same as toughness or tensile strength; a material can be very hard yet brittle.

Hardness describes a material's resistance to local plastic deformation, including penetration, indentation, and scratching. When a force is applied at a small scale, a harder material resists leaving a permanent impression more than a softer one. Elasticity, in contrast, is about reversible deformation when the load is removed; a material can recover its shape. Brittleness refers to a tendency to fracture with little plastic deformation, not to surface resistance. Degradation means loss of properties over time due to environmental or chemical effects, not resistance to indentation. Hardness is measured with tests like Rockwell, Vickers, or Brinell, linking the surface resistance to wear and scratching performance in service. However, hardness isn’t the same as toughness or tensile strength; a material can be very hard yet brittle.