Definition
A physical property of a material that describes its resistance to localized deformation, particularly indentation, scratching, or abrasion. In aviation maintenance, hardness is measured using standardized tests such as Rockwell, Brinell, or Vickers, which press a specified indenter into the material under a known load and measure the resulting impression.
Plain English
How well a material resists being dented, scratched, or worn down. A harder material is more difficult to mark or wear away than a softer one.
Context Anchor
Seen in aircraft maintenance, especially when discussing metals, hardware, tools, and parts that have been heated, cooled, repaired, or tested.
Why Pilots Care
Hardness affects how a part wears, holds an edge, or resists damage. Heat treatment changes hardness, so a component with the wrong hardness may have been improperly processed and could fail in service.
Intuition Check
Hardness does not mean the same thing as overall strength. A material can be very hard on the surface and still be brittle or unsuitable for a particular aircraft part.
Example Sentence 1
After heat treatment, the technician checked the hardness of the steel fitting with a Rockwell tester to confirm it met the manufacturer's specification.
Example Sentence 2
Engine components often require higher hardness ratings to resist wear during operation.