Plain English Meaning
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.
Full 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.
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.